From 11cc05bd073c7e88444fb66a89e1c70e72222fe1 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Fri, 25 Sep 2026 21:01:03 -0700 Subject: [PATCH 1/7] docs(hardware): add the AkidaTag datasheet, technical specifications and schematic pages Three portable Markdown pages under docs/hardware describe the revision 2 board for the launch documentation site: the datasheet is the engineering reference (block diagram, functional description, pin assignment, connectors, electrical characteristics, power modes, firmware interfaces, mechanical, revision history), the technical specifications page is the buyer-facing sheet, and the schematic page carries the power tree, every bus as a table and the AKD1500 strap configuration. Every value traces to the revision 2 design files, the firmware on main, the public AKD1500 product brief or the Nordic nRF5340 page; values with no source are left as visible TBD markers rather than estimated. The three figures are original SVG drawn in the BrainChip palette from the netlist, bill of materials and board outline; no design file is copied. The pin table records seven places where the firmware's board definition still describes the earlier board revision (camera SPI pins and supply enable, push button, LED mapping, INA190 gain default, flash JEDEC ID, and an unused reset node on the blue LED pin). --- docs/hardware/datasheet.md | 544 ++++++++++++++++++ .../images/akidatag-block-diagram.svg | 155 +++++ .../images/akidatag-board-outline.svg | 68 +++ docs/hardware/images/akidatag-power-tree.svg | 95 +++ docs/hardware/schematic.md | 236 ++++++++ docs/hardware/technical-specifications.md | 152 +++++ 6 files changed, 1250 insertions(+) create mode 100644 docs/hardware/datasheet.md create mode 100644 docs/hardware/images/akidatag-block-diagram.svg create mode 100644 docs/hardware/images/akidatag-board-outline.svg create mode 100644 docs/hardware/images/akidatag-power-tree.svg create mode 100644 docs/hardware/schematic.md create mode 100644 docs/hardware/technical-specifications.md diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md new file mode 100644 index 0000000..aeeee53 --- /dev/null +++ b/docs/hardware/datasheet.md @@ -0,0 +1,544 @@ +# AkidaTag datasheet + +AkidaTag is a battery-powered, Bluetooth Low Energy edge-AI development device that pairs a +Nordic nRF5340 wireless system-on-chip with the BrainChip AKD1500 Akida neuromorphic +co-processor. It carries two MEMS microphones, a six-axis inertial sensor, a camera +expansion header, on-board model storage, a single-cell Li-ion charger and fuel gauge, and +a USB-C port for charging and firmware update. The companion BrainChip Connect mobile +application connects to it over Bluetooth to load models and run the demonstrations. + +This page is the engineering reference for the board. The buyer-facing summary is the +[technical specifications](technical-specifications.md) page, and the circuit-level view +is the [schematic](schematic.md) page. + +| Document status | | +|---|---| +| Hardware described | AkidaTag hardware revision 2, design NRF-AKD1500-002 | +| Firmware referenced | AkidaTag firmware 1.2.0+0, the `main` branch of this repository | +| Status | Draft for review. Every entry marked `TBD:` is a value that no design file, firmware source or datasheet in reach provides, and is awaiting confirmation. Nothing on this page is estimated. | + +--- + +## 1. Features + +- **Host processor:** Nordic nRF5340, dual Arm Cortex-M33; 128 MHz application core with + 1 MB flash and 512 KB RAM, 64 MHz network core running the Bluetooth Low Energy + controller. +- **AI co-processor:** BrainChip AKD1500 Akida neuromorphic processor, 22 nm FD-SOI, + 7 mm x 7 mm BGA, driven over a dedicated high-speed SPI host interface at up to 32 MHz, + with a 25 MHz crystal and an internal PLL for a core clock of up to 400 MHz. +- **On-device learning:** the AKD1500 learns new classes on the device itself; the + firmware exposes this over Bluetooth for keyword spotting. +- **Model storage:** 16 MB SPI NOR flash attached to the AKD1500's own SPI master port, + written by the host through the AKD1500's slave-to-master feed-through. +- **Firmware storage:** 16 MB SPI NOR flash on the nRF5340 holding the firmware update + slot and a LittleFS file system. +- **Audio:** two digital PDM MEMS microphones on a shared PDM bus, powered through a + switched rail. +- **Motion:** STMicroelectronics ISM330DHCX six-axis accelerometer and gyroscope on I2C, + with its INT1 line to the host. +- **Camera expansion:** 10-pin 1.27 mm header with a level-shifted SPI bus and a switched + 3.3 V supply, used by the firmware with an ArduCam Mega SPI camera. +- **Wireless:** Bluetooth Low Energy through an on-board 2.4 GHz chip antenna, with an + unpopulated U.FL footprint for a test connector. +- **Power:** single-cell Li-ion battery with a BQ25185 linear charger and power path, a + BQ27427 fuel gauge, a 1.8 V buck-boost converter, a 0.8 V buck converter for the + AKD1500 core, a 3.3 V LDO for the camera header, five load switches under firmware + control, and two INA190 current-sense amplifiers feeding the nRF5340 ADC so the + firmware can measure the 1.8 V and 0.8 V rails. +- **USB-C:** 5 V input for charging and a CP2105 USB-to-UART bridge for the console and + for MCUboot serial recovery. The nRF5340's own USB pins are not connected. +- **Indicators and controls:** one RGB LED, one white LED, one push button and an on/off + slide switch. +- **Debug:** 10-pin 1.27 mm SWD header. +- **Board:** 27.7 mm x 39.5 mm, six-layer PCB. + +--- + +## 2. Block diagram + +![AkidaTag block diagram](images/akidatag-block-diagram.svg) + +The nRF5340 owns every peripheral. The AKD1500 is a slave on the nRF5340's SPIM4 bus and +in turn masters its own NOR flash; the nRF5340 reaches that flash through the AKD1500's +feed-through on the second chip select. Power enters from USB-C or the battery, passes +through the charger's power path and the slide switch, and is split into the 1.8 V system +rail, the 0.8 V AKD1500 core rail and the 3.3 V camera rail, with the AKD1500, IMU, +microphone and camera supplies each behind a load switch that the firmware turns on. + +--- + +## 3. Functional description + +### 3.1 Host processor: nRF5340 + +The host is a Nordic nRF5340 system-on-chip (NRF5340-QKAA-R7, aQFN94 package). Its +application core runs the AkidaTag firmware, a Zephyr RTOS application built with the +nRF Connect SDK; its network core runs the Bluetooth Low Energy controller. The firmware +raises the application core to 128 MHz, which SPIM4 needs to reach 32 MHz. + +| Item | Value | Source | +|---|---|---| +| Cores | Two Arm Cortex-M33: application core up to 128 MHz, network core 64 MHz | Nordic nRF5340 product page | +| Application core memory | 1 MB flash, 512 KB RAM | Nordic nRF5340 product page; firmware partition map | +| Network core memory | 256 KB flash, 64 KB RAM | Nordic nRF5340 product page | +| Radio | Bluetooth Low Energy (Bluetooth 5.4 qualified silicon) | Nordic nRF5340 product page | +| High-frequency crystal | 32 MHz (X1) | Rev2 bill of materials | +| Low-frequency crystal | 32.768 kHz (Y1) | Rev2 bill of materials | +| Supply | VDD_1V8 on all VDD pins and VDDH, that is normal-voltage mode at 1.8 V | Rev2 netlist | +| NFC pins | Re-purposed as GPIO for AKD1500 GPIO2 and GPIO3; the firmware programs `nfct-pins-as-gpios` into UICR, a one-time setting | Board overlay, `src/README.md` | +| Application core clock in firmware | 128 MHz (`CONFIG_SYS_CPU_128MHZ`) | `src/Kconfig` | + +The nRF5340's USB interface, VBUS pin and NFC antenna interface are not used on this board. + +### 3.2 AI co-processor: AKD1500 + +The BrainChip AKD1500 is an event-based neuromorphic AI accelerator built on the Akida +neuron fabric. On AkidaTag it is used as an SPI-attached co-processor: the host loads a +compiled model into it, streams pre-processed sensor data in, and reads inference results +back. The chip can learn new classes on the device. + +| Item | Value | Source | +|---|---|---| +| Part | BrainChip AKD-1500, MFCTFBGA169, 7 mm x 7 mm, 0.5 mm ball pitch | AKD1500 product brief V2.4 | +| Process | 22 nm FD-SOI | AKD1500 product brief V2.4 | +| On-chip memory | 1 MB | AKD1500 product brief V2.4 | +| Host interface used | SPI slave, single lane, from nRF5340 SPIM4 | Rev2 netlist; board overlay | +| Memory expansion | SPI master port to NOR flash IC2, quad data lines wired | Rev2 netlist | +| Clock reference | 25 MHz crystal (XTAL1, ABM10W-25.0000MHZ-7-B1U-T3) | Rev2 bill of materials | +| Core clock in firmware | 400 MHz default from the internal 800 MHz PLL; 5 to 400 MHz selectable | `src/Kconfig`, `src/README.md`; product brief gives the 5 to 400 MHz range | +| Host SPI clock in firmware | 8 MHz default, runtime selectable 1 to 32 MHz | `src/Kconfig`, `src/README.md` | +| Supplies | 0.8 V core (VDD_0V8_AKD), 1.8 V I/O (VDD_1V8_AKD); PLL supplies through ferrite beads from the same rails; PCIe PHY supplies tied to ground | Rev2 netlist | +| Strapping | PCIe host select low (SPI host); SEL_CLK low; SPI slave mode pins low; OP_MODE0 low, OP_MODE1 high; TAP_SEL and TESTMODE low | Rev2 netlist | +| Host control lines | SLEEP from P1.07; PWR_GOOD from P1.05 (pulled up on the board); GPIO0..GPIO3 to P1.11, P1.12, P0.02, P0.03 | Rev2 netlist | +| Reset | No host-driven reset line is wired; PCIE_PERST_N is left unconnected | Rev2 netlist | + +Between inferences the firmware asserts SLEEP, which gates the AKD1500 clocks while the +loaded model is retained, and releases it on demand with a reference count. The +`app stop` command additionally turns the AKD1500 PLL off for the lowest idle power. +GPIO3 (P0.03) is the completion interrupt the firmware waits on after each inference. + +### 3.3 Memory + +Two 128 Mbit (16 MB) SPI NOR flash devices are fitted. + +| Device | Bus | Contents | +|---|---|---| +| IC1, on nRF5340 SPIM3 (chip select P0.18) | Single-lane SPI at 8 MHz; the DQ2 and DQ3 lines are pulled up and unused | MCUboot secondary (update) slot, 960 KB, then a LittleFS volume from 0xF0000 to 0x800000 | +| IC2, on the AKD1500 SPI master port | Quad SPI wired from the AKD1500; reached from the nRF5340 through the AKD1500 feed-through on SPIM4 chip select P0.12 | AKD1500 model program and the model metadata records | + +The nRF5340 internal flash holds MCUboot (48 KB at 0x0), the primary application slot +(960 KB from 0xC000, including the 512-byte image header) and 8 KB of settings storage at +0xFC000. Application RAM is 448 KB, with the top 64 KB reserved for the inter-core +channel. Source: `src/pm_static.yml`. + +The firmware's partition map uses the first 8 MB of IC1. Source: `src/pm_static.yml`. + +`TBD: flash part number.` The schematic symbol and placement data name Micron +MT25QU128ABA1EW7, and the firmware identifies both devices by the Micron JEDEC ID; the +Rev2 bill of materials lists Winbond W25Q128JWPIQ for both positions. Which part is fitted +on production boards is being confirmed. + +### 3.4 Audio: microphones + +Two Infineon digital PDM MEMS microphones (U19, U20) share one PDM clock (P1.09) and one +data line (P1.10), each through a 100 ohm series resistor. Their SELECT pins are tied +opposite ways, so each occupies one channel of the stereo PDM frame. They are powered from +the switched VDD_1V8_PDM rail (load switch U8, enable P0.21) through ferrite beads. + +The firmware captures one channel at 16 kHz, 16-bit, with a PDM clock between 1.0 and +1.2 MHz, and sets the PDM gain register directly because the Zephyr DMIC API has no gain +field. Source: `src/core/interface/audio/pdm_mic.c`, `src/include/audio/pdm_mic.h`. + +`TBD: microphone part number.` The Rev2 bill of materials lists IM73D122V01XTMA1; the +repository's notes describe the fitted microphone as an IM69D130 and the firmware gain was +set against that part. + +### 3.5 Motion: inertial measurement unit + +An STMicroelectronics ISM330DHCX six-axis accelerometer and gyroscope (U5) sits on I2C1 +(SCL P1.03, SDA P1.02, 400 kHz) at address 0x6A, with INT1 to P0.31 and INT2 to P1.00. It +is powered from the switched VDD_1V8_ACC rail (load switch U4, enable P0.20). + +The firmware defaults are 208 Hz output data rate for both sensors, plus or minus 8 g +accelerometer full scale and plus or minus 500 degrees per second gyroscope full scale, in +polling mode with FIFO batching. Source: `src/imu_app.conf`, `src/Kconfig`. + +### 3.6 Camera and expansion header + +J1 is a 10-pin, 1.27 mm pitch header intended for an SPI camera. Its four SPI signals +pass through two SN74AXC2T245 bidirectional level shifters (U14, U15) whose A side is +VDD_1V8 and whose B side is the 3.3 V rail, and whose output enable is driven by P1.15. +The header's supply pins are fed by load switch U2 (enable P1.06) from the 3.3 V LDO +output; a 1.8 V option exists through unpopulated resistors. + +The firmware drives an ArduCam Mega camera and supports 96 x 96 and 128 x 128 RGB +frames. Source: `src/README.md`, `src/include/camera/spi_camera.h`. + +See section 5.3 for the pinout and section 4 for a difference between the header's wiring +and the pins the current firmware uses. + +### 3.7 Wireless + +The nRF5340 ANT pin is matched with a 2.2 nH inductor and shunt capacitor to an Abracon +AMCA31-2R450G-S1F-T3 2.4 GHz chip antenna (AE1) through a fitted 0 ohm link (R8). A +U.FL receptacle footprint (J3) is on the board, connected through R9, which is not fitted. +Source: Rev2 netlist and bill of materials. + +Bluetooth Low Energy behaviour is set by the firmware; see section 8. + +`TBD: radio range.` `TBD: transmit power setting.` + +### 3.8 USB-C and console + +J5 is a USB Type-C receptacle. Both CC pins carry 5.1 kilohm pull-downs, so the port +presents as a sink, and VBUS feeds the charger input and the CP2105 through a ferrite bead +(L11). D+ and D- go to a Silicon Labs CP2105 dual USB-to-UART bridge (U6) behind an +SP0503 TVS array. Only the CP2105's standard port (SCI) is wired: its RXD receives the +nRF5340 console transmit (P0.29) and its TXD drives the nRF5340 receive (P1.04). The +enhanced port (ECI) is unconnected, which is why the board presents two serial ports of +which only one carries data. + +The console runs at 115200 baud, 8N1, and is the Zephyr shell of the application. The +same UART is the MCUboot serial recovery channel: at every boot MCUboot listens for about +one second for an mcumgr command, so firmware can be updated over the cable with no button +and no probe. Source: `src/sysbuild/mcuboot.conf`, +[firmware update over USB](../firmware-update-over-usb.md). + +### 3.9 Debug: SWD + +J2 is a 10-pin, 1.27 mm pitch header carrying SWDIO, SWDCLK and reset, with ESD diodes +on all three lines. Its pinout is in section 5.4. The board's reference voltage on this +header is VDD_1V8. + +### 3.10 Indicators and controls + +| Item | Part | Drive | Host pin | +|---|---|---|---| +| RGB LED red | D1 (Würth 150505M173300, common anode to VCC_SYS) | NPN transistor Q2, active high | P1.14 | +| RGB LED green | D1 | Q3, active high | P0.27 | +| RGB LED blue | D1 | Q1, active high | P1.13 | +| White LED | LED1 (Inolux IN-S42ATUW, anode to VCC_SYS) | Q4, active high | P0.28 | +| Push button | SW1, tactile, to ground with a 10 kilohm pull-up to VDD_1V8 | Input, active low | P1.01 | +| On/off switch | SW2, slide, in series between the charger SYS output and VCC_SYS | Not readable by the host | none | + +Source: Rev2 netlist and bill of materials. See section 4 for how the current firmware maps +its LED states onto these pins. + +### 3.11 Power subsystem + +![AkidaTag power tree](images/akidatag-power-tree.svg) + +| Stage | Part | Input | Output | Notes | +|---|---|---|---|---| +| Charger and power path | Texas Instruments BQ25185 (U13) | VBUS 5 V | SYS to the board, BAT to the battery | STAT1 and STAT2 to P0.23 and P0.24; charge current and input limit set by R85 (560 ohm) and R84 (13 kilohm); a 10 kilohm NTC on the TS pin | +| Fuel gauge | Texas Instruments BQ27427 (U12) | In the battery path | I2C1 address 0x55, SOC interrupt (GPOUT) to P0.30 | Impedance Track gauge; the firmware writes design capacity and taper parameters at start-up | +| On/off | SW2 slide switch | SYS | VCC_SYS | Disconnects the whole board except the charger | +| 1.8 V rail | Texas Instruments TPS631000 buck-boost (U1) | VCC_SYS | VDD_1V8 | Feeds the nRF5340, the CP2105 I/O, flash IC1, the pull-ups and the four 1.8 V load switches; passes through the 0.1 ohm shunt R55 read by INA190 U18 | +| 0.8 V rail | Texas Instruments TLV62585 buck (U11) | VCC_SYS | VDD_0V8_AKD | AKD1500 core; enabled by P0.22 through load switch U9; passes through the 0.02 ohm shunt R28 read by INA190 U17 | +| 3.3 V rail | Texas Instruments TPS7A2033 LDO (U16) | VCC_SYS | EXT_VDD_3V3 | Camera level shifter B side and, through load switch U2, the camera header | +| Switched 1.8 V rails | Texas Instruments TPS22991 load switches U10, U4, U8 | VDD_1V8 | VDD_1V8_AKD, VDD_1V8_ACC, VDD_1V8_PDM | Enables P0.19, P0.20, P0.21, each with a 100 kilohm pull-down so a rail is off until the firmware turns it on | +| Current sense | Texas Instruments INA190A3 (U18, U17), gain 100 V/V | Shunts R55, R28 | P0.04 (AIN0), P0.05 (AIN1) | Read by the nRF5340 SAADC at 12 bits, gain 1/3, internal reference | + +Source: Rev2 schematic, netlist and bill of materials; firmware `src/README.md` and +`src/core/interface/current_ic/current_ic.c`. + +The firmware's power-up order is: 0.8 V AKD1500 core, then the AKD1500 1.8 V rail, then +the IMU, then the microphones, then the camera enable. Source: +`akidatag_peripherals_power_enable()` in `src/core/interface/gpio/gpio.c`. + +The firmware programs the fuel gauge for an 1100 mAh, 4.2 V cell with a 3000 mV +terminate voltage and a 4150 mV taper voltage, and the source notes that these values are +for a test battery. `TBD: production battery capacity and chemistry.` + +--- + +## 4. Pin assignment + +The table lists every nRF5340 GPIO as wired on hardware revision 2, and how the firmware on +`main` uses it. Rows marked **differs** are places where the firmware's board definition +still describes the previous board revision; they are listed together after the table. + +| nRF5340 pin | Rev2 signal | Connected to | Firmware use on `main` | +|---|---|---|---| +| P0.00 / XL1 | XL1 | 32.768 kHz crystal Y1 | Low-frequency crystal | +| P0.01 / XL2 | XL2 | 32.768 kHz crystal Y1 | Low-frequency crystal | +| P0.02 / NFC1 | AKD_GPIO2 | AKD1500 GPIO_02, test point TP16 | Not used | +| P0.03 / NFC2 | AKD_GPIO3 | AKD1500 GPIO_03 | `akd_async` input, inference-complete interrupt | +| P0.04 / AIN0 | I1V8_AIN0 | INA190 U18 output (1.8 V rail current), TP7 | SAADC channel 0 | +| P0.05 / AIN1 | I0V8_AIN1 | INA190 U17 output (0.8 V rail current), TP6 | SAADC channel 1 | +| P0.06 / AIN2 | CAM_SPI_CLK | Level shifter U15 to J1 pin 3 | Not used, **differs** (camera SCK expected on P0.17) | +| P0.07 / AIN3 | CAM_SPI_MOSI | Level shifter U15 to J1 pin 5 | Not used, **differs** (camera MOSI expected on P0.13) | +| P0.08 | HSPI_SCK | AKD1500 SPI_S_SCK, TP5 | SPIM4 SCK, high drive | +| P0.09 | HSPI_MOSI | AKD1500 SPI_S_IO0 | SPIM4 MOSI | +| P0.10 | HSPI_MISO | AKD1500 SPI_S_IO1 | SPIM4 MISO | +| P0.11 | HSPI_CS0 | AKD1500 SPI_S_CS_N, 10 kilohm pull-up | SPIM4 chip select 0, AKD1500 | +| P0.12 | HSPI_CS1 | AKD1500 SPI_S_2MCS0_N, 10 kilohm pull-up | SPIM4 chip select 1, flash IC2 through the feed-through | +| P0.13 | QSPI_IO0_MOSI | Flash IC1 DQ0 | SPIM3 MOSI | +| P0.14 | QSPI_IO1_MISO | Flash IC1 DQ1 | SPIM3 MISO | +| P0.15 | QSPI_IO2 | Flash IC1 W#/DQ2, pull-up | Not used | +| P0.16 | QSPI_IO3 | Flash IC1 HOLD#/DQ3, pull-up | Not used | +| P0.17 | QSPI_CLK | Flash IC1 C, TP4 | SPIM3 SCK | +| P0.18 | QSPI_CS_0 | Flash IC1 S#, pull-up | SPIM3 chip select 1 (application), chip select 0 (MCUboot) | +| P0.19 | VDD_1V8_AKD_EN | Load switch U10 ON, 100 kilohm pull-down | `akd_enb` output | +| P0.20 | VDD_1V8_ACC_EN | Load switch U4 ON, pull-down | `acc_enb` output | +| P0.21 | VDD_1V8_PDM_EN | Load switch U8 ON, pull-down | `pdm_enb` output | +| P0.22 | VDD_0V8_AKD_EN | Load switch U9 ON, then TLV62585 EN | `akd_0v_enb` output | +| P0.23 | CHGR_STS1 | BQ25185 STAT1, 10 kilohm pull-up | `chgr_sts1` input | +| P0.24 | CHGR_STS2 | BQ25185 STAT2, pull-up | `chgr_sts2` input | +| P0.25 / AIN4 | CAM_SPI_CS | Level shifter U14 to J1 pin 6, 10 kilohm pull-up | SPIM3 chip select 0, camera | +| P0.26 / AIN5 | CAM_SPI_MISO | Level shifter U14 from J1 pin 4 | `user_btn` input, **differs** (no button on this pin) | +| P0.27 / AIN6 | LED_G | Q3, RGB LED green | `led_green` output | +| P0.28 / AIN7 | LED_W_1 | Q4, white LED | `led_red` output, **differs** (drives the white LED); MCUboot DFU LED | +| P0.29 | DBG_TXD | CP2105 RXD_SCI, TP11 | UART0 TX | +| P0.30 | INT_FL_GAUG | BQ27427 GPOUT, pull-up | `fg_int` input | +| P0.31 | ACC_INT1 | ISM330DHCX INT1 | `imui` input | +| P1.00 | ACC_INT2 | ISM330DHCX INT2 | Not used | +| P1.01 | USER_IO | Push button SW1, 10 kilohm pull-up | MCUboot DFU button only, **differs** (the application's button is defined on P0.26) | +| P1.02 | ACC_FG_SDA | ISM330DHCX SDA, BQ27427 SDA, 2.2 kilohm pull-up | I2C1 SDA | +| P1.03 | ACC_FG_SCL | ISM330DHCX SCL, BQ27427 SCL, 2.2 kilohm pull-up | I2C1 SCL | +| P1.04 | DBG_RXD | CP2105 TXD_SCI, TP13 | UART0 RX | +| P1.05 | AKD_PGOOD | AKD1500 PWR_GOOD through R47, 10 kilohm pull-up to VDD_1V8_AKD, TP1 | Not used | +| P1.06 | CAM_PWR_EN | Load switch U2 ON (camera 3.3 V), 100 kilohm pull-down | Not used, **differs** (camera header power is never enabled) | +| P1.07 | AKD_LP | AKD1500 SLEEP through R48 | `akd_lp` output, sleep control | +| P1.08 | not connected | | Not used on this board | +| P1.09 | PDM_PCLK | Microphones U19 and U20 CLOCK | PDM clock | +| P1.10 | PDM_PDAT | Microphones U19 and U20 DATA, 100 ohm each | PDM data | +| P1.11 | AKD_GPIO0 | AKD1500 GPIO_00 | Not used | +| P1.12 | AKD_GPIO1 | AKD1500 GPIO_01 | Not used | +| P1.13 | LED_B | Q1, RGB LED blue | `akdreset` node, unused by code, **differs** | +| P1.14 | LED_R | Q2, RGB LED red | Not used, **differs** (the firmware's red indication is on P0.28) | +| P1.15 | CAM_SPI_EN | Level shifters U14 and U15 output enable, pull-down | `cam_enb` output | + +Dedicated pins: SWDIO and SWDCLK to J2; RESET to J2 pin 6; ANT to the antenna matching +network; D+, D- and VBUS not connected. Source: Rev2 netlist joined with the nRF5340 ball +map; firmware `src/boards/nrf5340_cpuapp_akidatag.overlay` and +`src/sysbuild/mcuboot_akidatag.overlay`. + +**Differences between the revision 2 wiring and the firmware on `main`.** The firmware's +board definition predates this revision in five places: the camera SPI lines (it shares the +flash bus on P0.17, P0.13 and P0.14, where revision 2 wires the camera to P0.06, P0.07 and +P0.26), the camera supply enable on P1.06 (never driven), the push button (defined on +P0.26, wired on P1.01), the LEDs (the firmware's red LED is the white LED on P0.28; the RGB +red and blue on P1.14 and P1.13 are not driven), and the `akdreset` node on P1.13, which is +the blue LED. `TBD: firmware alignment with revision 2.` The pin table above is the +hardware; the firmware column will be updated when the firmware is. + +--- + +## 5. Connectors + +### 5.1 J5, USB Type-C receptacle + +Würth Elektronik 632722200211, 24-pin. VBUS, D+, D-, CC1, CC2, GND and the shell are used. +The two CC pins have 5.1 kilohm pull-downs (sink). The shell is tied to a separate chassis +net through a ferrite bead. Source: Rev2 netlist and bill of materials. + +### 5.2 J4, battery connector + +JST XH series, 2-pin, 2.5 mm pitch (B2B-XH-A). Pin 1 is VCC_BAT (battery positive, through +the BQ27427 sense path to the charger), pin 2 is GND. Source: Rev2 netlist and bill of +materials. + +`TBD: battery connector mating part.` The bill of materials lists a JST-SM pigtail as the +mating cable, which is a different JST series from the XH receptacle on the board. + +### 5.3 J1, camera header + +10-pin, 2 x 5, 1.27 mm pitch (CNC Tech 3221-10-0100-00). Signals are on the 3.3 V side of +the level shifters. Source: Rev2 netlist. + +| Pin | Signal | Pin | Signal | +|---|---|---|---| +| 1 | VDD_3V3_1V8_CAM (switched supply) | 2 | VDD_3V3_1V8_CAM | +| 3 | SPI CLK | 4 | SPI MISO | +| 5 | SPI MOSI | 6 | SPI CS | +| 7 | not connected | 8 | not connected | +| 9 | GND | 10 | GND | + +### 5.4 J2, SWD header + +10-pin, 2 x 5, 1.27 mm pitch. Source: Rev2 netlist. + +| Pin | Signal | Pin | Signal | +|---|---|---|---| +| 1 | VDD_1V8 (target reference) | 2 | SWDIO | +| 3 | GND | 4 | SWDCLK | +| 5 | GND | 6 | nRESET | +| 7 | not connected | 8 | not connected | +| 9 | GND | 10 | not connected | + +### 5.5 J3, U.FL + +Hirose U.FL-R-SMT-1(80) footprint on the antenna feed, connected through R9. R9 is not +fitted, so the connector is not part of the default build. Source: Rev2 netlist and bill +of materials. + +### 5.6 Test points + +TP1 through TP20 are 1 mm surface-mount test points. Those on host signals: TP1 AKD1500 +PWR_GOOD, TP4 flash IC1 clock, TP5 AKD1500 host SPI clock, TP6 and TP7 the two INA190 +outputs, TP11 and TP13 the console TX and RX, TP16 AKD1500 GPIO2. Rail test points: TP3 +VDD_1V8, TP8 VDD_1V8_AKD, TP9 VDD_1V8_ACC, TP12 VDD_1V8_PDM, TP17 VDD_0V8_AKD, TP2 +camera supply, TP18 VCC_BAT. TP10, TP14 and TP15 are on the AKD1500 SPI master port. +Source: Rev2 netlist. + +--- + +## 6. Electrical characteristics + +No board-level electrical characterisation is available in the sources this page is +built from. The rows below record what the design sets; every measured value is marked. + +### 6.1 Absolute maximum ratings + +| Parameter | Value | +|---|---| +| USB VBUS input | `TBD: absolute maximum VBUS` | +| Battery voltage | `TBD: absolute maximum battery voltage` | +| Voltage on any header pin | `TBD: absolute maximum header voltage` | +| Storage temperature | `TBD: storage temperature range` | + +### 6.2 Recommended operating conditions + +| Parameter | Min | Typ | Max | Unit | Source | +|---|---|---|---|---|---| +| USB input voltage | | 5 | | V | Rev2 schematic (VBUS 5 V) | +| Battery voltage (VCC_SYS) | 3.0 | | 4.2 | V | Rev2 schematic power block diagram | +| VDD_1V8 system rail | | 1.8 | | V | Rev2 schematic | +| VDD_0V8_AKD core rail | | 0.8 | | V | Rev2 schematic | +| EXT_VDD_3V3 camera rail | | 3.3 | | V | Rev2 schematic | +| Camera header supply | | 3.3 (1.8 option not fitted) | | V | Rev2 netlist | +| Operating temperature | `TBD: operating temperature range` | | | | | + +### 6.3 Current consumption + +| Condition | Value | +|---|---| +| Sleep, Bluetooth advertising | `TBD: sleep current` | +| Bluetooth connected, idle | `TBD: idle current` | +| Keyword spotting running | `TBD: keyword spotting current` | +| Peak during inference | `TBD: peak inference current` | +| Charging current from USB | `TBD: charge current` | + +The firmware can measure the 1.8 V and 0.8 V rails itself through the INA190 amplifiers +(`power read`, `power measure`); the shunt values are 0.1 ohm on the 1.8 V rail and +0.02 ohm on the 0.8 V rail and the fitted amplifier gain is 100 V/V. Source: Rev2 bill of +materials, `src/README.md`. + +--- + +## 7. Power modes + +The firmware has no single "power mode" register; the states below are what the sources +describe. + +| State | What is on | Source | +|---|---|---| +| Off | SW2 open: nothing after the charger is powered. The charger still charges the battery from USB. | Rev2 schematic | +| Idle, advertising | nRF5340 running the application with Zephyr device power management; AKD1500 in SLEEP (clocks gated, model retained); microphone, IMU and camera rails as left by the application | `src/prj.conf`, `gpio.c` | +| Application stopped (`app stop`) | As idle, and the AKD1500 PLL turned off | `src/README.md` | +| Inference | AKD1500 woken through SLEEP for each inference, host SPI at the configured clock, microphone capture running | `src/README.md`, `gpio.c` | +| Serial recovery | MCUboot only, listening on the console UART | `src/sysbuild/mcuboot.conf` | + +Battery life in each state: `TBD: battery life`. + +--- + +## 8. Firmware interfaces + +| Interface | Detail | Source | +|---|---|---| +| Bluetooth device name | `AkidaTag` (`AkidaTag-DK` on the development-kit build) | `src/prj.conf`, `src/boards/dk.conf` | +| Bluetooth role and security | Peripheral; LE Secure Connections only, MITM protection required, bonding with up to 3 bonds, 128-bit keys, resolvable private address rotated every 900 s | `src/prj.conf` | +| Advertising | Flags, complete device name, manufacturer-specific data; the device serial is never advertised | `ble_initialization.c` | +| Model transfer service | `f000aa00-0451-4000-b000-000000000000`, one flash sector per stage with an absolute offset in every write | [BLE model transfer](../ble-model-transfer.md) | +| Edge learning service | `f000bb11-0111-9000-c000-000000000000` (command `f000bb10`, acknowledgement `f000bb12`) | `edge_learning.c` | +| Command and streaming channel | Nordic UART Service frames, including battery state of charge and charger status | `src/README.md`, `battery_service.c` | +| Firmware update over Bluetooth | MCUmgr SMP over Bluetooth with the image, OS and statistics groups; MCUboot with RSA-3072 signatures, two updateable images (application and network core) | `src/prj.conf`, `src/sysbuild/mcuboot.conf` | +| Firmware update over USB-C | MCUboot serial recovery on the CP2105 UART, entered without a button | [firmware update over USB](../firmware-update-over-usb.md) | +| Console | Zephyr shell on UART0 at 115200 8N1 | `src/prj.conf`, board overlay | +| Watchdog | 8 s application watchdog | `src/prj.conf` | +| Firmware version | 1.2.0+0, readable over Bluetooth with `smpmgr image state-read` | `VERSION`, `AGENTS.md` | + +--- + +## 9. Mechanical + +![AkidaTag board outline, top view](images/akidatag-board-outline.svg) + +| Item | Value | Source | +|---|---|---| +| Board size | 27.7 mm x 39.5 mm | Rev2 board outline (DXF) | +| Corners | 0.889 mm chamfer on all four corners | Rev2 board outline (DXF) | +| Layer count | 6 | Rev2 fabrication artwork layer set | +| Mounting holes | None found in the outline data; `TBD: mounting provisions` | Rev2 board outline (DXF) | +| USB-C position | Bottom side, centred near one short edge, receptacle projecting beyond the edge | Rev2 placement data | +| Microphones | Bottom side, one in each corner beside the USB-C edge | Rev2 placement data | +| Board thickness | `TBD: board thickness` | | +| Weight | `TBD: weight` | | +| Enclosure | `TBD: enclosure dimensions and material` | | + +--- + +## 10. Environmental and compliance + +| Item | Value | +|---|---| +| Operating temperature | `TBD: operating temperature range` | +| Storage temperature | `TBD: storage temperature range` | +| Humidity | `TBD: humidity range` | +| Regulatory | `TBD: regulatory approvals` | +| Bluetooth qualification | `TBD: Bluetooth qualification` | +| RoHS | The Rev2 bill of materials marks every listed part RoHS compliant except the nRF5340 line, which is blank; `TBD: board-level RoHS statement` | + +--- + +## 11. Ordering information + +| Item | Value | +|---|---| +| Product name | AkidaTag | +| Part number | `TBD: orderable part number` | +| What is in the box | `TBD: box contents` | +| Where to order | `TBD: ordering channel` | + +--- + +## 12. Revision history + +### Hardware + +| Revision | Design | Changes | +|---|---|---| +| 2 | NRF-AKD1500-002 (V-002), schematic V11, changes dated 2026-07-07, released 2026-08-25 | Test pads added on the ADC inputs; INA190 changed to the gain-100 variant with matching shunts; camera signals brought to a header; LDO added for the camera supply; new level-shifter part for the camera signals; SWD connector added; one RGB LED added; on/off switch added; one user button added | +| 1 | V-001, initial release dated 2025-12-24 | `TBD: revision 1 description` | + +Source: the revision summary on the Rev2 schematic cover sheet. + +### Document + +| Date | Change | +|---|---| +| 2026-09-25 | First draft from the revision 2 design files and firmware 1.2.0+0 | + +--- + +## 13. Sources + +- Revision 2 design files: schematic SI-NRF-AKD_BRD-002 V11 (2026-08-25), bill of + materials NRF-AKD1500-002 V11, netlist report (2026-08-24), placement file, board + outline DXF and fabrication artwork set. +- Firmware on `main` at 1.2.0+0: `src/boards/nrf5340_cpuapp_akidatag.overlay`, + `src/sysbuild/mcuboot_akidatag.overlay`, `src/sysbuild/mcuboot.conf`, `src/prj.conf`, + `src/Kconfig`, `src/pm_static.yml`, `src/apps/demo_apps/custom_app.conf`, + `src/imu_app.conf`, `src/README.md`, `src/core/interface/gpio/gpio.c`, + `src/core/interface/audio/pdm_mic.c`, `src/core/interface/ble_services/`, + `src/include/fuel_gauge/fuel_gauge.h`, `docs/ble-model-transfer.md`, + `docs/firmware-update-over-usb.md`, `AGENTS.md`. +- [AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf). +- [Nordic Semiconductor nRF5340 product page](https://www.nordicsemi.com/Products/nRF5340). + +--- + +TBD: footer diff --git a/docs/hardware/images/akidatag-block-diagram.svg b/docs/hardware/images/akidatag-block-diagram.svg new file mode 100644 index 0000000..a80a222 --- /dev/null +++ b/docs/hardware/images/akidatag-block-diagram.svg @@ -0,0 +1,155 @@ + +AkidaTag Rev2 block diagram + + + + + +AkidaTag block diagram (hardware revision 2) + +USB-C receptacle J5 +5 V in, USB 2.0 data + +CP2105 USB to UART +one port used: +console + serial recovery + +SWD header J2 +10-pin 1.27 mm + +2.4 GHz chip antenna +U.FL footprint (not fitted) + +2 x PDM MEMS +microphones +shared clock and data + +ISM330DHCX +6-axis IMU +INT1 to GPIO + +BQ27427 +battery fuel gauge +SOC interrupt to GPIO + +16 MB SPI NOR flash IC1 +firmware update slot ++ LittleFS file system + +Nordic nRF5340 +dual Arm Cortex-M33 +128 MHz application core +64 MHz network core (Bluetooth LE) +1 MB flash, 512 KB RAM + +runs Zephyr / nRF Connect SDK +MCUboot, LittleFS, BLE services + +RGB LED D1 +white LED LED1 +4 GPIO, low side + +Push button SW1 +Power switch SW2 +(slide switch) + +16 MB SPI NOR flash IC2 +model storage on the +AKD1500 SPI master port + +BrainChip AKD1500 +Akida neuromorphic +AI co-processor +SPI slave host interface +25 MHz crystal, PLL +core clock up to 400 MHz +1 MB on-chip memory +0.8 V core, 1.8 V I/O + +Camera header J1 +10-pin 1.27 mm, level-shifted SPI +(2 x SN74AXC2T245), switched 3.3 V + +2 x INA190 current sense +1.8 V rail and 0.8 V rail +into the nRF5340 ADC + +Battery connector J4 +single-cell Li-ion +JST XH, 2-pin + +BQ25185 charger +with power path +STAT1/STAT2 to GPIO + +SW2 +on / off +slide switch + +Regulators +TPS631000 buck-boost 1.8 V (VDD_1V8) +TLV62585 buck 0.8 V, TPS7A2033 LDO 3.3 V + +5 x TPS22991 load switches +AKD 1.8 V, IMU, mics, camera +3.3 V, AKD 0.8 V enable + + +USB 2.0 + + +UART0, 115200 8N1 + + +SWD + + +ANT + + +PDM + + + +I2C1, 400 kHz + + +SPIM3, CS1 + + + + +SPIM4 host SPI + +8 MHz default, up to 32 MHz + +CS0 AKD1500, CS1 flash + + +SLEEP, PWR_GOOD + +GPIO0..3, async IRQ + + +SPI master, quad + + +SPI + enable + + +SAADC + + +VBUS 5 V + + + +SYS + + +VCC_SYS + + + +power enables (5 GPIO) + diff --git a/docs/hardware/images/akidatag-board-outline.svg b/docs/hardware/images/akidatag-board-outline.svg new file mode 100644 index 0000000..f779644 --- /dev/null +++ b/docs/hardware/images/akidatag-board-outline.svg @@ -0,0 +1,68 @@ + +AkidaTag Rev2 board outline, top view + + + + + +AkidaTag board outline, top view (hardware revision 2) + + +nRF5340 + +AKD1500 + +IC1 + +IC2 + +J1 + +J2 + +J3 + +ANT + +D1 + + + +IMU + +CP2105 + +FG + +CHG + +SW1 +LED1 + +USB-C J5 + +J4 battery + +SW2 on/off + +mic + +mic + + + +39.5 mm + + + +27.7 mm +0.889 mm +chamfer x4 + + +top-side part + +bottom-side part +6-layer PCB, no mounting +holes in the outline data + diff --git a/docs/hardware/images/akidatag-power-tree.svg b/docs/hardware/images/akidatag-power-tree.svg new file mode 100644 index 0000000..c031b41 --- /dev/null +++ b/docs/hardware/images/akidatag-power-tree.svg @@ -0,0 +1,95 @@ + +AkidaTag Rev2 power tree + + + + + +AkidaTag power tree (hardware revision 2) + +USB-C J5 +VBUS 5 V + +Battery J4 +single-cell Li-ion +3.0 to 4.2 V + +BQ25185 +linear charger +with power path + +BQ27427 +fuel gauge +(in the battery path) + +SW2 +on / off +slide switch + +TPS631000 buck-boost +VDD_1V8 (1.8 V) + +TLV62585 buck +VDD_0V8_AKD (0.8 V) + +TPS7A2033 LDO +EXT_VDD_3V3 (3.3 V) + +LED anodes +RGB LED D1, white LED1 + +nRF5340 +CP2105, flash IC1 + +U10: VDD_1V8_AKD +AKD1500 I/O, flash IC2 + +U4: VDD_1V8_ACC +ISM330DHCX IMU + +U8: VDD_1V8_PDM +2 x PDM microphones + +AKD1500 core +(0.8 V, via 0.02 ohm +INA190 shunt) + +U2: VDD_3V3_1V8_CAM +camera header J1 ++ level shifters + + +5 V + + + +BAT + + +SYS + + + + + +VCC_SYS + +3.0 to 4.2 V + + + + + +0.1 ohm shunt, INA190 U18 + + + +Enables from the nRF5340 +P0.19 U10, P0.20 U4, P0.21 U8, +P0.22 U9, P1.06 U2 + + +P0.22 enables the 0.8 V buck through load switch U9 + +U2, U4, U8, U9 and U10 are TPS22991 load switches; each switched rail stays off until its enable pin is driven high. + diff --git a/docs/hardware/schematic.md b/docs/hardware/schematic.md new file mode 100644 index 0000000..2748099 --- /dev/null +++ b/docs/hardware/schematic.md @@ -0,0 +1,236 @@ +# AkidaTag schematic + +This page is the circuit-level companion to the [datasheet](datasheet.md). It shows how +the parts on the AkidaTag board connect to each other: the system block diagram, the +power tree, every bus between the host and its peripherals, and the configuration the +AKD1500 is strapped into. + +| Document status | | +|---|---| +| Hardware described | AkidaTag hardware revision 2 | +| Status | Draft for review. The full schematic sheets are not yet on this page; see the note at the end. | + +--- + +## 1. System block diagram + +![AkidaTag block diagram](images/akidatag-block-diagram.svg) + +--- + +## 2. Power tree + +![AkidaTag power tree](images/akidatag-power-tree.svg) + +Power enters from the USB-C receptacle J5 (VBUS, 5 V) or from the battery on J4. The +BQ25185 charger's power path produces the SYS node, which reaches the rest of the board +only through the on/off slide switch SW2 as VCC_SYS (3.0 to 4.2 V). VCC_SYS feeds four +things directly: the TPS631000 buck-boost that makes the 1.8 V system rail, the TLV62585 +buck that makes the 0.8 V AKD1500 core rail, the TPS7A2033 LDO that makes the 3.3 V +camera rail, and the anodes of the RGB and white LEDs. + +The 1.8 V rail passes through a 0.1 ohm shunt watched by INA190 U18, then powers the +nRF5340, the CP2105 bridge, flash IC1 and the pull-up resistors, and feeds three TPS22991 +load switches: U10 for the AKD1500 I/O and its flash IC2, U4 for the IMU, and U8 for the +microphones. The 0.8 V buck is enabled through a fourth load switch, U9, and its output +passes through a 0.02 ohm shunt watched by INA190 U17. The 3.3 V rail powers the B side +of the camera level shifters and, through the fifth load switch U2, the camera header. +Each switch has a pull-down on its enable, so every switched rail is off until the +firmware drives the enable high. + +| Enable | nRF5340 pin | Switch | Rail | +|---|---|---|---| +| VDD_1V8_AKD_EN | P0.19 | U10 | VDD_1V8_AKD | +| VDD_1V8_ACC_EN | P0.20 | U4 | VDD_1V8_ACC | +| VDD_1V8_PDM_EN | P0.21 | U8 | VDD_1V8_PDM | +| VDD_0V8_AKD_EN | P0.22 | U9, then TLV62585 EN | VDD_0V8_AKD | +| CAM_PWR_EN | P1.06 | U2 | VDD_3V3_1V8_CAM | + +The battery sits behind the BQ27427 fuel gauge: the charger's BAT pin reaches the gauge's +sense input, and the gauge's BAT pin reaches the connector. The gauge is on I2C1 at +address 0x55 and raises its GPOUT interrupt line to P0.30 when the state of charge +changes. The charger's STAT1 and STAT2 outputs go to P0.23 and P0.24 with pull-ups; a +10 kilohm NTC thermistor is on the charger's TS pin and a second on the gauge's BIN pin. + +--- + +## 3. Buses and signals + +### 3.1 Host to AKD1500: SPIM4 + +| Signal | nRF5340 | AKD1500 | Notes | +|---|---|---|---| +| SCK | P0.08 | SPI_S_SCK | Test point TP5; high-drive pin mode in firmware | +| MOSI | P0.09 | SPI_S_IO0 | | +| MISO | P0.10 | SPI_S_IO1 | | +| CS0 | P0.11 | SPI_S_CS_N | 10 kilohm pull-up to VDD_1V8_AKD | +| CS1 | P0.12 | SPI_S_2MCS0_N | 10 kilohm pull-up; selects the AKD1500's flash through its slave-to-master feed-through | +| SLEEP | P1.07 | SLEEP | Through 0 ohm R48; firmware `akd_lp`, asserted between inferences | +| PWR_GOOD | P1.05 | PWR_GOOD | Through 0 ohm R47; 10 kilohm pull-up to VDD_1V8_AKD; not driven by the firmware | +| GPIO0 | P1.11 | GPIO_00 | Not used by the firmware | +| GPIO1 | P1.12 | GPIO_01 | Not used by the firmware | +| GPIO2 | P0.02 | GPIO_02 | Not used by the firmware; test point TP16 | +| GPIO3 | P0.03 | GPIO_03 | Firmware `akd_async`, inference-complete interrupt | + +The firmware runs this bus at 8 MHz by default and supports up to 32 MHz; the AKD1500's +second chip-select line (SPI_S_2MCS1_N) is pulled up and unused. + +### 3.2 AKD1500 to its flash: SPI master + +| AKD1500 | Flash IC2 | Notes | +|---|---|---| +| SPI_M_CS0_N | S# | 10 kilohm pull-up | +| SPI_M_SCK | C | Test point TP10 | +| SPI_M_IO0..IO3 | DQ0..DQ3 | Quad wiring with 4.7 kilohm pull-ups on the data lines | +| SPI_M_CS1_N | test point TP14 only | Second flash position not fitted | +| SPI_M_SCKX | test point TP15 only | | + +IC2 is powered from VDD_1V8_AKD, so it is off whenever the AKD1500 I/O rail is off. + +### 3.3 Host to flash IC1: SPIM3 + +| Signal | nRF5340 | Flash IC1 | Notes | +|---|---|---|---| +| SCK | P0.17 | C | Test point TP4 | +| MOSI | P0.13 | DQ0 | | +| MISO | P0.14 | DQ1 | | +| CS | P0.18 | S# | 10 kilohm pull-up | +| W#/DQ2 | P0.15 | DQ2 | Pulled up; single-lane operation in firmware | +| HOLD#/DQ3 | P0.16 | DQ3 | Pulled up; single-lane operation in firmware | + +IC1 is on the always-on 1.8 V rail, which is what lets MCUboot read the update slot before +the application has enabled anything. + +### 3.4 I2C1: IMU and fuel gauge + +| Signal | nRF5340 | Devices | Notes | +|---|---|---|---| +| SCL | P1.03 | ISM330DHCX SCL, BQ27427 SCL | 2.2 kilohm pull-up to VDD_1V8_ACC | +| SDA | P1.02 | ISM330DHCX SDA, BQ27427 SDA | 2.2 kilohm pull-up to VDD_1V8_ACC | +| IMU INT1 | P0.31 | ISM330DHCX INT1 | | +| IMU INT2 | P1.00 | ISM330DHCX INT2 | Not used by the firmware | +| Gauge interrupt | P0.30 | BQ27427 GPOUT | 10 kilohm pull-up | + +The IMU's SA0 pin is grounded, giving address 0x6A; the gauge answers at 0x55. The bus +pull-ups hang off the switched IMU rail, so the bus is only pulled up while VDD_1V8_ACC is +enabled. + +### 3.5 PDM: microphones + +| Signal | nRF5340 | Microphones | Notes | +|---|---|---|---| +| CLOCK | P1.09 | U19 CLOCK, U20 CLOCK | | +| DATA | P1.10 | U19 DATA, U20 DATA | 100 ohm series resistor on each microphone | + +U19's SELECT pin is tied to its supply and U20's to ground, so the two microphones occupy +opposite channels of the PDM frame. Both are powered from VDD_1V8_PDM through a ferrite +bead each. + +### 3.6 Camera header J1 + +| Signal | nRF5340 | Level shifter | J1 pin | +|---|---|---|---| +| CLK | P0.06 | U15 A1 to B1 | 3 | +| MOSI | P0.07 | U15 A2 to B2 | 5 | +| MISO | P0.26 | U14 A1 from B1 | 4 | +| CS | P0.25 | U14 A2 to B2 | 6 | +| Output enable | P1.15 | U14 and U15 OE (active low), 100 kilohm pull-downs | | +| Supply enable | P1.06 | Load switch U2 | 1, 2 | + +The shifters' A side is VDD_1V8 and their B side is the 3.3 V rail; a 1.8 V option for +the B side and for the header supply exists through resistors that are not fitted. + +### 3.7 USB-C and console UART + +| Signal | Path | +|---|---| +| VBUS | J5 VBUS pins, TVS, ferrite bead L11, then the charger input and the CP2105 REGIN | +| D+, D- | J5, TVS array D2, CP2105 D+ and D- | +| CC1, CC2 | 5.1 kilohm pull-downs (sink) | +| Console TX | nRF5340 P0.29 to CP2105 RXD_SCI, test point TP11 | +| Console RX | nRF5340 P1.04 from CP2105 TXD_SCI, test point TP13 | +| CP2105 ECI port | Not connected | +| Shell | Chassis net through a ferrite bead | + +### 3.8 SWD header J2 + +| J2 pin | Signal | +|---|---| +| 1 | VDD_1V8 | +| 2 | SWDIO (nRF5340 SWDIO, ESD diode D5, 10 kilohm pull-up) | +| 3, 5, 9 | GND | +| 4 | SWDCLK (nRF5340 SWDCLK, ESD diode D4, 10 kilohm pull-up) | +| 6 | nRESET (nRF5340 RESET, ESD diode D3) | +| 7, 8, 10 | Not connected | + +### 3.9 Radio + +The nRF5340 ANT pin passes through a 2.2 nH series inductor with a 0.1 uF shunt to a +fitted 0 ohm link (R8) into the chip antenna AE1. A second link (R9, not fitted) leads to +the U.FL footprint J3. + +### 3.10 LEDs and controls + +| Signal | nRF5340 | Circuit | +|---|---|---| +| LED_R | P1.14 | Q2 base; D1 red cathode through 500 ohm | +| LED_G | P0.27 | Q3 base; D1 green cathode through 249 ohm | +| LED_B | P1.13 | Q1 base; D1 blue cathode through 249 ohm | +| LED_W_1 | P0.28 | Q4 base; LED1 cathode through 270 ohm | +| USER_IO | P1.01 | SW1 to ground, 10 kilohm pull-up to VDD_1V8 | + +D1's common anode and LED1's anode are on VCC_SYS. Q1 to Q4 are pre-biased NPN +transistors (DTC043ZUB), so each LED is on when its host pin is high. + +### 3.11 Current sense + +| Rail | Shunt | Amplifier | nRF5340 | +|---|---|---|---| +| VDD_1V8 | R55, 0.1 ohm | INA190A3 U18, gain 100 V/V | P0.04 (AIN0), test point TP7 | +| VDD_0V8_AKD | R28, 0.02 ohm | INA190A3 U17, gain 100 V/V | P0.05 (AIN1), test point TP6 | + +Both amplifiers run from VDD_1V8 with their enable pins tied high. + +--- + +## 4. AKD1500 configuration + +| Pin | Board setting | Meaning on this board | +|---|---|---| +| PCIE_HOST_SEL | Low (0 ohm to ground; pull-up not fitted) | SPI host interface selected | +| SEL_CLK | Low (0 ohm to ground; pull-up not fitted) | Crystal reference on OSC_XI and OSC_XO | +| SPI_S_MODE0, SPI_S_MODE1 | Low, low (0 ohm to ground; pull-ups not fitted) | Single-lane SPI slave | +| OP_MODE0 | Low (0 ohm to ground; pull-up not fitted) | `TBD: OP_MODE meaning` | +| OP_MODE1 | High (10 kilohm to VDD_1V8_AKD; pull-down not fitted) | `TBD: OP_MODE meaning` | +| TAP_SEL, TESTMODE | Low (0 ohm to ground) | Test access off | +| PCIE_PERST_N | Not connected (resistor not fitted) | PCIe unused | +| PCIe receive lanes and reference clock inputs | Tied to ground | PCIe unused | +| PCIe transmit lanes | Not connected | PCIe unused | +| PCIe PHY supplies (VP, VPH, VPTX0, VPTX1) | 0 ohm to ground | PCIe unused | +| RESREF | 200 ohm to ground | Reference resistor | +| Crystal | 25 MHz (ABM10W-25.0000MHZ-7-B1U-T3), 7 pF load capacitors, 1 megohm feedback resistor, 0 ohm series link on OSC_XI | | +| PLL supplies | VDDAPLL18 from VDD_1V8_AKD through ferrite bead L8; VDDPLL08 from VDD_0V8_AKD through ferrite bead L9; AVS_PLL to ground | | +| eFuse supplies (VDDIO_EFUSE, VQPS_EFUSE, VPD) | Not connected | Fuse programming unused | + +--- + +## 5. The schematic sheets + +The revision 2 schematic is a twelve-sheet document: cover, power block diagram, two +nRF5340 sheets, three AKD1500 sheets, microphones and LEDs, sensors and camera, USB, +battery and fuel gauge, and power. `TBD: schematic sheets.` Whether the sheets are +published on this page, as images or as a PDF, is being decided; until then this page +carries the derived views above. + +--- + +## Sources + +The revision 2 schematic (SI-NRF-AKD_BRD-002 V11, 2026-08-25), netlist report and bill of +materials, joined with the firmware board overlay +`src/boards/nrf5340_cpuapp_akidatag.overlay`, `src/core/interface/gpio/gpio.c` and +`src/README.md` on `main` at firmware 1.2.0+0. + +--- + +TBD: footer diff --git a/docs/hardware/technical-specifications.md b/docs/hardware/technical-specifications.md new file mode 100644 index 0000000..4b6786e --- /dev/null +++ b/docs/hardware/technical-specifications.md @@ -0,0 +1,152 @@ +# AkidaTag technical specifications + +AkidaTag is a compact, battery-powered edge-AI device that runs neural networks on the +BrainChip AKD1500 Akida neuromorphic processor, listens through on-board microphones, +senses motion, and talks to the BrainChip Connect app over Bluetooth Low Energy. It learns +new keywords on the device itself, with no cloud connection. + +This page is the buyer-facing summary. The engineering reference, with pinouts, the power +tree and the full connector detail, is the [datasheet](datasheet.md). + +| Document status | | +|---|---| +| Hardware described | AkidaTag hardware revision 2 | +| Firmware referenced | AkidaTag firmware 1.2.0+0 | +| Status | Draft for review. Every entry marked `TBD:` is awaiting confirmation; nothing here is estimated. | + +--- + +## At a glance + +| | | +|---|---| +| AI processor | BrainChip AKD1500 Akida neuromorphic co-processor with on-device learning | +| Host processor | Nordic nRF5340, dual Arm Cortex-M33, 128 MHz | +| Wireless | Bluetooth Low Energy, on-board antenna | +| Sensors | Two MEMS microphones, six-axis accelerometer and gyroscope | +| Expansion | SPI camera header | +| Power | Rechargeable single-cell Li-ion, USB-C charging, on/off switch | +| Size | 27.7 mm x 39.5 mm board | +| Companion app | BrainChip Connect | + +--- + +## Processing + +| Item | Specification | +|---|---| +| AI co-processor | BrainChip AKD1500, Akida neuron fabric, event-based neuromorphic architecture, 22 nm FD-SOI, 7 mm x 7 mm package | +| AI memory | 1 MB on-chip | +| AI clock | Up to 400 MHz core clock from an on-board 25 MHz crystal; 400 MHz default in firmware | +| On-device learning | Yes; the firmware exposes keyword learning over Bluetooth | +| Host interface to the AI processor | SPI at 8 MHz by default, up to 32 MHz | +| Host processor | Nordic nRF5340: 128 MHz Arm Cortex-M33 application core with 1 MB flash and 512 KB RAM, plus a 64 MHz Arm Cortex-M33 network core for Bluetooth | +| Operating system | Zephyr RTOS, nRF Connect SDK, MCUboot bootloader | + +## Memory + +| Item | Specification | +|---|---| +| Model storage | 16 MB SPI NOR flash dedicated to the AI processor | +| Firmware storage | 16 MB SPI NOR flash for firmware updates and a LittleFS file system, in addition to the host's 1 MB internal flash | + +## Sensors + +| Item | Specification | +|---|---| +| Microphones | Two digital PDM MEMS microphones; the firmware captures audio at 16 kHz, 16-bit | +| Motion | STMicroelectronics ISM330DHCX six-axis accelerometer and gyroscope; firmware defaults 208 Hz, plus or minus 8 g and plus or minus 500 degrees per second | +| Camera | SPI camera header (10-pin, 1.27 mm pitch) with switched 3.3 V supply; the firmware supports an ArduCam Mega camera at 96 x 96 and 128 x 128 pixels | +| Battery monitoring | Fuel gauge reporting state of charge to the app; charger status reporting | +| Power monitoring | On-board current sensing of the 1.8 V system rail and the 0.8 V AI core rail, readable from the firmware console | + +## Connectivity + +| Item | Specification | +|---|---| +| Bluetooth | Bluetooth Low Energy peripheral, device name `AkidaTag`; LE Secure Connections only with bonding; firmware update over Bluetooth | +| Antenna | On-board 2.4 GHz chip antenna | +| Range | `TBD: Bluetooth range` | +| USB | USB-C: 5 V charging input and a USB-to-serial console at 115200 baud; firmware update over the cable with no tools other than a computer | +| Debug | 10-pin 1.27 mm SWD header | + +## Power + +| Item | Specification | +|---|---| +| Battery | Single-cell rechargeable Li-ion, 3.0 to 4.2 V, on a JST XH 2-pin connector | +| Battery capacity | `TBD: battery capacity` | +| Battery life | `TBD: battery life` | +| Charging | On-board linear charger with power path; charges from USB-C 5 V while the device runs | +| Charge time | `TBD: charge time` | +| Power switch | On/off slide switch | +| Power consumption | `TBD: power consumption by mode` | + +## Indicators and controls + +| Item | Specification | +|---|---| +| LEDs | One RGB LED and one white LED under firmware control | +| Buttons | One push button; the on/off slide switch | + +## Physical + +| Item | Specification | +|---|---| +| Board dimensions | 27.7 mm x 39.5 mm, six-layer PCB, chamfered corners | +| Enclosure | `TBD: enclosure dimensions, material and colour` | +| Weight | `TBD: weight` | +| Mounting | `TBD: mounting provisions` | + +## Operating environment + +| Item | Specification | +|---|---| +| Operating temperature | `TBD: operating temperature range` | +| Storage temperature | `TBD: storage temperature range` | +| Humidity | `TBD: humidity range` | +| Ingress protection | `TBD: ingress protection rating` | + +## Software and compatibility + +| Item | Specification | +|---|---| +| Companion app | BrainChip Connect: connects over Bluetooth, loads models onto the device, runs the demonstrations and starts on-device learning | +| Supported phones | `TBD: supported mobile platforms and versions` | +| Firmware | Firmware from this repository; updates over Bluetooth (MCUmgr) or over USB-C from a computer | +| Model tooling | Models built with BrainChip MetaTF from TensorFlow/Keras or PyTorch, then packaged with the model workflow in this repository and sent to the device by the app | +| Demonstrations included | Keyword spotting with on-device edge learning; motion sensing; camera capture from the console | + +## Compliance + +| Item | Specification | +|---|---| +| Regulatory | `TBD: regulatory approvals` | +| Bluetooth qualification | `TBD: Bluetooth qualification` | +| RoHS | `TBD: RoHS statement` | + +## What is in the box + +`TBD: box contents` + +## Ordering + +| Item | Specification | +|---|---| +| Product name | AkidaTag | +| Part number | `TBD: orderable part number` | +| Where to order | `TBD: ordering channel` | + +--- + +## Sources + +Every value on this page is taken from the AkidaTag revision 2 design files, the AkidaTag +firmware 1.2.0+0 in this repository, the +[AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf) +or the [Nordic nRF5340 product page](https://www.nordicsemi.com/Products/nRF5340). The +[datasheet](datasheet.md) lists the source next to each value. + +--- + +TBD: footer From 8d1685fcf512dcff8310ec1bcaab175b10293680 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Fri, 25 Sep 2026 23:49:14 -0700 Subject: [PATCH 2/7] docs(hardware): fill in the reviewed values and public links Answers from the hardware review: the flash and microphone part numbers come from the revision 2 bill of materials, no battery ships with the board, the charger setting is derived from the fitted ISET and ILIM resistors and the BQ25185 datasheet, the radio figures come from the Nordic product specification, and the AKD1500 strap meanings are explained. The schematic page becomes the block diagram page with a redrawn system block diagram grouped the way the earlier diagram was, and every page carries the approved public footer and the Developer Hub, Google Play pre-registration and Discord links. --- .../{schematic.md => block-diagram.md} | 69 ++-- docs/hardware/datasheet.md | 134 +++++--- .../images/akidatag-block-diagram.svg | 323 ++++++++++-------- docs/hardware/technical-specifications.md | 206 +++++------ 4 files changed, 394 insertions(+), 338 deletions(-) rename docs/hardware/{schematic.md => block-diagram.md} (72%) diff --git a/docs/hardware/schematic.md b/docs/hardware/block-diagram.md similarity index 72% rename from docs/hardware/schematic.md rename to docs/hardware/block-diagram.md index 2748099..6bd5d55 100644 --- a/docs/hardware/schematic.md +++ b/docs/hardware/block-diagram.md @@ -1,20 +1,45 @@ -# AkidaTag schematic +# AkidaTag block diagram -This page is the circuit-level companion to the [datasheet](datasheet.md). It shows how -the parts on the AkidaTag board connect to each other: the system block diagram, the -power tree, every bus between the host and its peripherals, and the configuration the -AKD1500 is strapped into. +This page shows how the parts on the AkidaTag board connect to each other: the system +block diagram, the power tree, every bus between the host and its peripherals, and the +configuration the AKD1500 is strapped into. The engineering detail behind each block is in +the [datasheet](datasheet.md); the buyer-facing summary is the +[technical specifications](technical-specifications.md). | Document status | | |---|---| | Hardware described | AkidaTag hardware revision 2 | -| Status | Draft for review. The full schematic sheets are not yet on this page; see the note at the end. | +| Status | Draft for review. Every entry marked `TBD:` is awaiting confirmation; nothing here is estimated. | --- ## 1. System block diagram -![AkidaTag block diagram](images/akidatag-block-diagram.svg) +![AkidaTag system block diagram](images/akidatag-block-diagram.svg) + +The board has seven functional groups. **Compute and memory** is the Nordic nRF5340 +host and the BrainChip AKD1500 AI co-processor, each with its own 16 MB SPI NOR flash. +**Power system** takes 5 V from USB-C or a single-cell Li-ion battery through the BQ25185 +charger and power path, the BQ27427 fuel gauge and the on/off switch, and makes the 1.8 V, +0.8 V and 3.3 V rails. **USB and debug** is the CP2105 USB-to-UART bridge on the USB-C +data lines and the 10-pin SWD header. **RF front-end** is the antenna matching network and +the 2.4 GHz chip antenna. **Sensors** are the ISM330DHCX six-axis IMU on I2C and two PDM +MEMS microphones. **Expansion** is the camera header with a level-shifted SPI bus and a +switched 3.3 V supply. **Indicators and controls** are the RGB LED, the white LED and the +user button. + +### Changes from the earlier diagram + +Revision 2 is the first board shipped, but an earlier system block diagram of the +first revision has circulated, so the differences are worth stating. That board had a +20-pin expansion connector carrying GPIO, I2S, I2C, SPI, USB and UART, three buttons, 4-pin +SWD debug pads, two status LEDs, a fitted U.FL connector and a 42 mm x 30 mm outline. +Revision 2 replaces the expansion connector with the 10-pin camera header, has one button +and an on/off switch, a 10-pin SWD header, an RGB LED and a white LED, an unfitted U.FL +footprint, two current-sense amplifiers, and a 27.7 mm x 39.5 mm outline. The processors, +flashes, radio, IMU, microphones, charger and fuel gauge are the same. Sources: the +revision 2 netlist, bill of materials and board outline; the earlier system block diagram +and labelled layout drawing. --- @@ -189,7 +214,8 @@ transistors (DTC043ZUB), so each LED is on when its host pin is high. | VDD_1V8 | R55, 0.1 ohm | INA190A3 U18, gain 100 V/V | P0.04 (AIN0), test point TP7 | | VDD_0V8_AKD | R28, 0.02 ohm | INA190A3 U17, gain 100 V/V | P0.05 (AIN1), test point TP6 | -Both amplifiers run from VDD_1V8 with their enable pins tied high. +Both amplifiers run from VDD_1V8 with their enable pins tied high. The A3 gain option is +100 V/V per the Texas Instruments INA190 datasheet (SBOS863D). --- @@ -200,8 +226,8 @@ Both amplifiers run from VDD_1V8 with their enable pins tied high. | PCIE_HOST_SEL | Low (0 ohm to ground; pull-up not fitted) | SPI host interface selected | | SEL_CLK | Low (0 ohm to ground; pull-up not fitted) | Crystal reference on OSC_XI and OSC_XO | | SPI_S_MODE0, SPI_S_MODE1 | Low, low (0 ohm to ground; pull-ups not fitted) | Single-lane SPI slave | -| OP_MODE0 | Low (0 ohm to ground; pull-up not fitted) | `TBD: OP_MODE meaning` | -| OP_MODE1 | High (10 kilohm to VDD_1V8_AKD; pull-down not fitted) | `TBD: OP_MODE meaning` | +| OP_MODE0 | Low (0 ohm to ground; pull-up not fitted) | Crystal oscillator is the internal clock source | +| OP_MODE1 | High (10 kilohm to VDD_1V8_AKD; pull-down not fitted) | Safe Mode: the chip stays on the 25 MHz reference after reset and the host switches it onto the PLL once the PLL locks; the firmware does this before raising the host SPI clock, since the host clock must stay at or below a quarter of the AKD1500's SPI slave core clock | | TAP_SEL, TESTMODE | Low (0 ohm to ground) | Test access off | | PCIE_PERST_N | Not connected (resistor not fitted) | PCIe unused | | PCIe receive lanes and reference clock inputs | Tied to ground | PCIe unused | @@ -214,23 +240,16 @@ Both amplifiers run from VDD_1V8 with their enable pins tied high. --- -## 5. The schematic sheets - -The revision 2 schematic is a twelve-sheet document: cover, power block diagram, two -nRF5340 sheets, three AKD1500 sheets, microphones and LEDs, sensors and camera, USB, -battery and fuel gauge, and power. `TBD: schematic sheets.` Whether the sheets are -published on this page, as images or as a PDF, is being decided; until then this page -carries the derived views above. - ---- - ## Sources -The revision 2 schematic (SI-NRF-AKD_BRD-002 V11, 2026-08-25), netlist report and bill of -materials, joined with the firmware board overlay -`src/boards/nrf5340_cpuapp_akidatag.overlay`, `src/core/interface/gpio/gpio.c` and -`src/README.md` on `main` at firmware 1.2.0+0. +The revision 2 schematic (SI-NRF-AKD_BRD-002 V11, 2026-08-25), netlist report, bill of +materials and board outline; the earlier system block diagram and labelled layout +drawing (January 2026); the Texas Instruments INA190 datasheet (SBOS863D); the AKD1500 +datasheet v1.2 ball descriptions and BrainChip application note AN-003 for the strap +meanings; and the firmware board overlay `src/boards/nrf5340_cpuapp_akidatag.overlay`, +`src/core/interface/gpio/gpio.c`, `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp` +and `src/README.md` on `main` at firmware 1.2.0+0. --- -TBD: footer +© 2026 BrainChip Holdings Ltd. All rights reserved. diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index aeeee53..9c60e89 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -9,7 +9,7 @@ application connects to it over Bluetooth to load models and run the demonstrati This page is the engineering reference for the board. The buyer-facing summary is the [technical specifications](technical-specifications.md) page, and the circuit-level view -is the [schematic](schematic.md) page. +is the [block diagram](block-diagram.md) page. | Document status | | |---|---| @@ -41,7 +41,7 @@ is the [schematic](schematic.md) page. 3.3 V supply, used by the firmware with an ArduCam Mega SPI camera. - **Wireless:** Bluetooth Low Energy through an on-board 2.4 GHz chip antenna, with an unpopulated U.FL footprint for a test connector. -- **Power:** single-cell Li-ion battery with a BQ25185 linear charger and power path, a +- **Power:** single-cell Li-ion battery (not supplied) with a BQ25185 linear charger and power path, a BQ27427 fuel gauge, a 1.8 V buck-boost converter, a 0.8 V buck converter for the AKD1500 core, a 3.3 V LDO for the camera header, five load switches under firmware control, and two INA190 current-sense amplifiers feeding the nRF5340 ADC so the @@ -109,14 +109,24 @@ back. The chip can learn new classes on the device. | Core clock in firmware | 400 MHz default from the internal 800 MHz PLL; 5 to 400 MHz selectable | `src/Kconfig`, `src/README.md`; product brief gives the 5 to 400 MHz range | | Host SPI clock in firmware | 8 MHz default, runtime selectable 1 to 32 MHz | `src/Kconfig`, `src/README.md` | | Supplies | 0.8 V core (VDD_0V8_AKD), 1.8 V I/O (VDD_1V8_AKD); PLL supplies through ferrite beads from the same rails; PCIe PHY supplies tied to ground | Rev2 netlist | -| Strapping | PCIe host select low (SPI host); SEL_CLK low; SPI slave mode pins low; OP_MODE0 low, OP_MODE1 high; TAP_SEL and TESTMODE low | Rev2 netlist | +| Strapping | PCIe host select low (SPI host); SEL_CLK low (crystal oscillator); SPI slave mode pins low; OP_MODE0 low (crystal as the clock source); OP_MODE1 high (Safe Mode, see below); TAP_SEL and TESTMODE low | Rev2 netlist; AKD1500 datasheet v1.2 ball descriptions | | Host control lines | SLEEP from P1.07; PWR_GOOD from P1.05 (pulled up on the board); GPIO0..GPIO3 to P1.11, P1.12, P0.02, P0.03 | Rev2 netlist | | Reset | No host-driven reset line is wired; PCIE_PERST_N is left unconnected | Rev2 netlist | Between inferences the firmware asserts SLEEP, which gates the AKD1500 clocks while the loaded model is retained, and releases it on demand with a reference count. The `app stop` command additionally turns the AKD1500 PLL off for the lowest idle power. -GPIO3 (P0.03) is the completion interrupt the firmware waits on after each inference. +GPIO3 (P0.03) is the completion interrupt the firmware waits on after each inference, which +is the pad BrainChip's application note AN-001 recommends for it. The sleep behaviour is +described in AN-002. + +OP_MODE1 is strapped high, which puts the AKD1500 in Safe Mode: after reset it stays on the +25 MHz reference clock instead of switching itself onto its PLL, and the host has to make +that switch once the PLL reports lock. The firmware does this at a low host SPI clock and +only then raises the clock, because the AKD1500 requires the host clock to stay at or below +a quarter of its SPI slave core clock, which caps the host at a few megahertz while the +reference clock is in use. Source: `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp`; +AKD1500 application note AN-003. ### 3.3 Memory @@ -134,25 +144,27 @@ channel. Source: `src/pm_static.yml`. The firmware's partition map uses the first 8 MB of IC1. Source: `src/pm_static.yml`. -`TBD: flash part number.` The schematic symbol and placement data name Micron -MT25QU128ABA1EW7, and the firmware identifies both devices by the Micron JEDEC ID; the -Rev2 bill of materials lists Winbond W25Q128JWPIQ for both positions. Which part is fitted -on production boards is being confirmed. +Both positions are fitted with the Winbond W25Q128JWPIQ (1.8 V, 128 Mbit) listed in the +Rev2 bill of materials. The firmware on `main` still identifies the devices by the JEDEC ID +of the Micron part named in the schematic symbols; it will be aligned with the Winbond part +before the product ships. ### 3.4 Audio: microphones -Two Infineon digital PDM MEMS microphones (U19, U20) share one PDM clock (P1.09) and one -data line (P1.10), each through a 100 ohm series resistor. Their SELECT pins are tied +Two Infineon IM73D122V01XTMA1 digital PDM MEMS microphones (U19, U20) share one PDM clock +(P1.09) and one data line (P1.10), each through a 100 ohm series resistor. Their SELECT pins are tied opposite ways, so each occupies one channel of the stereo PDM frame. They are powered from the switched VDD_1V8_PDM rail (load switch U8, enable P0.21) through ferrite beads. -The firmware captures one channel at 16 kHz, 16-bit, with a PDM clock between 1.0 and -1.2 MHz, and sets the PDM gain register directly because the Zephyr DMIC API has no gain -field. Source: `src/core/interface/audio/pdm_mic.c`, `src/include/audio/pdm_mic.h`. +The firmware captures one channel, the left slot of the PDM frame, at 16 kHz, 16-bit, with +a PDM clock between 1.0 and 1.2 MHz, and sets the PDM gain register directly because the +Zephyr DMIC API has no gain field. The keyword spotting demonstration runs on that single +channel; the second microphone is available to firmware that requests both. Source: +`src/core/interface/audio/pdm_mic.c`, `src/include/audio/pdm_mic.h`. -`TBD: microphone part number.` The Rev2 bill of materials lists IM73D122V01XTMA1; the -repository's notes describe the fitted microphone as an IM69D130 and the firmware gain was -set against that part. +The part number is from the Rev2 bill of materials. The footprint name in the design files +and the notes in this repository still carry the name of a different Infineon part, the +IM69D130. ### 3.5 Motion: inertial measurement unit @@ -187,7 +199,10 @@ Source: Rev2 netlist and bill of materials. Bluetooth Low Energy behaviour is set by the firmware; see section 8. -`TBD: radio range.` `TBD: transmit power setting.` +Nordic specifies the nRF5340 radio for a configurable transmit power of -40 to +3 dBm and +a receiver sensitivity of -98 dBm at 1 Mbps. The firmware does not set a transmit power, so +the Bluetooth controller's default applies. Source: nRF5340 product specification, key +features; `src/prj.conf`. `TBD: transmit power and range measured on this board.` ### 3.8 USB-C and console @@ -211,6 +226,10 @@ J2 is a 10-pin, 1.27 mm pitch header carrying SWDIO, SWDCLK and reset, with ESD on all three lines. Its pinout is in section 5.4. The board's reference voltage on this header is VDD_1V8. +Pin 6 carries nRESET and pin 10 is not connected. That differs from the Arm 10-pin Cortex +Debug layout, which puts SWO on pin 6 and nRESET on pin 10, so a probe's reset line does not +reach the board through a pin-to-pin cable. `TBD: J2 pinout verified on a board.` + ### 3.10 Indicators and controls | Item | Part | Drive | Host pin | @@ -231,7 +250,7 @@ its LED states onto these pins. | Stage | Part | Input | Output | Notes | |---|---|---|---|---| -| Charger and power path | Texas Instruments BQ25185 (U13) | VBUS 5 V | SYS to the board, BAT to the battery | STAT1 and STAT2 to P0.23 and P0.24; charge current and input limit set by R85 (560 ohm) and R84 (13 kilohm); a 10 kilohm NTC on the TS pin | +| Charger and power path | Texas Instruments BQ25185 (U13) | VBUS 5 V | SYS to the board, BAT to the battery | STAT1 and STAT2 to P0.23 and P0.24; R85 (560 ohm) on ISET sets a nominal 536 mA fast-charge current; R84 (13 kilohm) on ILIM/VSET selects 4.2 V battery regulation and a 1100 mA input current limit; a 10 kilohm NTC on the TS pin | | Fuel gauge | Texas Instruments BQ27427 (U12) | In the battery path | I2C1 address 0x55, SOC interrupt (GPOUT) to P0.30 | Impedance Track gauge; the firmware writes design capacity and taper parameters at start-up | | On/off | SW2 slide switch | SYS | VCC_SYS | Disconnects the whole board except the charger | | 1.8 V rail | Texas Instruments TPS631000 buck-boost (U1) | VCC_SYS | VDD_1V8 | Feeds the nRF5340, the CP2105 I/O, flash IC1, the pull-ups and the four 1.8 V load switches; passes through the 0.1 ohm shunt R55 read by INA190 U18 | @@ -243,13 +262,24 @@ its LED states onto these pins. Source: Rev2 schematic, netlist and bill of materials; firmware `src/README.md` and `src/core/interface/current_ic/current_ic.c`. +The charge current follows from the charger's formula (300 A·ohm divided by the ISET +resistor) with a stated accuracy of plus or minus 10 %. The charger precharges at 20 % of +that current while the battery is below 3.0 V, terminates at 10 % of it, and has a 6 hour +safety timer. Source: BQ25185 datasheet SLUSF65B, electrical characteristics and Table 6-1; +Rev2 bill of materials for R84 and R85. + The firmware's power-up order is: 0.8 V AKD1500 core, then the AKD1500 1.8 V rail, then the IMU, then the microphones, then the camera enable. Source: `akidatag_peripherals_power_enable()` in `src/core/interface/gpio/gpio.c`. -The firmware programs the fuel gauge for an 1100 mAh, 4.2 V cell with a 3000 mV -terminate voltage and a 4150 mV taper voltage, and the source notes that these values are -for a test battery. `TBD: production battery capacity and chemistry.` +No battery is supplied with the board. The firmware programs the fuel gauge for an +1100 mAh, 4.2 V cell with a 3000 mV terminate voltage and a 4150 mV taper voltage, and the +source notes that these values are for a test battery, so the state of charge it reports is +only as good as the match between those parameters and the cell fitted. The firmware also +inverts the sign of the gauge's current reading to correct for a sense resistor that the +code describes as physically reversed; the netlist alone cannot show whether revision 2 +still has that orientation. `TBD: fuel gauge sense orientation on revision 2.` Source: +`src/include/fuel_gauge/fuel_gauge.h`, `src/core/interface/fuel_gauge/fuel_gauge.c`. --- @@ -321,8 +351,8 @@ flash bus on P0.17, P0.13 and P0.14, where revision 2 wires the camera to P0.06, P0.26), the camera supply enable on P1.06 (never driven), the push button (defined on P0.26, wired on P1.01), the LEDs (the firmware's red LED is the white LED on P0.28; the RGB red and blue on P1.14 and P1.13 are not driven), and the `akdreset` node on P1.13, which is -the blue LED. `TBD: firmware alignment with revision 2.` The pin table above is the -hardware; the firmware column will be updated when the firmware is. +the blue LED. The firmware will be aligned with revision 2 before the product ships; until +then the pin table is the hardware and the firmware column describes `main`. --- @@ -340,8 +370,9 @@ JST XH series, 2-pin, 2.5 mm pitch (B2B-XH-A). Pin 1 is VCC_BAT (battery positiv the BQ27427 sense path to the charger), pin 2 is GND. Source: Rev2 netlist and bill of materials. -`TBD: battery connector mating part.` The bill of materials lists a JST-SM pigtail as the -mating cable, which is a different JST series from the XH receptacle on the board. +No battery is supplied with the board. Fit a single-cell rechargeable Li-ion or Li-Po cell +with a JST XH 2-pin plug, positive on pin 1. The charger regulates the cell to 4.2 V and the +board is designed for 3.0 to 4.2 V on VCC_SYS (section 6.2). ### 5.3 J1, camera header @@ -392,12 +423,7 @@ built from. The rows below record what the design sets; every measured value is ### 6.1 Absolute maximum ratings -| Parameter | Value | -|---|---| -| USB VBUS input | `TBD: absolute maximum VBUS` | -| Battery voltage | `TBD: absolute maximum battery voltage` | -| Voltage on any header pin | `TBD: absolute maximum header voltage` | -| Storage temperature | `TBD: storage temperature range` | +`TBD: absolute maximum ratings.` None have been established for the assembly. ### 6.2 Recommended operating conditions @@ -409,7 +435,7 @@ built from. The rows below record what the design sets; every measured value is | VDD_0V8_AKD core rail | | 0.8 | | V | Rev2 schematic | | EXT_VDD_3V3 camera rail | | 3.3 | | V | Rev2 schematic | | Camera header supply | | 3.3 (1.8 option not fitted) | | V | Rev2 netlist | -| Operating temperature | `TBD: operating temperature range` | | | | | +| Operating temperature | `TBD: operating temperature range` | | | °C | Not rated for the assembly. The nRF5340 is rated -40 to 105 °C (Nordic) and the charger -40 to 125 °C junction (TI); the other parts and the cell fitted narrow this | ### 6.3 Current consumption @@ -419,12 +445,15 @@ built from. The rows below record what the design sets; every measured value is | Bluetooth connected, idle | `TBD: idle current` | | Keyword spotting running | `TBD: keyword spotting current` | | Peak during inference | `TBD: peak inference current` | -| Charging current from USB | `TBD: charge current` | +| Charging current from USB | 536 mA nominal fast charge, a design setting (section 3.11); `TBD: measured charge current` | -The firmware can measure the 1.8 V and 0.8 V rails itself through the INA190 amplifiers -(`power read`, `power measure`); the shunt values are 0.1 ohm on the 1.8 V rail and -0.02 ohm on the 0.8 V rail and the fitted amplifier gain is 100 V/V. Source: Rev2 bill of -materials, `src/README.md`. +No board-level consumption has been measured yet. The firmware measures the 1.8 V and +0.8 V rails itself through the INA190 amplifiers (`power read`, `power measure`), which is +the way to fill in the rows for the rails behind them: the shunts are 0.1 ohm on the 1.8 V +rail and 0.02 ohm on the 0.8 V rail, and revision 2 fits the 100 V/V amplifier, so run +`power variant a3` first because the firmware's build-time default is the 25 V/V A1 part. +The total draw, which also covers the charger, the LEDs and the 3.3 V rail, needs a meter in +series with the battery or the USB input. Source: Rev2 bill of materials, `src/README.md`. --- @@ -441,7 +470,8 @@ describe. | Inference | AKD1500 woken through SLEEP for each inference, host SPI at the configured clock, microphone capture running | `src/README.md`, `gpio.c` | | Serial recovery | MCUboot only, listening on the console UART | `src/sysbuild/mcuboot.conf` | -Battery life in each state: `TBD: battery life`. +Battery life in each state depends on the cell fitted; no battery is supplied with the +board and no reference measurement exists yet. `TBD: battery life with a reference cell.` --- @@ -475,7 +505,7 @@ Battery life in each state: `TBD: battery life`. | Mounting holes | None found in the outline data; `TBD: mounting provisions` | Rev2 board outline (DXF) | | USB-C position | Bottom side, centred near one short edge, receptacle projecting beyond the edge | Rev2 placement data | | Microphones | Bottom side, one in each corner beside the USB-C edge | Rev2 placement data | -| Board thickness | `TBD: board thickness` | | +| Board thickness | 1.00 mm, plus or minus 10 % | Rev2 fabrication notes | | Weight | `TBD: weight` | | | Enclosure | `TBD: enclosure dimensions and material` | | @@ -485,7 +515,7 @@ Battery life in each state: `TBD: battery life`. | Item | Value | |---|---| -| Operating temperature | `TBD: operating temperature range` | +| Operating temperature | `TBD: operating temperature range`; not rated for the assembly, see section 6.2 | | Storage temperature | `TBD: storage temperature range` | | Humidity | `TBD: humidity range` | | Regulatory | `TBD: regulatory approvals` | @@ -494,14 +524,14 @@ Battery life in each state: `TBD: battery life`. --- -## 11. Ordering information +## 11. Product information | Item | Value | |---|---| | Product name | AkidaTag | -| Part number | `TBD: orderable part number` | -| What is in the box | `TBD: box contents` | -| Where to order | `TBD: ordering channel` | +| What is in the box | `TBD: box contents`; no battery is included | +| Companion app | BrainChip Connect for Android 13 or later; the [Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect) is open for pre-registration and the app is not yet installable from it | +| Developer resources | [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/), [Developer Hub sign-up](https://developer.brainchip.com/signup/), [BrainChip community on Discord](https://discord.com/invite/9bmd9g52vn) | --- @@ -512,9 +542,9 @@ Battery life in each state: `TBD: battery life`. | Revision | Design | Changes | |---|---|---| | 2 | NRF-AKD1500-002 (V-002), schematic V11, changes dated 2026-07-07, released 2026-08-25 | Test pads added on the ADC inputs; INA190 changed to the gain-100 variant with matching shunts; camera signals brought to a header; LDO added for the camera supply; new level-shifter part for the camera signals; SWD connector added; one RGB LED added; on/off switch added; one user button added | -| 1 | V-001, initial release dated 2025-12-24 | `TBD: revision 1 description` | -Source: the revision summary on the Rev2 schematic cover sheet. +Revision 1 (V-001, dated 2025-12-24) was not released outside BrainChip; revision 2 is the +first board shipped. Source: the revision summary on the Rev2 schematic cover sheet. ### Document @@ -537,8 +567,16 @@ Source: the revision summary on the Rev2 schematic cover sheet. `src/include/fuel_gauge/fuel_gauge.h`, `docs/ble-model-transfer.md`, `docs/firmware-update-over-usb.md`, `AGENTS.md`. - [AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf). -- [Nordic Semiconductor nRF5340 product page](https://www.nordicsemi.com/Products/nRF5340). +- [Nordic Semiconductor nRF5340 product page](https://www.nordicsemi.com/Products/nRF5340) + and [product specification key features](https://docs.nordicsemi.com/bundle/ps_nrf5340/page/keyfeatures_html5.html). +- Texas Instruments BQ25185 datasheet, SLUSF65B: charge-current formula, ILIM/VSET table, + charging thresholds and timers. +- BrainChip AKD1500 application notes AN-001 (interrupt-driven inference), AN-002 (sleep pin + and low-power operation) and AN-003 (clock and frequency management), revision 1.0, + 2026-07-13; the AKD1500 datasheet v1.2 ball descriptions for the strap meanings. +- [BrainChip Connect on Google Play](https://play.google.com/store/apps/details?id=com.brainchip.connect) + for the Android version. --- -TBD: footer +© 2026 BrainChip Holdings Ltd. All rights reserved. diff --git a/docs/hardware/images/akidatag-block-diagram.svg b/docs/hardware/images/akidatag-block-diagram.svg index a80a222..97fa230 100644 --- a/docs/hardware/images/akidatag-block-diagram.svg +++ b/docs/hardware/images/akidatag-block-diagram.svg @@ -1,155 +1,178 @@ - -AkidaTag Rev2 block diagram + +AkidaTag system block diagram, hardware revision 2 - -AkidaTag block diagram (hardware revision 2) - -USB-C receptacle J5 -5 V in, USB 2.0 data - -CP2105 USB to UART -one port used: -console + serial recovery - -SWD header J2 -10-pin 1.27 mm - -2.4 GHz chip antenna -U.FL footprint (not fitted) - -2 x PDM MEMS -microphones -shared clock and data - -ISM330DHCX -6-axis IMU -INT1 to GPIO - -BQ27427 -battery fuel gauge -SOC interrupt to GPIO - -16 MB SPI NOR flash IC1 -firmware update slot -+ LittleFS file system - -Nordic nRF5340 -dual Arm Cortex-M33 -128 MHz application core -64 MHz network core (Bluetooth LE) -1 MB flash, 512 KB RAM - -runs Zephyr / nRF Connect SDK -MCUboot, LittleFS, BLE services - -RGB LED D1 -white LED LED1 -4 GPIO, low side - -Push button SW1 -Power switch SW2 -(slide switch) - -16 MB SPI NOR flash IC2 -model storage on the -AKD1500 SPI master port - -BrainChip AKD1500 -Akida neuromorphic -AI co-processor -SPI slave host interface -25 MHz crystal, PLL -core clock up to 400 MHz -1 MB on-chip memory -0.8 V core, 1.8 V I/O - -Camera header J1 -10-pin 1.27 mm, level-shifted SPI -(2 x SN74AXC2T245), switched 3.3 V - -2 x INA190 current sense -1.8 V rail and 0.8 V rail -into the nRF5340 ADC - -Battery connector J4 -single-cell Li-ion -JST XH, 2-pin - -BQ25185 charger -with power path -STAT1/STAT2 to GPIO - -SW2 -on / off -slide switch - -Regulators -TPS631000 buck-boost 1.8 V (VDD_1V8) -TLV62585 buck 0.8 V, TPS7A2033 LDO 3.3 V - -5 x TPS22991 load switches -AKD 1.8 V, IMU, mics, camera -3.3 V, AKD 0.8 V enable - - -USB 2.0 - - -UART0, 115200 8N1 - - -SWD - - -ANT - - -PDM - - - -I2C1, 400 kHz - - -SPIM3, CS1 - - - - -SPIM4 host SPI - -8 MHz default, up to 32 MHz - -CS0 AKD1500, CS1 flash - - -SLEEP, PWR_GOOD - -GPIO0..3, async IRQ - - -SPI master, quad - - -SPI + enable - - -SAADC - - -VBUS 5 V - - - -SYS - - -VCC_SYS - - - -power enables (5 GPIO) + +AkidaTag system block diagram (hardware revision 2) + +POWER SYSTEM + +USB & DEBUG + +COMPUTE & MEMORY + +RF FRONT-END + +SENSORS + +EXPANSION + +INDICATORS & CONTROLS + +USB-C J5 +5 V VBUS + +Battery J4 +single-cell Li-ion + +Battery circuit +BQ25185 charger with power path +BQ27427 fuel gauge (I2C) + +On/off switch +SW2 (slide) + +Power rails +TPS631000 1.8 V, TLV62585 0.8 V, TPS7A2033 3.3 V +5 x TPS22991 load switches, 2 x INA190 current sense + + + + +SYS + + +VCC_SYS 3.0 to 4.2 V + + +rails + +USB-C J5 +D+ / D- + +CP2105 +USB-UART bridge + +SWD header J2 +10-pin 1.27 mm + + + +UART0 + + +SWD + +nRF5340 +dual-core Arm Cortex-M33 +128 MHz application core +64 MHz network core +Bluetooth Low Energy +1 MB flash, 512 KB RAM + +Zephyr, MCUboot, LittleFS + +AKD1500 +Akida neuromorphic +AI co-processor +SPI slave host interface +25 MHz crystal, PLL +core clock up to 400 MHz +1 MB on-chip memory +0.8 V core, 1.8 V I/O + +SPI NOR flash IC1 +16 MB, host +update slot + LittleFS + +SPI NOR flash IC2 +16 MB, AI +model storage + + +SPIM4 SPI + +8 to 32 MHz + + +SLEEP, PWR_GOOD + +GPIO0..3 (IRQ) + + +SPIM3 + + +SPI master, quad + + +CS1 + +feed-through: the host reaches IC2 through the AKD1500 + +on SPIM4 chip select 1 + +Both flashes are 128 Mbit SPI NOR; + +IC1 single-lane from the host, IC2 quad from the AKD1500 + +Firmware update slot, LittleFS records and the AKD1500 model + +program all live in external flash; the nRF5340 boots from internal flash + +RF matching +network + +Chip antenna +2.4 GHz +(U.FL footprint, not fitted) + + + +ANT + +6-axis IMU: ISM330DHCX +accelerometer + gyroscope, INT1 + +PDM microphone 1 (U19) +digital MEMS, channel A + +PDM microphone 2 (U20) +digital MEMS, channel B + + +I2C1, 400 kHz + + + +PDM clock + data + +Camera header J1 +10-pin 1.27 mm, level-shifted SPI +switched 3.3 V supply + + +SPI + enables + +RGB LED D1 +white LED LED1 +4 GPIO + +User button SW1 +GPIO P1.01 +(on/off switch: SW2) + + + +GPIO + +Power enables from the nRF5340: P0.19 (AKD1500 1.8 V), P0.20 (IMU), P0.21 (microphones), P0.22 (AKD1500 0.8 V), P1.06 (camera header) + +Current sense outputs into the nRF5340 ADC: AIN0 (1.8 V rail), AIN1 (0.8 V rail) + +Drawn from the revision 2 netlist and bill of materials. Changes from the earlier board: camera header instead of a 20-pin expansion connector, + +one button and an on/off switch instead of three buttons, a 10-pin SWD header, on-board current sensing, and the U.FL connector left unfitted. diff --git a/docs/hardware/technical-specifications.md b/docs/hardware/technical-specifications.md index 4b6786e..8847601 100644 --- a/docs/hardware/technical-specifications.md +++ b/docs/hardware/technical-specifications.md @@ -1,12 +1,16 @@ # AkidaTag technical specifications -AkidaTag is a compact, battery-powered edge-AI device that runs neural networks on the -BrainChip AKD1500 Akida neuromorphic processor, listens through on-board microphones, -senses motion, and talks to the BrainChip Connect app over Bluetooth Low Energy. It learns -new keywords on the device itself, with no cloud connection. +AkidaTag is a compact, battery-powered edge-AI device built on BrainChip's Akida™ +neuromorphic processing engine. It runs neural networks on the AKD1500 AI co-processor, +listens through two on-board microphones, senses motion, and talks to the BrainChip +Connect app over Bluetooth Low Energy. Models are built with BrainChip's MetaTF™ flow and +loaded from the app, and the device learns new keywords on-device, with no cloud +connection. AkidaTag is made for developers who want to evaluate event-based AI on a +wearable-sized, always-on device. This page is the buyer-facing summary. The engineering reference, with pinouts, the power -tree and the full connector detail, is the [datasheet](datasheet.md). +tree and the full connector detail, is the [datasheet](datasheet.md); the system view is +the [block diagram](block-diagram.md). | Document status | | |---|---| @@ -16,126 +20,96 @@ tree and the full connector detail, is the [datasheet](datasheet.md). --- -## At a glance +## Key features -| | | -|---|---| -| AI processor | BrainChip AKD1500 Akida neuromorphic co-processor with on-device learning | -| Host processor | Nordic nRF5340, dual Arm Cortex-M33, 128 MHz | -| Wireless | Bluetooth Low Energy, on-board antenna | -| Sensors | Two MEMS microphones, six-axis accelerometer and gyroscope | -| Expansion | SPI camera header | -| Power | Rechargeable single-cell Li-ion, USB-C charging, on/off switch | -| Size | 27.7 mm x 39.5 mm board | -| Companion app | BrainChip Connect | - ---- - -## Processing - -| Item | Specification | -|---|---| -| AI co-processor | BrainChip AKD1500, Akida neuron fabric, event-based neuromorphic architecture, 22 nm FD-SOI, 7 mm x 7 mm package | -| AI memory | 1 MB on-chip | -| AI clock | Up to 400 MHz core clock from an on-board 25 MHz crystal; 400 MHz default in firmware | -| On-device learning | Yes; the firmware exposes keyword learning over Bluetooth | -| Host interface to the AI processor | SPI at 8 MHz by default, up to 32 MHz | -| Host processor | Nordic nRF5340: 128 MHz Arm Cortex-M33 application core with 1 MB flash and 512 KB RAM, plus a 64 MHz Arm Cortex-M33 network core for Bluetooth | -| Operating system | Zephyr RTOS, nRF Connect SDK, MCUboot bootloader | - -## Memory - -| Item | Specification | -|---|---| -| Model storage | 16 MB SPI NOR flash dedicated to the AI processor | -| Firmware storage | 16 MB SPI NOR flash for firmware updates and a LittleFS file system, in addition to the host's 1 MB internal flash | - -## Sensors - -| Item | Specification | -|---|---| -| Microphones | Two digital PDM MEMS microphones; the firmware captures audio at 16 kHz, 16-bit | -| Motion | STMicroelectronics ISM330DHCX six-axis accelerometer and gyroscope; firmware defaults 208 Hz, plus or minus 8 g and plus or minus 500 degrees per second | -| Camera | SPI camera header (10-pin, 1.27 mm pitch) with switched 3.3 V supply; the firmware supports an ArduCam Mega camera at 96 x 96 and 128 x 128 pixels | -| Battery monitoring | Fuel gauge reporting state of charge to the app; charger status reporting | -| Power monitoring | On-board current sensing of the 1.8 V system rail and the 0.8 V AI core rail, readable from the firmware console | - -## Connectivity - -| Item | Specification | -|---|---| -| Bluetooth | Bluetooth Low Energy peripheral, device name `AkidaTag`; LE Secure Connections only with bonding; firmware update over Bluetooth | -| Antenna | On-board 2.4 GHz chip antenna | -| Range | `TBD: Bluetooth range` | -| USB | USB-C: 5 V charging input and a USB-to-serial console at 115200 baud; firmware update over the cable with no tools other than a computer | -| Debug | 10-pin 1.27 mm SWD header | - -## Power - -| Item | Specification | -|---|---| -| Battery | Single-cell rechargeable Li-ion, 3.0 to 4.2 V, on a JST XH 2-pin connector | -| Battery capacity | `TBD: battery capacity` | -| Battery life | `TBD: battery life` | -| Charging | On-board linear charger with power path; charges from USB-C 5 V while the device runs | -| Charge time | `TBD: charge time` | -| Power switch | On/off slide switch | -| Power consumption | `TBD: power consumption by mode` | +- BrainChip AKD1500 Akida neuromorphic AI co-processor with on-device learning +- Nordic nRF5340 dual-core Arm Cortex-M33 host with Bluetooth Low Energy +- 16 MB of model storage for the AI processor and 16 MB of firmware and file storage + for the host +- Two digital MEMS microphones for always-on audio +- Six-axis accelerometer and gyroscope +- SPI camera header for vision experiments +- Single-cell Li-ion battery support with USB-C charging, fuel gauge and on/off switch +- On-board current sensing of the AI and system rails for power measurements +- Firmware update over Bluetooth or over the USB-C cable +- Companion BrainChip Connect app to load models, run the demonstrations and start + on-device learning -## Indicators and controls +## Applications -| Item | Specification | -|---|---| -| LEDs | One RGB LED and one white LED under firmware control | -| Buttons | One push button; the on/off slide switch | - -## Physical +- Keyword spotting and voice control with on-device personalisation +- Vibration and motion classification, anomaly detection +- Low-power vision with an attached SPI camera +- Evaluation of Akida event-based inference on a battery-powered device -| Item | Specification | -|---|---| -| Board dimensions | 27.7 mm x 39.5 mm, six-layer PCB, chamfered corners | -| Enclosure | `TBD: enclosure dimensions, material and colour` | -| Weight | `TBD: weight` | -| Mounting | `TBD: mounting provisions` | +--- -## Operating environment +## Specifications -| Item | Specification | +| | | |---|---| -| Operating temperature | `TBD: operating temperature range` | -| Storage temperature | `TBD: storage temperature range` | -| Humidity | `TBD: humidity range` | -| Ingress protection | `TBD: ingress protection rating` | +| **AI co-processor** | BrainChip AKD1500: Akida neuron fabric, event-based neuromorphic architecture, 22 nm FD-SOI, 7 mm x 7 mm package | +| **AI on-chip memory** | 1 MB | +| **AI clock** | Up to 400 MHz core clock from an on-board 25 MHz crystal; 400 MHz default in firmware | +| **On-device learning** | Yes; keyword learning exposed over Bluetooth | +| **Host to AI interface** | SPI, 8 MHz by default, up to 32 MHz | +| **Host processor** | Nordic nRF5340: 128 MHz Arm Cortex-M33 application core with 1 MB flash and 512 KB RAM, plus a 64 MHz Arm Cortex-M33 network core for Bluetooth | +| **Operating system** | Zephyr RTOS on the nRF Connect SDK, MCUboot bootloader | +| **Model storage** | 16 MB SPI NOR flash dedicated to the AI processor | +| **Firmware storage** | 16 MB SPI NOR flash for firmware updates and a LittleFS file system, in addition to the host's 1 MB internal flash | +| **Microphones** | Two digital PDM MEMS microphones; the firmware captures audio at 16 kHz, 16-bit, and the keyword spotting demonstration uses one of the two | +| **Motion sensor** | STMicroelectronics ISM330DHCX six-axis accelerometer and gyroscope; firmware defaults 208 Hz, plus or minus 8 g and plus or minus 500 degrees per second | +| **Camera** | SPI camera header (10-pin, 1.27 mm pitch) with switched 3.3 V supply; the firmware supports an ArduCam Mega camera at 96 x 96 and 128 x 128 pixels | +| **Battery monitoring** | Fuel gauge reporting state of charge to the app; charger status reporting | +| **Power monitoring** | On-board current sensing of the 1.8 V system rail and the 0.8 V AI core rail, readable from the firmware console | +| **Bluetooth** | Bluetooth Low Energy peripheral, device name `AkidaTag`; LE Secure Connections only with bonding; firmware update over Bluetooth | +| **Radio** | nRF5340 radio, specified by Nordic for -40 to +3 dBm configurable transmit power and -98 dBm sensitivity at 1 Mbps; on-board 2.4 GHz chip antenna | +| **Bluetooth range** | `TBD: Bluetooth range` | +| **USB** | USB-C: 5 V charging input and a USB-to-serial console at 115200 baud; firmware update over the cable with nothing but a computer | +| **Debug** | 10-pin 1.27 mm SWD header | +| **Battery** | Not included. Fits a single-cell rechargeable Li-ion or Li-Po cell, 3.0 to 4.2 V, on a JST XH 2-pin connector | +| **Battery life** | Depends on the cell fitted; `TBD: battery life with a reference cell` | +| **Charging** | On-board linear charger with power path, 536 mA nominal fast charge from USB-C 5 V; the device runs while charging; charge time depends on the cell fitted | +| **Power switch** | On/off slide switch | +| **Power consumption** | `TBD: power consumption by mode` | +| **Indicators** | One RGB LED and one white LED under firmware control | +| **Controls** | One user button; the on/off slide switch | +| **Board dimensions** | 27.7 mm x 39.5 mm, 1.0 mm thick, six-layer PCB, chamfered corners | +| **Enclosure** | `TBD: enclosure dimensions, material and colour` | +| **Weight** | `TBD: weight` | +| **Operating temperature** | `TBD: operating temperature range`; the board as a whole has not been rated, and the host processor is rated -40 to 105 °C | +| **Storage temperature** | `TBD: storage temperature range` | +| **Humidity** | `TBD: humidity range` | +| **Ingress protection** | `TBD: ingress protection rating` | +| **Regulatory** | `TBD: regulatory approvals` | +| **Bluetooth qualification** | `TBD: Bluetooth qualification` | +| **RoHS** | `TBD: RoHS statement` | +| **What is in the box** | `TBD: box contents`; no battery is included | -## Software and compatibility +--- -| Item | Specification | -|---|---| -| Companion app | BrainChip Connect: connects over Bluetooth, loads models onto the device, runs the demonstrations and starts on-device learning | -| Supported phones | `TBD: supported mobile platforms and versions` | -| Firmware | Firmware from this repository; updates over Bluetooth (MCUmgr) or over USB-C from a computer | -| Model tooling | Models built with BrainChip MetaTF from TensorFlow/Keras or PyTorch, then packaged with the model workflow in this repository and sent to the device by the app | -| Demonstrations included | Keyword spotting with on-device edge learning; motion sensing; camera capture from the console | +## Software -## Compliance +Models for AkidaTag are built with BrainChip's MetaTF flow from TensorFlow/Keras or +PyTorch, packaged with the model workflow in this repository, and sent to the device by +the BrainChip Connect app over Bluetooth. The firmware in this repository runs the +demonstrations: keyword spotting with on-device edge learning, motion sensing, and camera +capture from the console. Firmware updates arrive over Bluetooth (MCUmgr) or over the +USB-C cable from a computer. -| Item | Specification | +| | | |---|---| -| Regulatory | `TBD: regulatory approvals` | -| Bluetooth qualification | `TBD: Bluetooth qualification` | -| RoHS | `TBD: RoHS statement` | +| **Companion app** | BrainChip Connect for Android 13 or later. The Google Play listing is open for pre-registration; the app is not yet installable from it. `TBD: iOS availability` | +| **Firmware** | This repository, open for building and modification | +| **Demonstrations** | Keyword spotting with on-device edge learning; motion sensing; camera capture | -## What is in the box +## Resources -`TBD: box contents` - -## Ordering - -| Item | Specification | -|---|---| -| Product name | AkidaTag | -| Part number | `TBD: orderable part number` | -| Where to order | `TBD: ordering channel` | +- [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/) +- [Developer Hub sign-up](https://developer.brainchip.com/signup/) +- [BrainChip Connect on Google Play (pre-registration)](https://play.google.com/store/apps/details?id=com.brainchip.connect) +- [BrainChip community on Discord](https://discord.com/invite/9bmd9g52vn) +- [AKD1500 product brief](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf) --- @@ -143,10 +117,12 @@ tree and the full connector detail, is the [datasheet](datasheet.md). Every value on this page is taken from the AkidaTag revision 2 design files, the AkidaTag firmware 1.2.0+0 in this repository, the -[AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf) -or the [Nordic nRF5340 product page](https://www.nordicsemi.com/Products/nRF5340). The -[datasheet](datasheet.md) lists the source next to each value. +[AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf), +the [Nordic nRF5340 product specification](https://docs.nordicsemi.com/bundle/ps_nrf5340/page/keyfeatures_html5.html), +the Texas Instruments BQ25185 datasheet or the +[Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect). +The [datasheet](datasheet.md) lists the source next to each value. --- -TBD: footer +© 2026 BrainChip Holdings Ltd. All rights reserved. From e412727420197168b210620a60254586c6987608 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Fri, 25 Sep 2026 23:55:49 -0700 Subject: [PATCH 3/7] docs(hardware): cite the board test records and drop the alignment claim No source says the firmware will be aligned with revision 2 before the product ships, so the datasheet now only states the differences. The post-fabrication test report, the testing checklist, the SWD connection guide and the INA190 datasheet are cited for what they settle: no current measurement exists yet, the SWD guide covers the earlier board's pads, and the amplifier's offset and gain bound what the on-board current measurement can resolve. --- docs/hardware/datasheet.md | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index 9c60e89..b2cc333 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -146,8 +146,7 @@ The firmware's partition map uses the first 8 MB of IC1. Source: `src/pm_static. Both positions are fitted with the Winbond W25Q128JWPIQ (1.8 V, 128 Mbit) listed in the Rev2 bill of materials. The firmware on `main` still identifies the devices by the JEDEC ID -of the Micron part named in the schematic symbols; it will be aligned with the Winbond part -before the product ships. +of the Micron part named in the schematic symbols, so it does not match the fitted part. ### 3.4 Audio: microphones @@ -228,7 +227,10 @@ header is VDD_1V8. Pin 6 carries nRESET and pin 10 is not connected. That differs from the Arm 10-pin Cortex Debug layout, which puts SWO on pin 6 and nRESET on pin 10, so a probe's reset line does not -reach the board through a pin-to-pin cable. `TBD: J2 pinout verified on a board.` +reach the board through a pin-to-pin cable. `TBD: J2 pinout verified on a board.` The SWD +connection guide of April 2026 describes the earlier board's labelled debug pads (GND, SWD, +CLK, NRST and a 1.8 V reference) wired to a J-Link with five flying leads, not this header, +so it does not settle the question. ### 3.10 Indicators and controls @@ -351,8 +353,8 @@ flash bus on P0.17, P0.13 and P0.14, where revision 2 wires the camera to P0.06, P0.26), the camera supply enable on P1.06 (never driven), the push button (defined on P0.26, wired on P1.01), the LEDs (the firmware's red LED is the white LED on P0.28; the RGB red and blue on P1.14 and P1.13 are not driven), and the `akdreset` node on P1.13, which is -the blue LED. The firmware will be aligned with revision 2 before the product ships; until -then the pin table is the hardware and the firmware column describes `main`. +the blue LED. The pin table is the hardware; the firmware column describes `main` as it is +today. --- @@ -454,6 +456,17 @@ rail and 0.02 ohm on the 0.8 V rail, and revision 2 fits the 100 V/V amplifier, `power variant a3` first because the firmware's build-time default is the 25 V/V A1 part. The total draw, which also covers the charger, the LEDs and the 3.3 V rail, needs a meter in series with the battery or the USB input. Source: Rev2 bill of materials, `src/README.md`. +The only board test records available, the post-fabrication PCB test report of March 2026 +and the PCB testing checklist of February 2026, cover bare-board impedance and short/open +checks and the power-on procedure, and contain no current measurements. + +What the on-board measurement can resolve follows from the INA190 datasheet. The A3 device +has a gain error of plus or minus 0.3 % and a zero-current output offset of up to 3 mV at a +1.8 V supply, which corresponds to 0.3 mA on the 1.8 V rail and 1.5 mA on the 0.8 V rail. +With the firmware's ADC setting of gain 1/3 against the internal 0.6 V reference, full scale +is 1.8 V at the amplifier output, or 180 mA on the 1.8 V rail and 900 mA on the 0.8 V rail, +less the amplifier's 20 mV swing limit below its supply. Source: INA190 datasheet SBOS863D; +`src/core/interface/current_ic/current_ic.c`. --- @@ -571,6 +584,11 @@ first board shipped. Source: the revision summary on the Rev2 schematic cover sh and [product specification key features](https://docs.nordicsemi.com/bundle/ps_nrf5340/page/keyfeatures_html5.html). - Texas Instruments BQ25185 datasheet, SLUSF65B: charge-current formula, ILIM/VSET table, charging thresholds and timers. +- Texas Instruments INA190 datasheet, SBOS863D: gain options, gain error, zero-current + output offset and output swing. +- Board test records, internal: post-fabrication PCB test report (version 1.0, 2026-03-13), + PCB testing checklist and procedures (version 1.0, 2026-02-18) and Spark board SWD + connection guide (version 1.1, 2026-04-10); read for facts only, nothing copied. - BrainChip AKD1500 application notes AN-001 (interrupt-driven inference), AN-002 (sleep pin and low-power operation) and AN-003 (clock and frequency management), revision 1.0, 2026-07-13; the AKD1500 datasheet v1.2 ball descriptions for the strap meanings. From 9d3d421e2b5c8801b43d46b507cbd5ea314601d8 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Sat, 26 Sep 2026 19:20:39 -0700 Subject: [PATCH 4/7] docs(hardware): apply the answers on the remaining values The board ships in its enclosure with no battery, cable or camera; the iOS app is to follow the Android pre-registration; the SWD header is documented as the schematic wires it; the fuel gauge sense orientation on revision 2 matches the BQ27427 datasheet, which the firmware's sign correction does not expect; the compliance rows are removed until a certification exists; and the battery-life placeholder goes because it depends on the cell fitted. The AKD1500 application notes are no longer named as sources. --- docs/hardware/block-diagram.md | 9 +++-- docs/hardware/datasheet.md | 49 ++++++++++------------- docs/hardware/technical-specifications.md | 19 ++++----- 3 files changed, 35 insertions(+), 42 deletions(-) diff --git a/docs/hardware/block-diagram.md b/docs/hardware/block-diagram.md index 6bd5d55..3ea54cf 100644 --- a/docs/hardware/block-diagram.md +++ b/docs/hardware/block-diagram.md @@ -72,7 +72,8 @@ firmware drives the enable high. | CAM_PWR_EN | P1.06 | U2 | VDD_3V3_1V8_CAM | The battery sits behind the BQ27427 fuel gauge: the charger's BAT pin reaches the gauge's -sense input, and the gauge's BAT pin reaches the connector. The gauge is on I2C1 at +SRX sense input, and the gauge's BAT pin reaches the connector, which is the orientation the +BQ27427 datasheet specifies. The gauge is on I2C1 at address 0x55 and raises its GPOUT interrupt line to P0.30 when the state of charge changes. The charger's STAT1 and STAT2 outputs go to P0.23 and P0.24 with pull-ups; a 10 kilohm NTC thermistor is on the charger's TS pin and a second on the gauge's BIN pin. @@ -244,9 +245,9 @@ Both amplifiers run from VDD_1V8 with their enable pins tied high. The A3 gain o The revision 2 schematic (SI-NRF-AKD_BRD-002 V11, 2026-08-25), netlist report, bill of materials and board outline; the earlier system block diagram and labelled layout -drawing (January 2026); the Texas Instruments INA190 datasheet (SBOS863D); the AKD1500 -datasheet v1.2 ball descriptions and BrainChip application note AN-003 for the strap -meanings; and the firmware board overlay `src/boards/nrf5340_cpuapp_akidatag.overlay`, +drawing (January 2026); the Texas Instruments INA190 datasheet (SBOS863D) and BQ27427 +datasheet (SLUSEB5B); BrainChip AKD1500 documentation for the strap meanings; and the +firmware board overlay `src/boards/nrf5340_cpuapp_akidatag.overlay`, `src/core/interface/gpio/gpio.c`, `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp` and `src/README.md` on `main` at firmware 1.2.0+0. diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index b2cc333..c82eeaf 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -109,24 +109,22 @@ back. The chip can learn new classes on the device. | Core clock in firmware | 400 MHz default from the internal 800 MHz PLL; 5 to 400 MHz selectable | `src/Kconfig`, `src/README.md`; product brief gives the 5 to 400 MHz range | | Host SPI clock in firmware | 8 MHz default, runtime selectable 1 to 32 MHz | `src/Kconfig`, `src/README.md` | | Supplies | 0.8 V core (VDD_0V8_AKD), 1.8 V I/O (VDD_1V8_AKD); PLL supplies through ferrite beads from the same rails; PCIe PHY supplies tied to ground | Rev2 netlist | -| Strapping | PCIe host select low (SPI host); SEL_CLK low (crystal oscillator); SPI slave mode pins low; OP_MODE0 low (crystal as the clock source); OP_MODE1 high (Safe Mode, see below); TAP_SEL and TESTMODE low | Rev2 netlist; AKD1500 datasheet v1.2 ball descriptions | +| Strapping | PCIe host select low (SPI host); SEL_CLK low (crystal oscillator); SPI slave mode pins low; OP_MODE0 low (crystal as the clock source); OP_MODE1 high (Safe Mode, see below); TAP_SEL and TESTMODE low | Rev2 netlist; BrainChip AKD1500 documentation for the strap meanings | | Host control lines | SLEEP from P1.07; PWR_GOOD from P1.05 (pulled up on the board); GPIO0..GPIO3 to P1.11, P1.12, P0.02, P0.03 | Rev2 netlist | | Reset | No host-driven reset line is wired; PCIE_PERST_N is left unconnected | Rev2 netlist | Between inferences the firmware asserts SLEEP, which gates the AKD1500 clocks while the loaded model is retained, and releases it on demand with a reference count. The `app stop` command additionally turns the AKD1500 PLL off for the lowest idle power. -GPIO3 (P0.03) is the completion interrupt the firmware waits on after each inference, which -is the pad BrainChip's application note AN-001 recommends for it. The sleep behaviour is -described in AN-002. +GPIO3 (P0.03) is the completion interrupt the firmware waits on after each inference. OP_MODE1 is strapped high, which puts the AKD1500 in Safe Mode: after reset it stays on the 25 MHz reference clock instead of switching itself onto its PLL, and the host has to make that switch once the PLL reports lock. The firmware does this at a low host SPI clock and only then raises the clock, because the AKD1500 requires the host clock to stay at or below a quarter of its SPI slave core clock, which caps the host at a few megahertz while the -reference clock is in use. Source: `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp`; -AKD1500 application note AN-003. +reference clock is in use. Source: `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp`, +which documents the mode and performs the switch. ### 3.3 Memory @@ -225,12 +223,9 @@ J2 is a 10-pin, 1.27 mm pitch header carrying SWDIO, SWDCLK and reset, with ESD on all three lines. Its pinout is in section 5.4. The board's reference voltage on this header is VDD_1V8. -Pin 6 carries nRESET and pin 10 is not connected. That differs from the Arm 10-pin Cortex -Debug layout, which puts SWO on pin 6 and nRESET on pin 10, so a probe's reset line does not -reach the board through a pin-to-pin cable. `TBD: J2 pinout verified on a board.` The SWD -connection guide of April 2026 describes the earlier board's labelled debug pads (GND, SWD, -CLK, NRST and a 1.8 V reference) wired to a J-Link with five flying leads, not this header, -so it does not settle the question. +Pin 6 carries nRESET and pin 10 is not connected, as the revision 2 schematic wires it. That +differs from the Arm 10-pin Cortex Debug layout, which puts SWO on pin 6 and nRESET on +pin 10, so a probe's reset line does not reach the board through a pin-to-pin cable. ### 3.10 Indicators and controls @@ -277,10 +272,12 @@ the IMU, then the microphones, then the camera enable. Source: No battery is supplied with the board. The firmware programs the fuel gauge for an 1100 mAh, 4.2 V cell with a 3000 mV terminate voltage and a 4150 mV taper voltage, and the source notes that these values are for a test battery, so the state of charge it reports is -only as good as the match between those parameters and the cell fitted. The firmware also -inverts the sign of the gauge's current reading to correct for a sense resistor that the -code describes as physically reversed; the netlist alone cannot show whether revision 2 -still has that orientation. `TBD: fuel gauge sense orientation on revision 2.` Source: +only as good as the match between those parameters and the cell fitted. Revision 2 +connects the battery to the gauge's BAT pin and the charger to its SRX pin, which is the +orientation the BQ27427 datasheet specifies for its integrated sense resistor. The firmware +on `main` still inverts the sign of the gauge's current reading to correct for a sense +resistor that its code describes as physically reversed, a correction that inverts the sign +on this orientation. Source: Rev2 netlist; BQ27427 datasheet SLUSEB5B, pin functions; `src/include/fuel_gauge/fuel_gauge.h`, `src/core/interface/fuel_gauge/fuel_gauge.c`. --- @@ -484,7 +481,7 @@ describe. | Serial recovery | MCUboot only, listening on the console UART | `src/sysbuild/mcuboot.conf` | Battery life in each state depends on the cell fitted; no battery is supplied with the -board and no reference measurement exists yet. `TBD: battery life with a reference cell.` +board. --- @@ -520,20 +517,17 @@ board and no reference measurement exists yet. `TBD: battery life with a referen | Microphones | Bottom side, one in each corner beside the USB-C edge | Rev2 placement data | | Board thickness | 1.00 mm, plus or minus 10 % | Rev2 fabrication notes | | Weight | `TBD: weight` | | -| Enclosure | `TBD: enclosure dimensions and material` | | +| Enclosure | The board ships in its enclosure; `TBD: enclosure dimensions and material` | BrainChip product decision | --- -## 10. Environmental and compliance +## 10. Environmental | Item | Value | |---|---| | Operating temperature | `TBD: operating temperature range`; not rated for the assembly, see section 6.2 | | Storage temperature | `TBD: storage temperature range` | | Humidity | `TBD: humidity range` | -| Regulatory | `TBD: regulatory approvals` | -| Bluetooth qualification | `TBD: Bluetooth qualification` | -| RoHS | The Rev2 bill of materials marks every listed part RoHS compliant except the nRF5340 line, which is blank; `TBD: board-level RoHS statement` | --- @@ -542,8 +536,8 @@ board and no reference measurement exists yet. `TBD: battery life with a referen | Item | Value | |---|---| | Product name | AkidaTag | -| What is in the box | `TBD: box contents`; no battery is included | -| Companion app | BrainChip Connect for Android 13 or later; the [Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect) is open for pre-registration and the app is not yet installable from it | +| What is in the box | The AkidaTag board in its enclosure. No battery, USB-C cable or camera is included | +| Companion app | BrainChip Connect for Android 13 or later; the [Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect) is open for pre-registration and the app is not yet installable from it. An iOS version is to follow on the App Store | | Developer resources | [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/), [Developer Hub sign-up](https://developer.brainchip.com/signup/), [BrainChip community on Discord](https://discord.com/invite/9bmd9g52vn) | --- @@ -589,9 +583,10 @@ first board shipped. Source: the revision summary on the Rev2 schematic cover sh - Board test records, internal: post-fabrication PCB test report (version 1.0, 2026-03-13), PCB testing checklist and procedures (version 1.0, 2026-02-18) and Spark board SWD connection guide (version 1.1, 2026-04-10); read for facts only, nothing copied. -- BrainChip AKD1500 application notes AN-001 (interrupt-driven inference), AN-002 (sleep pin - and low-power operation) and AN-003 (clock and frequency management), revision 1.0, - 2026-07-13; the AKD1500 datasheet v1.2 ball descriptions for the strap meanings. +- BrainChip AKD1500 documentation for the strap meanings and the Safe Mode clock behaviour. +- Texas Instruments BQ27427 datasheet, SLUSEB5B: pin functions. +- BrainChip product decisions of September 2026: the enclosure ships with the board, the box + contents, and the companion app platforms. - [BrainChip Connect on Google Play](https://play.google.com/store/apps/details?id=com.brainchip.connect) for the Android version. diff --git a/docs/hardware/technical-specifications.md b/docs/hardware/technical-specifications.md index 8847601..6e63ad9 100644 --- a/docs/hardware/technical-specifications.md +++ b/docs/hardware/technical-specifications.md @@ -68,23 +68,19 @@ the [block diagram](block-diagram.md). | **USB** | USB-C: 5 V charging input and a USB-to-serial console at 115200 baud; firmware update over the cable with nothing but a computer | | **Debug** | 10-pin 1.27 mm SWD header | | **Battery** | Not included. Fits a single-cell rechargeable Li-ion or Li-Po cell, 3.0 to 4.2 V, on a JST XH 2-pin connector | -| **Battery life** | Depends on the cell fitted; `TBD: battery life with a reference cell` | +| **Battery life** | Depends on the cell fitted | | **Charging** | On-board linear charger with power path, 536 mA nominal fast charge from USB-C 5 V; the device runs while charging; charge time depends on the cell fitted | | **Power switch** | On/off slide switch | | **Power consumption** | `TBD: power consumption by mode` | | **Indicators** | One RGB LED and one white LED under firmware control | | **Controls** | One user button; the on/off slide switch | | **Board dimensions** | 27.7 mm x 39.5 mm, 1.0 mm thick, six-layer PCB, chamfered corners | -| **Enclosure** | `TBD: enclosure dimensions, material and colour` | +| **Enclosure** | Ships in its enclosure; `TBD: enclosure dimensions, material and colour` | | **Weight** | `TBD: weight` | | **Operating temperature** | `TBD: operating temperature range`; the board as a whole has not been rated, and the host processor is rated -40 to 105 °C | | **Storage temperature** | `TBD: storage temperature range` | | **Humidity** | `TBD: humidity range` | -| **Ingress protection** | `TBD: ingress protection rating` | -| **Regulatory** | `TBD: regulatory approvals` | -| **Bluetooth qualification** | `TBD: Bluetooth qualification` | -| **RoHS** | `TBD: RoHS statement` | -| **What is in the box** | `TBD: box contents`; no battery is included | +| **What is in the box** | The AkidaTag board in its enclosure. No battery, USB-C cable or camera is included | --- @@ -99,7 +95,7 @@ USB-C cable from a computer. | | | |---|---| -| **Companion app** | BrainChip Connect for Android 13 or later. The Google Play listing is open for pre-registration; the app is not yet installable from it. `TBD: iOS availability` | +| **Companion app** | BrainChip Connect for Android 13 or later. The Google Play listing is open for pre-registration; the app is not yet installable from it. An iOS version is to follow on the App Store | | **Firmware** | This repository, open for building and modification | | **Demonstrations** | Keyword spotting with on-device edge learning; motion sensing; camera capture | @@ -119,9 +115,10 @@ Every value on this page is taken from the AkidaTag revision 2 design files, the firmware 1.2.0+0 in this repository, the [AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf), the [Nordic nRF5340 product specification](https://docs.nordicsemi.com/bundle/ps_nrf5340/page/keyfeatures_html5.html), -the Texas Instruments BQ25185 datasheet or the -[Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect). -The [datasheet](datasheet.md) lists the source next to each value. +the Texas Instruments BQ25185 datasheet, the +[Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect) +or BrainChip's product decisions of September 2026 on the enclosure, the box contents and +the app platforms. The [datasheet](datasheet.md) lists the source next to each value. --- From 6861e6e0df3165c54ea679975607ab9a1a1fa872 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Sat, 26 Sep 2026 19:24:30 -0700 Subject: [PATCH 5/7] docs(hardware): defer the consumption figures to a later revision --- docs/hardware/datasheet.md | 12 +++++------- docs/hardware/technical-specifications.md | 2 +- 2 files changed, 6 insertions(+), 8 deletions(-) diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index c82eeaf..de0191d 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -438,13 +438,11 @@ built from. The rows below record what the design sets; every measured value is ### 6.3 Current consumption -| Condition | Value | -|---|---| -| Sleep, Bluetooth advertising | `TBD: sleep current` | -| Bluetooth connected, idle | `TBD: idle current` | -| Keyword spotting running | `TBD: keyword spotting current` | -| Peak during inference | `TBD: peak inference current` | -| Charging current from USB | 536 mA nominal fast charge, a design setting (section 3.11); `TBD: measured charge current` | +Current consumption per state (asleep and advertising, connected and idle, keyword +spotting running, peak during an inference) and the charge current drawn from USB will be +measured on a revision 2 board and added in a later revision of this datasheet. +`TBD: current consumption, deferred to a later revision.` Until then the only current +figure on this page is the charger's 536 mA nominal fast-charge setting in section 3.11. No board-level consumption has been measured yet. The firmware measures the 1.8 V and 0.8 V rails itself through the INA190 amplifiers (`power read`, `power measure`), which is diff --git a/docs/hardware/technical-specifications.md b/docs/hardware/technical-specifications.md index 6e63ad9..a3d342c 100644 --- a/docs/hardware/technical-specifications.md +++ b/docs/hardware/technical-specifications.md @@ -71,7 +71,7 @@ the [block diagram](block-diagram.md). | **Battery life** | Depends on the cell fitted | | **Charging** | On-board linear charger with power path, 536 mA nominal fast charge from USB-C 5 V; the device runs while charging; charge time depends on the cell fitted | | **Power switch** | On/off slide switch | -| **Power consumption** | `TBD: power consumption by mode` | +| **Power consumption** | `TBD: power consumption, to be measured for a later revision` | | **Indicators** | One RGB LED and one white LED under firmware control | | **Controls** | One user button; the on/off slide switch | | **Board dimensions** | 27.7 mm x 39.5 mm, 1.0 mm thick, six-layer PCB, chamfered corners | From 7ed7964e36bf2a80707b68687aa39a91ec1a7398 Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Sun, 27 Sep 2026 01:49:38 -0700 Subject: [PATCH 6/7] docs(hardware): keep only short block names inside the figures The system block diagram, the power tree and the board outline now carry short block names and short arrow labels, the way the earlier system block diagram did. Part numbers, reference designators, pins and the enable lines move into a block-to-part table on the block diagram page and into the datasheet text around the figures. --- docs/hardware/block-diagram.md | 21 ++ docs/hardware/datasheet.md | 7 + .../images/akidatag-block-diagram.svg | 270 +++++++----------- .../images/akidatag-board-outline.svg | 48 ++-- docs/hardware/images/akidatag-power-tree.svg | 157 +++++----- 5 files changed, 223 insertions(+), 280 deletions(-) diff --git a/docs/hardware/block-diagram.md b/docs/hardware/block-diagram.md index 3ea54cf..fc77cb2 100644 --- a/docs/hardware/block-diagram.md +++ b/docs/hardware/block-diagram.md @@ -28,6 +28,27 @@ MEMS microphones. **Expansion** is the camera header with a level-shifted SPI bu switched 3.3 V supply. **Indicators and controls** are the RGB LED, the white LED and the user button. +| Block | Part | +|---|---| +| nRF5340 | Nordic nRF5340-QKAA (U3); 32 MHz and 32.768 kHz crystals | +| AKD1500 | BrainChip AKD1500 (U7); 25 MHz crystal | +| Flash (MCU), Flash (AI) | Winbond W25Q128JWPIQ, 128 Mbit (IC1, IC2) | +| RF matching, chip antenna | Abracon AMCA31-2R450G-S1F-T3 (AE1); U.FL footprint J3 not fitted | +| 6-axis IMU | STMicroelectronics ISM330DHCX (U5) | +| PDM mic 1, PDM mic 2 | Infineon IM73D122V01XTMA1 (U19, U20) | +| SPI camera header | 10-pin 1.27 mm header J1 behind two SN74AXC2T245 level shifters (U14, U15) | +| Charger + fuel gauge | Texas Instruments BQ25185 (U13) and BQ27427 (U12) | +| On/off switch | Slide switch SW2 | +| Power rails | TPS631000 1.8 V buck-boost (U1), TLV62585 0.8 V buck (U11), TPS7A2033 3.3 V LDO (U16), five TPS22991 load switches, two INA190A3 current-sense amplifiers | +| USB-C | Würth 632722200211 receptacle J5 | +| USB-UART bridge | Silicon Labs CP2105 (U6) | +| SWD header | 10-pin 1.27 mm header J2 | +| RGB LED + white LED | Würth 150505M173300 (D1), Inolux IN-S42ATUW (LED1) | +| User button | Tactile switch SW1 | + +The buses in the figure are detailed in section 3; the power rails and enables in +section 2. + ### Changes from the earlier diagram Revision 2 is the first board shipped, but an earlier system block diagram of the diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index de0191d..3f3b47b 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -59,6 +59,9 @@ is the [block diagram](block-diagram.md) page. ![AkidaTag block diagram](images/akidatag-block-diagram.svg) +The figure names blocks only; the part in each block is in section 3, and the +[block diagram page](block-diagram.md) lists them in one table. + The nRF5340 owns every peripheral. The AKD1500 is a slave on the nRF5340's SPIM4 bus and in turn masters its own NOR flash; the nRF5340 reaches that flash through the AKD1500's feed-through on the second chip select. Power enters from USB-C or the battery, passes @@ -505,6 +508,10 @@ board. ![AkidaTag board outline, top view](images/akidatag-board-outline.svg) +In the drawing: the camera header is J1, the SWD header J2, the U.FL footprint J3, the +battery connector J4, the USB-C receptacle J5, the button SW1, the on/off switch SW2, the +two flashes IC1 (top right) and IC2 (right), and the microphones U19 and U20. + | Item | Value | Source | |---|---|---| | Board size | 27.7 mm x 39.5 mm | Rev2 board outline (DXF) | diff --git a/docs/hardware/images/akidatag-block-diagram.svg b/docs/hardware/images/akidatag-block-diagram.svg index 97fa230..a832683 100644 --- a/docs/hardware/images/akidatag-block-diagram.svg +++ b/docs/hardware/images/akidatag-block-diagram.svg @@ -1,178 +1,118 @@ - + AkidaTag system block diagram, hardware revision 2 - + AkidaTag system block diagram (hardware revision 2) - + POWER SYSTEM - -USB & DEBUG - -COMPUTE & MEMORY + +USB & DEBUG + +COMPUTE & MEMORY RF FRONT-END SENSORS - + EXPANSION - -INDICATORS & CONTROLS - -USB-C J5 -5 V VBUS - -Battery J4 -single-cell Li-ion - -Battery circuit -BQ25185 charger with power path -BQ27427 fuel gauge (I2C) - -On/off switch -SW2 (slide) - -Power rails -TPS631000 1.8 V, TLV62585 0.8 V, TPS7A2033 3.3 V -5 x TPS22991 load switches, 2 x INA190 current sense - - - - -SYS - - -VCC_SYS 3.0 to 4.2 V - - -rails - -USB-C J5 -D+ / D- - -CP2105 -USB-UART bridge - -SWD header J2 -10-pin 1.27 mm - - - -UART0 - - -SWD - -nRF5340 -dual-core Arm Cortex-M33 -128 MHz application core -64 MHz network core -Bluetooth Low Energy -1 MB flash, 512 KB RAM - -Zephyr, MCUboot, LittleFS - -AKD1500 -Akida neuromorphic -AI co-processor -SPI slave host interface -25 MHz crystal, PLL -core clock up to 400 MHz -1 MB on-chip memory -0.8 V core, 1.8 V I/O - -SPI NOR flash IC1 -16 MB, host -update slot + LittleFS - -SPI NOR flash IC2 -16 MB, AI -model storage - - -SPIM4 SPI - -8 to 32 MHz - - -SLEEP, PWR_GOOD - -GPIO0..3 (IRQ) - - -SPIM3 - - -SPI master, quad - - -CS1 - -feed-through: the host reaches IC2 through the AKD1500 - -on SPIM4 chip select 1 - -Both flashes are 128 Mbit SPI NOR; - -IC1 single-lane from the host, IC2 quad from the AKD1500 - -Firmware update slot, LittleFS records and the AKD1500 model - -program all live in external flash; the nRF5340 boots from internal flash - -RF matching -network - -Chip antenna -2.4 GHz -(U.FL footprint, not fitted) - - - -ANT - -6-axis IMU: ISM330DHCX -accelerometer + gyroscope, INT1 - -PDM microphone 1 (U19) -digital MEMS, channel A - -PDM microphone 2 (U20) -digital MEMS, channel B - - -I2C1, 400 kHz - - - -PDM clock + data - -Camera header J1 -10-pin 1.27 mm, level-shifted SPI -switched 3.3 V supply - - -SPI + enables - -RGB LED D1 -white LED LED1 -4 GPIO - -User button SW1 -GPIO P1.01 -(on/off switch: SW2) - - - -GPIO - -Power enables from the nRF5340: P0.19 (AKD1500 1.8 V), P0.20 (IMU), P0.21 (microphones), P0.22 (AKD1500 0.8 V), P1.06 (camera header) - -Current sense outputs into the nRF5340 ADC: AIN0 (1.8 V rail), AIN1 (0.8 V rail) - -Drawn from the revision 2 netlist and bill of materials. Changes from the earlier board: camera header instead of a 20-pin expansion connector, - -one button and an on/off switch instead of three buttons, a 10-pin SWD header, on-board current sensing, and the U.FL connector left unfitted. + +INDICATORS & CONTROLS + +USB-C +5 V + +Battery +connector + +Charger + +fuel gauge + +On/off switch + +Power rails +1.8 V, 0.8 V, 3.3 V + + + + + + +power + +USB-C +D+ / D- + +USB-UART +bridge + +SWD header + + + +UART + + +SWD + +nRF5340 +dual-core MCU +with BLE + +AKD1500 +AI accelerator + +Flash +(MCU) + +Flash +(AI) + + +SPI + + +GPIO + + +SPI + + +QSPI + +RF matching + +Chip antenna + + + +ANT + +6-axis IMU + +PDM mic 1 + +PDM mic 2 + + +I2C + + + +PDM + +SPI camera header + + +SPI + +RGB LED + white LED + +User button + + + +GPIO diff --git a/docs/hardware/images/akidatag-board-outline.svg b/docs/hardware/images/akidatag-board-outline.svg index f779644..c506357 100644 --- a/docs/hardware/images/akidatag-board-outline.svg +++ b/docs/hardware/images/akidatag-board-outline.svg @@ -8,46 +8,44 @@ AkidaTag board outline, top view (hardware revision 2) -nRF5340 +nRF5340 -AKD1500 +AKD1500 -IC1 +Flash -IC2 +Flash -J1 +Camera -J2 +SWD -J3 +U.FL -ANT +Antenna -D1 +RGB LED - +LED -IMU +IMU -CP2105 +USB-UART -FG -CHG +Gauge, charger -SW1 -LED1 +Button -USB-C J5 +USB-C -J4 battery +Battery -SW2 on/off +On/off -mic +Mic -mic +Mic @@ -58,11 +56,9 @@ 27.7 mm 0.889 mm chamfer x4 - + -top-side part +top side -bottom-side part -6-layer PCB, no mounting -holes in the outline data +bottom side diff --git a/docs/hardware/images/akidatag-power-tree.svg b/docs/hardware/images/akidatag-power-tree.svg index c031b41..98da3d6 100644 --- a/docs/hardware/images/akidatag-power-tree.svg +++ b/docs/hardware/images/akidatag-power-tree.svg @@ -1,95 +1,74 @@ - -AkidaTag Rev2 power tree + +AkidaTag power tree, hardware revision 2 - + AkidaTag power tree (hardware revision 2) - -USB-C J5 -VBUS 5 V - -Battery J4 -single-cell Li-ion -3.0 to 4.2 V - -BQ25185 -linear charger -with power path - -BQ27427 -fuel gauge -(in the battery path) - -SW2 -on / off -slide switch - -TPS631000 buck-boost -VDD_1V8 (1.8 V) - -TLV62585 buck -VDD_0V8_AKD (0.8 V) - -TPS7A2033 LDO -EXT_VDD_3V3 (3.3 V) - -LED anodes -RGB LED D1, white LED1 - -nRF5340 -CP2105, flash IC1 - -U10: VDD_1V8_AKD -AKD1500 I/O, flash IC2 - -U4: VDD_1V8_ACC -ISM330DHCX IMU - -U8: VDD_1V8_PDM -2 x PDM microphones - -AKD1500 core -(0.8 V, via 0.02 ohm -INA190 shunt) - -U2: VDD_3V3_1V8_CAM -camera header J1 -+ level shifters - - -5 V - - - -BAT - - -SYS - - - - - -VCC_SYS - -3.0 to 4.2 V - - - - - -0.1 ohm shunt, INA190 U18 - - - -Enables from the nRF5340 -P0.19 U10, P0.20 U4, P0.21 U8, -P0.22 U9, P1.06 U2 - - -P0.22 enables the 0.8 V buck through load switch U9 - -U2, U4, U8, U9 and U10 are TPS22991 load switches; each switched rail stays off until its enable pin is driven high. + +USB-C +5 V + +Battery +3.0 to 4.2 V + +Charger + +Fuel gauge + +On/off switch + +1.8 V buck-boost + +0.8 V buck + +3.3 V LDO + +LEDs + +nRF5340, USB bridge, flash + +AKD1500 I/O + flash +switched + +IMU +switched + +Microphones +switched + +AKD1500 core +switched + +Camera header +switched + + +5 V + + + +BAT + + +SYS + + + + + +VCC_SYS + + + + + +1.8 V + + +0.8 V + + +3.3 V From 348e30627959caca334659f5d837379284ba9e7e Mon Sep 17 00:00:00 2001 From: Nikunj Kotecha Date: Sun, 27 Sep 2026 02:01:56 -0700 Subject: [PATCH 7/7] docs(hardware): drop the unconfirmed values and add the release links The pages go public, so nothing on them is marked as awaiting an answer any more. Values nobody has confirmed (transmit power and range, absolute maximum ratings, temperature and humidity ratings, weight, enclosure dimensions and mounting) are left out, and the consumption figures are stated as coming in a later revision of the document. No firmware version number appears; the pages link to the latest release instead, and they now name the Apache 2.0 licence, the model packages attached to each release, the documentation sites and where to get help or report a bug or a vulnerability. --- docs/hardware/block-diagram.md | 3 +- docs/hardware/datasheet.md | 88 +++++++++-------------- docs/hardware/technical-specifications.md | 27 +++---- 3 files changed, 49 insertions(+), 69 deletions(-) diff --git a/docs/hardware/block-diagram.md b/docs/hardware/block-diagram.md index fc77cb2..626d179 100644 --- a/docs/hardware/block-diagram.md +++ b/docs/hardware/block-diagram.md @@ -9,7 +9,6 @@ the [datasheet](datasheet.md); the buyer-facing summary is the | Document status | | |---|---| | Hardware described | AkidaTag hardware revision 2 | -| Status | Draft for review. Every entry marked `TBD:` is awaiting confirmation; nothing here is estimated. | --- @@ -270,7 +269,7 @@ drawing (January 2026); the Texas Instruments INA190 datasheet (SBOS863D) and BQ datasheet (SLUSEB5B); BrainChip AKD1500 documentation for the strap meanings; and the firmware board overlay `src/boards/nrf5340_cpuapp_akidatag.overlay`, `src/core/interface/gpio/gpio.c`, `src/core/interface/akd_spi_flash/akd_spi_flash_handler.cpp` -and `src/README.md` on `main` at firmware 1.2.0+0. +and `src/README.md` on `main`. --- diff --git a/docs/hardware/datasheet.md b/docs/hardware/datasheet.md index 3f3b47b..e3df473 100644 --- a/docs/hardware/datasheet.md +++ b/docs/hardware/datasheet.md @@ -14,8 +14,7 @@ is the [block diagram](block-diagram.md) page. | Document status | | |---|---| | Hardware described | AkidaTag hardware revision 2, design NRF-AKD1500-002 | -| Firmware referenced | AkidaTag firmware 1.2.0+0, the `main` branch of this repository | -| Status | Draft for review. Every entry marked `TBD:` is a value that no design file, firmware source or datasheet in reach provides, and is awaiting confirmation. Nothing on this page is estimated. | +| Firmware referenced | The AkidaTag firmware in this repository; the current build is the [latest release](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) | --- @@ -202,7 +201,7 @@ Bluetooth Low Energy behaviour is set by the firmware; see section 8. Nordic specifies the nRF5340 radio for a configurable transmit power of -40 to +3 dBm and a receiver sensitivity of -98 dBm at 1 Mbps. The firmware does not set a transmit power, so the Bluetooth controller's default applies. Source: nRF5340 product specification, key -features; `src/prj.conf`. `TBD: transmit power and range measured on this board.` +features; `src/prj.conf`. ### 3.8 USB-C and console @@ -374,7 +373,7 @@ materials. No battery is supplied with the board. Fit a single-cell rechargeable Li-ion or Li-Po cell with a JST XH 2-pin plug, positive on pin 1. The charger regulates the cell to 4.2 V and the -board is designed for 3.0 to 4.2 V on VCC_SYS (section 6.2). +board is designed for 3.0 to 4.2 V on VCC_SYS (section 6.1). ### 5.3 J1, camera header @@ -420,14 +419,10 @@ Source: Rev2 netlist. ## 6. Electrical characteristics -No board-level electrical characterisation is available in the sources this page is -built from. The rows below record what the design sets; every measured value is marked. +The values below are the settings the revision 2 design makes. Measured characteristics +will be added in a later revision of this document. -### 6.1 Absolute maximum ratings - -`TBD: absolute maximum ratings.` None have been established for the assembly. - -### 6.2 Recommended operating conditions +### 6.1 Recommended operating conditions | Parameter | Min | Typ | Max | Unit | Source | |---|---|---|---|---|---| @@ -437,26 +432,19 @@ built from. The rows below record what the design sets; every measured value is | VDD_0V8_AKD core rail | | 0.8 | | V | Rev2 schematic | | EXT_VDD_3V3 camera rail | | 3.3 | | V | Rev2 schematic | | Camera header supply | | 3.3 (1.8 option not fitted) | | V | Rev2 netlist | -| Operating temperature | `TBD: operating temperature range` | | | °C | Not rated for the assembly. The nRF5340 is rated -40 to 105 °C (Nordic) and the charger -40 to 125 °C junction (TI); the other parts and the cell fitted narrow this | - -### 6.3 Current consumption - -Current consumption per state (asleep and advertising, connected and idle, keyword -spotting running, peak during an inference) and the charge current drawn from USB will be -measured on a revision 2 board and added in a later revision of this datasheet. -`TBD: current consumption, deferred to a later revision.` Until then the only current -figure on this page is the charger's 536 mA nominal fast-charge setting in section 3.11. - -No board-level consumption has been measured yet. The firmware measures the 1.8 V and -0.8 V rails itself through the INA190 amplifiers (`power read`, `power measure`), which is -the way to fill in the rows for the rails behind them: the shunts are 0.1 ohm on the 1.8 V -rail and 0.02 ohm on the 0.8 V rail, and revision 2 fits the 100 V/V amplifier, so run -`power variant a3` first because the firmware's build-time default is the 25 V/V A1 part. -The total draw, which also covers the charger, the LEDs and the 3.3 V rail, needs a meter in -series with the battery or the USB input. Source: Rev2 bill of materials, `src/README.md`. -The only board test records available, the post-fabrication PCB test report of March 2026 -and the PCB testing checklist of February 2026, cover bare-board impedance and short/open -checks and the power-on procedure, and contain no current measurements. + +### 6.2 Current consumption + +Power consumption figures, per operating state and for the charge current drawn from USB, +will be added in a later revision of this document. The charger's 536 mA nominal +fast-charge setting is in section 3.11. + +The firmware measures the 1.8 V and 0.8 V rails itself through the INA190 amplifiers +(`power read`, `power measure`): the shunts are 0.1 ohm on the 1.8 V rail and 0.02 ohm on +the 0.8 V rail, and revision 2 fits the 100 V/V amplifier, so run `power variant a3` first +because the firmware's build-time default is the 25 V/V A1 part. The total draw, which +also covers the charger, the LEDs and the 3.3 V rail, needs a meter in series with the +battery or the USB input. Source: Rev2 bill of materials, `src/README.md`. What the on-board measurement can resolve follows from the INA190 datasheet. The A3 device has a gain error of plus or minus 0.3 % and a zero-current output offset of up to 3 mV at a @@ -500,7 +488,7 @@ board. | Firmware update over USB-C | MCUboot serial recovery on the CP2105 UART, entered without a button | [firmware update over USB](../firmware-update-over-usb.md) | | Console | Zephyr shell on UART0 at 115200 8N1 | `src/prj.conf`, board overlay | | Watchdog | 8 s application watchdog | `src/prj.conf` | -| Firmware version | 1.2.0+0, readable over Bluetooth with `smpmgr image state-read` | `VERSION`, `AGENTS.md` | +| Firmware version | Readable over Bluetooth with `smpmgr image state-read`; the current build is the [latest release](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) | `VERSION`, `AGENTS.md` | --- @@ -517,37 +505,29 @@ two flashes IC1 (top right) and IC2 (right), and the microphones U19 and U20. | Board size | 27.7 mm x 39.5 mm | Rev2 board outline (DXF) | | Corners | 0.889 mm chamfer on all four corners | Rev2 board outline (DXF) | | Layer count | 6 | Rev2 fabrication artwork layer set | -| Mounting holes | None found in the outline data; `TBD: mounting provisions` | Rev2 board outline (DXF) | +| Mounting holes | None | Rev2 board outline (DXF) | | USB-C position | Bottom side, centred near one short edge, receptacle projecting beyond the edge | Rev2 placement data | | Microphones | Bottom side, one in each corner beside the USB-C edge | Rev2 placement data | | Board thickness | 1.00 mm, plus or minus 10 % | Rev2 fabrication notes | -| Weight | `TBD: weight` | | -| Enclosure | The board ships in its enclosure; `TBD: enclosure dimensions and material` | BrainChip product decision | - ---- - -## 10. Environmental - -| Item | Value | -|---|---| -| Operating temperature | `TBD: operating temperature range`; not rated for the assembly, see section 6.2 | -| Storage temperature | `TBD: storage temperature range` | -| Humidity | `TBD: humidity range` | +| Enclosure | The board ships in its enclosure | BrainChip product decision | --- -## 11. Product information +## 10. Product information | Item | Value | |---|---| | Product name | AkidaTag | | What is in the box | The AkidaTag board in its enclosure. No battery, USB-C cable or camera is included | -| Companion app | BrainChip Connect for Android 13 or later; the [Google Play listing](https://play.google.com/store/apps/details?id=com.brainchip.connect) is open for pre-registration and the app is not yet installable from it. An iOS version is to follow on the App Store | -| Developer resources | [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/), [Developer Hub sign-up](https://developer.brainchip.com/signup/), [BrainChip community on Discord](https://discord.com/invite/9bmd9g52vn) | +| Companion app | BrainChip Connect for Android 13 or later, in [pre-registration on Google Play](https://play.google.com/store/apps/details?id=com.brainchip.connect), and coming soon to the iOS App Store | +| Firmware and models | The [latest firmware release](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) of this repository; every release attaches the model packages `akidatag-kws-model.zip` and `akidatag-kws-edge-learning-model.zip` | +| Licence | Apache License 2.0, in `LICENSE` at the root of this repository | +| Documentation | [AkidaTag documentation](https://brainchip-inc.github.io/AkidaTag/), [BrainChip Connect documentation](https://brainchip-inc.github.io/BrainChip-Connect/), [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/) and [Developer Hub sign-up](https://developer.brainchip.com/signup/) | +| Support | Help on the [BrainChip Discord](https://discord.com/invite/9bmd9g52vn); bugs as [GitHub issues](https://github.com/Brainchip-Inc/AkidaTag/issues); security problems reported privately through the repository's Security tab ("Report a vulnerability") | --- -## 12. Revision history +## 11. Revision history ### Hardware @@ -562,16 +542,16 @@ first board shipped. Source: the revision summary on the Rev2 schematic cover sh | Date | Change | |---|---| -| 2026-09-25 | First draft from the revision 2 design files and firmware 1.2.0+0 | +| 2026-09-25 | First edition, from the revision 2 design files and the firmware on `main` | --- -## 13. Sources +## 12. Sources - Revision 2 design files: schematic SI-NRF-AKD_BRD-002 V11 (2026-08-25), bill of materials NRF-AKD1500-002 V11, netlist report (2026-08-24), placement file, board outline DXF and fabrication artwork set. -- Firmware on `main` at 1.2.0+0: `src/boards/nrf5340_cpuapp_akidatag.overlay`, +- Firmware on `main` of this repository: `src/boards/nrf5340_cpuapp_akidatag.overlay`, `src/sysbuild/mcuboot_akidatag.overlay`, `src/sysbuild/mcuboot.conf`, `src/prj.conf`, `src/Kconfig`, `src/pm_static.yml`, `src/apps/demo_apps/custom_app.conf`, `src/imu_app.conf`, `src/README.md`, `src/core/interface/gpio/gpio.c`, @@ -585,9 +565,9 @@ first board shipped. Source: the revision summary on the Rev2 schematic cover sh charging thresholds and timers. - Texas Instruments INA190 datasheet, SBOS863D: gain options, gain error, zero-current output offset and output swing. -- Board test records, internal: post-fabrication PCB test report (version 1.0, 2026-03-13), +- BrainChip board test records: post-fabrication PCB test report (version 1.0, 2026-03-13), PCB testing checklist and procedures (version 1.0, 2026-02-18) and Spark board SWD - connection guide (version 1.1, 2026-04-10); read for facts only, nothing copied. + connection guide (version 1.1, 2026-04-10). - BrainChip AKD1500 documentation for the strap meanings and the Safe Mode clock behaviour. - Texas Instruments BQ27427 datasheet, SLUSEB5B: pin functions. - BrainChip product decisions of September 2026: the enclosure ships with the board, the box diff --git a/docs/hardware/technical-specifications.md b/docs/hardware/technical-specifications.md index a3d342c..a4a5239 100644 --- a/docs/hardware/technical-specifications.md +++ b/docs/hardware/technical-specifications.md @@ -15,8 +15,7 @@ the [block diagram](block-diagram.md). | Document status | | |---|---| | Hardware described | AkidaTag hardware revision 2 | -| Firmware referenced | AkidaTag firmware 1.2.0+0 | -| Status | Draft for review. Every entry marked `TBD:` is awaiting confirmation; nothing here is estimated. | +| Firmware referenced | The AkidaTag firmware in this repository; the current build is the [latest release](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) | --- @@ -64,22 +63,17 @@ the [block diagram](block-diagram.md). | **Power monitoring** | On-board current sensing of the 1.8 V system rail and the 0.8 V AI core rail, readable from the firmware console | | **Bluetooth** | Bluetooth Low Energy peripheral, device name `AkidaTag`; LE Secure Connections only with bonding; firmware update over Bluetooth | | **Radio** | nRF5340 radio, specified by Nordic for -40 to +3 dBm configurable transmit power and -98 dBm sensitivity at 1 Mbps; on-board 2.4 GHz chip antenna | -| **Bluetooth range** | `TBD: Bluetooth range` | | **USB** | USB-C: 5 V charging input and a USB-to-serial console at 115200 baud; firmware update over the cable with nothing but a computer | | **Debug** | 10-pin 1.27 mm SWD header | | **Battery** | Not included. Fits a single-cell rechargeable Li-ion or Li-Po cell, 3.0 to 4.2 V, on a JST XH 2-pin connector | | **Battery life** | Depends on the cell fitted | | **Charging** | On-board linear charger with power path, 536 mA nominal fast charge from USB-C 5 V; the device runs while charging; charge time depends on the cell fitted | | **Power switch** | On/off slide switch | -| **Power consumption** | `TBD: power consumption, to be measured for a later revision` | +| **Power consumption** | Power consumption figures will be added in a later revision of this document | | **Indicators** | One RGB LED and one white LED under firmware control | | **Controls** | One user button; the on/off slide switch | | **Board dimensions** | 27.7 mm x 39.5 mm, 1.0 mm thick, six-layer PCB, chamfered corners | -| **Enclosure** | Ships in its enclosure; `TBD: enclosure dimensions, material and colour` | -| **Weight** | `TBD: weight` | -| **Operating temperature** | `TBD: operating temperature range`; the board as a whole has not been rated, and the host processor is rated -40 to 105 °C | -| **Storage temperature** | `TBD: storage temperature range` | -| **Humidity** | `TBD: humidity range` | +| **Enclosure** | Ships in its enclosure | | **What is in the box** | The AkidaTag board in its enclosure. No battery, USB-C cable or camera is included | --- @@ -95,24 +89,31 @@ USB-C cable from a computer. | | | |---|---| -| **Companion app** | BrainChip Connect for Android 13 or later. The Google Play listing is open for pre-registration; the app is not yet installable from it. An iOS version is to follow on the App Store | -| **Firmware** | This repository, open for building and modification | +| **Companion app** | BrainChip Connect for Android 13 or later, in pre-registration on Google Play, and coming soon to the iOS App Store | +| **Firmware** | This repository, under the Apache License 2.0; the current build is the [latest release](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) | +| **Models** | Every firmware release attaches the keyword spotting model packages `akidatag-kws-model.zip` and `akidatag-kws-edge-learning-model.zip` | | **Demonstrations** | Keyword spotting with on-device edge learning; motion sensing; camera capture | ## Resources +- [AkidaTag documentation](https://brainchip-inc.github.io/AkidaTag/) +- [BrainChip Connect documentation](https://brainchip-inc.github.io/BrainChip-Connect/) +- [AkidaTag firmware releases](https://github.com/Brainchip-Inc/AkidaTag/releases/latest) - [AkidaTag on the BrainChip Developer Hub](https://developer.brainchip.com/akida-tag/) - [Developer Hub sign-up](https://developer.brainchip.com/signup/) - [BrainChip Connect on Google Play (pre-registration)](https://play.google.com/store/apps/details?id=com.brainchip.connect) -- [BrainChip community on Discord](https://discord.com/invite/9bmd9g52vn) - [AKD1500 product brief](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf) +- Help: the [BrainChip Discord](https://discord.com/invite/9bmd9g52vn) for questions and + [GitHub issues](https://github.com/Brainchip-Inc/AkidaTag/issues) for bugs. Security + problems are reported privately through the repository's Security tab + ("Report a vulnerability") --- ## Sources Every value on this page is taken from the AkidaTag revision 2 design files, the AkidaTag -firmware 1.2.0+0 in this repository, the +firmware in this repository, the [AKD1500 Product Brief V2.4](https://brainchip.com/wp-content/uploads/2025/10/AKD1500-Product-Brief-V2.4-Oct.25.pdf), the [Nordic nRF5340 product specification](https://docs.nordicsemi.com/bundle/ps_nrf5340/page/keyfeatures_html5.html), the Texas Instruments BQ25185 datasheet, the