Parallel IR Transmitter System

A scalable IR transmission platform with dual implementations: 24-channel parallel FPGA-based transmitter (PYNQ-Z2) and Arduino-only alternative. Decode and test IR signals using dual Arduino Uno receivers with NEC-inspired protocol support.

📋 Table of Contents

Project Overview
System Architecture
Transmitter Circuitry
Project Structure
Hardware Setup
Software Setup & Installation
Usage Guide
IR Protocol Specification
Customization & Development
Troubleshooting
Appendix

🔍 Project Overview

This project implements a high-capacity parallel IR transmission system designed for:

Research & Testing: Transmit multiple IR signals simultaneously to evaluate receiver performance
Device Control: Send NEC-compatible IR commands to multiple devices in parallel
System Integration: Flexible architecture supporting both FPGA and Arduino implementations

Key Features:

✅ 24 parallel IR transmitter channels (FPGA version) — TESTED & WORKING
✅ Simultaneous multi-channel transmission with independent control
✅ Dual Arduino receiver validation setup
✅ NEC IR protocol support with custom extensions
✅ Low-cost Arduino-only fallback implementation
✅ Real-time signal monitoring and debugging

⚠️ Status: FPGA IR receiver (PL design) is NOT YET TESTED. Transmitter functionality is stable. Use external Arduino receivers for validation.

🏗 System Architecture

Two Implementation Approaches

Aspect	FPGA Version	Arduino Version
Transmitter	PYNQ-Z2 FPGA (24 channels)	Arduino Uno (1 channel)
Receivers	2× Arduino Uno or external receiver	1× Arduino + external receiver
Complexity	Advanced (Vivado design)	Simple (single sketch)
Cost	Higher	Lower
Scalability	24 parallel channels	Single sequential channel
Use Case	Bulk testing, research	Hobbyist, simple control

FPGA System Block Diagram

PYNQ-Z2 Board
├─ Processing System (PS) — ✅ TESTED
│  └─ Python/Jupyter Controller (nec_onlyFPGA.ipynb)
├─ Programmable Logic (PL)
│  ├─ NEC_IR_Receiver IP cores (×2) — ⚠️ NOT YET TESTED
│  ├─ IR_Transmission IP cores (×24) — ✅ TESTED
│  └─ AXI GPIO interfaces
└─ Physical I/O
   ├─ 24× IR LED outputs (AR0-AR13, A0-A5, PMODA) — ✅ TESTED
   └─ 2× status/control pins

Receiver Setup (External - Recommended)
├─ Arduino Uno (Blue) → Pin 11 (Receiver 1) — ✅ TESTED
└─ Arduino Uno (Green) → Pin 10 (Receiver 2) — ✅ TESTED

📁 Project Structure

Parallel_IR_Transmitters/
│
├── 📄 README.md                          # This file
├── 📄 IR_research.pdf                    # research that I conduct now
|── 📄 main.tex                           #The LaTeX file of my Research  
│
├── 📂 PS\ part/                          # FPGA Processing System (PS) - Python Side
│   ├── 📓 nec_onlyFPGA.ipynb            # Jupyter notebook for PYNQ-Z2
│   │                                    # - NEC_IR_Controller_24ch class
│   │                                    # - Command transmission logic
│   │                                    # - Real-time control interface
│   │
│   ├── 📂 xilinx/overlays/own/
│   │   ├── design_1_wrapper.bit         # FPGA bitstream file
│   │   └── design_1_wrapper.hwh         # Hardware handoff file
│   │
│   └── 📂 arduino\ part/
│       ├── 📂 IR_TransmitterReceiver/   # Receiver sketch (standard)
│       │   └── IR_TransmitterReceiver.ino
│       └── 📂 IR_Receiver2/             # Receiver sketch (variant)
│           └── IR_Receiver2.ino
|       └── 📂 Voltmetr/             # Receiver sketch (variant)
│           └── Voltmetr.ino
|            └── Board_Voltmetr.txt
│
├── 📂 FPGA_Part/                         # FPGA Programmable Logic (PL) - Vivado Design
│   ├── 📂 Own_IR_receiver/              # Vivado project (receiver reference) ⚠️ NOT TESTED
│   │   ├── Own_IR_Receiver.xpr
│   │   ├── design_1_wrapper.bit
│   │   └── [Vivado build artifacts]
│   │
│   └── 📂 Own_IR_transmitter/           # Vivado project (24-channel transmitter) ✅ TESTED
│       ├── Own_IR_transmitter.xpr
│       ├── design_1_wrapper.xsa
│       └── [Vivado build artifacts]
│
├── 📂 external_design/                   # Circuit Design Files
│   ├── External_circuit.asc             # 24 VCC GND port (SPICE)
│   ├── Safe_Driving_Circuit.asc         # Protected driver circuit (SPICE)
│   ├── Driving_Ciruit.asc               # Alternative driver (SPICE)
│   └── 📂 Altium/                       # PCB Design (Altium Designer)
│       ├── 📂 24_external/              # 24-channel external driver PCB
│       │   ├── PcbLib1.PcbLib
│       │   ├── PCB_Project/
│       │   └── __Previews/
│       └── 📂 Driving_Circuit/          # Driving circuit PCB
│           └── Control_Circuit_safe/
│
├── 📂 No_FPGA_approach/                  # Arduino-Only Alternative
│   └── 📂 IR_transmitter/
│       └── IR_transmitter.ino           # Standalone Arduino TX sketch
│
├── 📂 Metasurface\ research_papers/     # Research Reading Materials
│   ├── My\ list.txt                     # Curated reading list
│   └── 📂 Step0/                        # Research progress notes
│       └── Step\ to\ take\ here.txt
│
└── 📂 img/                               # Hardware photos & diagrams
    ├── WhatsApp\ Image\ 2026-03-09\ at\ 17.52.39.jpeg
    ├── image-1.png
    ├── image-2.png
    ├── image-3.png
    └── Image_for_more.png

� PCB Design & Altium Documentation

Altium PCB Files

The external_design/Altium/ folder contains complete PCB designs created with Altium Designer:

24-Channel External Driver PCB

Directory: external_design/Altium/24_external/
Purpose: Dedicated driver PCB for all 24 parallel IR LED transmitters
Features:
- 24 independent driver channels with current limiting
- Thermal management and RF shielding considerations
- Integration connectors for FPGA board
- PCB Library files and design projects included

Driving Circuit PCB

Directory: external_design/Altium/Driving_Circuit/
Purpose: Individual IR LED driver circuit design
Features:
- Optimized for single or multi-channel configurations
- Safe switching circuitry with transient suppression
- References corresponding SPICE simulations in external_design/

SPICE Simulation Files

Complementary SPICE circuit files for simulation and verification:

External_circuit.asc — 24-port external interface with VCC/GND distribution
Safe_Driving_Circuit.asc — Protected driver with feedback and current monitoring

Recommendation: Review SPICE simulations before PCB manufacturing to validate signal integrity and power delivery.

🔌 Transmitter Circuitry

The current hardware work uses two closely related IR transmitter circuits. Both use the same AO3400A low-side MOSFET driver and are controlled by the PYNQ-Z2 FPGA's 3.3 V NEC-modulated output. The IR LEDs are powered from a separate regulated 5 V supply, with the FPGA ground and 5 V supply ground connected together.

Circuit 1 — Two-LED Series Transmitter

This is the higher-output transmitter configuration used in the main design. Two TSAL6200 IR emitters are connected in series and switched by one AO3400A MOSFET.

                +5 V
                  |
             TSAL6200
                  |
             TSAL6200
                  |
             30 Ω / 0.5 W
                  |
                Drain
              AO3400A
                Source
                  |
                 GND

FPGA GPIO ── 330 Ω ── Gate
                       |
                      10 kΩ
                       |
                      GND

With a typical LED forward voltage of approximately 1.35 V per TSAL6200,

I ≈ (5 V - 2×1.35 V) / 30 Ω
  ≈ 76.7 mA

so both LEDs carry approximately 77 mA while the MOSFET is ON.

An optional second identical branch can be added if more optical power is required. Each parallel branch must have its own 30 Ω current-limiting resistor.

Circuit 2 — Single-LED Transmitter

A second test configuration uses only one TSAL6200. The MOSFET driver remains the same, but the LED resistor must be increased because there is only one LED forward-voltage drop.

                +5 V
                  |
             TSAL6200
                  |
             47 Ω / 0.5 W
                  |
                Drain
              AO3400A
                Source
                  |
                 GND

FPGA GPIO ── 330 Ω ── Gate
                       |
                      10 kΩ
                       |
                      GND

The approximate current is

I ≈ (5 V - 1.35 V) / 47 Ω
  ≈ 77.7 mA

so the single LED also operates at approximately 78 mA.

The old 30 Ω resistor must not be used with only one LED, because the estimated current would become approximately

I ≈ (5 V - 1.35 V) / 30 Ω
  ≈ 122 mA

which is above the intended operating current.

Components Shared by Both Circuits

Component	Value / Part	Purpose
IR emitter	TSAL6200, 940 nm	Directional IR transmission
MOSFET	AO3400A	Low-side LED switching
Gate resistor	330 Ω, 1/4 W	Limits FPGA gate charging current
Gate pull-down	10 kΩ, 1/4 W	Keeps MOSFET OFF during startup/reset
Bulk capacitor	100 µF, ≥10 V	Local energy storage
Decoupling capacitor	1 µF ceramic	Supply decoupling
High-frequency capacitor	100 nF ceramic	High-frequency decoupling
LED supply	Regulated 5 V	Supplies LED current
Control input	3.3 V FPGA logic	NEC-modulated 38 kHz switching signal

The single-LED circuit is useful as a minimum-power test configuration. If one emitter already gives reliable reception at the required receiver positions, it may reduce unnecessary optical spill into neighboring receiver regions. It does not completely remove interference from other independent transmitters.

📚 Research & Readings

Research Materials

Located in Metasurface\ research_papers/ folder:

My list.txt — Curated list of important research papers and technical references related to the project
Step0/ — Research progress notes and next steps for metasurface and IR transmission investigations

Relevant Topics Covered

IR transmission physics and optimization
Metasurface applications for RF/IR engineering
Signal processing and modulation techniques
High-speed parallel data transmission

📖 Note: These materials provide theoretical background and advanced optimization strategies for future enhancements.

�🛠 Hardware Setup

Components Required (FPGA Version)

Component	Quantity	Purpose
PYNQ-Z2 FPGA Board	1	Main controller (24-channel TX)
Arduino Uno	2	IR signal receivers + validation
IR LED Emitter	24	Transmitter elements (FPGA outputs)
IR Receiver Module	2	Signal decoders (1 per Arduino)
Driver Circuit	24	LED current limiting & switching
Copper sheet / barrier	1	RF isolation between TX channels
Jumper wires	~100	Interconnections
USB cables	3	PYNQ power, Arduino programming
Ethernet cable	1	PYNQ network (optional but recommended)

Components Required (Arduino-Only Version)

Component	Quantity	Purpose
Arduino Uno	1	IR transmitter controller
IR LED Emitter	1	Transmitter element
Driver Circuit	1	LED current limiting
Jumper wires	~60	Interconnections
USB cable	1	Power & programming

🔌 Wiring Connections (FPGA Version)

FPGA (PYNQ-Z2) → IR Transmitter Drivers

Channel	PYNQ-Z2 Pin	Driver Output
1-8	AR0-AR7	IR LED Array 1
9-13	AR8-AR12	IR LED Array 2
14-19	A0-A5	IR LED Array 3
20-24	PMODA0-PMODA4	IR LED Array 4

Each pin: 3.3V logic → Buffer/Driver → IR LED anode (cathode to GND through 100Ω resistor)

PYNQ-Z2 → Micro-USB Port (Power)

⚡ Micro-USB cable to computer or dedicated 5V supply

PYNQ-Z2 → Ethernet

🌐 Gigabit Ethernet cable for robust network connection to Jupyter server

Arduino 1 (Blue Board) → IR Receiver 1

Component	Pin
IR Receiver Data	GPIO 11
IR Receiver VCC	5V
IR Receiver GND	GND

Arduino 2 (Green Board) → IR Receiver 2

Component	Pin
IR Receiver Data	GPIO 10
IR Receiver VCC	5V
IR Receiver GND	GND

Arduino 1 & 2 → Computer (Programming/Monitoring)

USB cables to different COM ports

📷 Hardware Photos

Click to expand hardware documentation

FPGA Board + 24 IR Transmitter Array:

Arduino 1 (Blue) with IR Receiver Module:

Arduino 2 (Green) with IR Receiver Module:

Complete System Architecture:

RF Isolation Barrier (Copper Sheet for Channel Separation):

Reference Network Config:

💻 Software Setup & Installation

Prerequisites

PYNQ-Z2 board with latest firmware
2× Arduino Uno boards
Computer with USB ports
Python 3.6+ (for local scripts)
Arduino IDE 1.8+ (for sketches)

Option A: FPGA-Based Setup (Recommended for 24-channel)

Step 1: PYNQ-Z2 Network Setup

Connect PYNQ-Z2 via Micro-USB and Ethernet to your network
Power on and wait 2-3 minutes for boot
Find the board's IP address (default: 192.168.2.99)
Reference: PYNQ Setup Guide

Step 2: Access Jupyter Server

Open browser: http://192.168.2.99:9090/
Password: xilinx
Create a working folder (e.g., IR_Project)

Step 3: Upload FPGA Bitstream & Controller

Upload to PYNQ Jupyter server:

Local File	Server Destination
`PS\ part/nec_onlyFPGA.ipynb`	`~/IR_Project/`
`PS\ part/xilinx/overlays/own/design_1_wrapper.bit`	`~/IR_Project/xilinx/overlays/own/`
`PS\ part/xilinx/overlays/own/design_1_wrapper.hwh`	`~/IR_Project/xilinx/overlays/own/`

Step 4: Install Arduino Receiver Firmware

Open Arduino IDE
Install library: Arduino-IRremote (Sketch → Include Library → Manage Libraries)
Load: PS\ part/arduino\ part/IR_TransmitterReceiver/IR_TransmitterReceiver.ino
Select Tools → Board → Arduino Uno
Connect Arduino 1, select its COM port, upload
Repeat with Arduino 2 on a different COM port

Step 5: Verify Connection

Open both Arduino Serial Monitors (9600 baud)
Run Jupyter notebook test cell
Should see "Overlay loaded" message

Option B: Arduino-Only Setup (Budget alternative)

Open Arduino IDE
Install Arduino-IRremote library
Load: No_FPGA_approach/IR_transmitter/IR_transmitter.ino
Modify pin assignments if needed (currently D2)
Upload to single Arduino Uno
Connect IR LED via driver circuit to D2 pin
Open Serial Monitor (9600 baud) to send commands

🚀 Usage Guide

FPGA Version - Transmitting IR Signals

Launch Jupyter Notebook

On PYNQ server: Open nec_onlyFPGA.ipynb
Run cell 1: Loads NEC_IR_Controller_24ch class and initializes FPGA

Transmit Commands

Example 1: Send commands

# In notebook cell:
controller = NEC_IR_Controller_24ch(

    ir = NEC_IR_Controller_24ch(
        "/home/xilinx/jupyter_notebooks/xilinx/overlays/own/design_1_wrapper.bit",
        tx_bases=tx_bases,
        btn_base=btn_base
    )

    try:
        start = datetime.now()
        # Each tx needs address and a command string of equal length
        tx_addresses =  [0x00]*24
             # Example addresses
        cmd_strs = [
            "-0001+",  # Channel 0: 5
            "-0013+",  # Channel 1: 6
            "-0106+",  # Channel 2: 7
            "-0008+",  # Channel 3: 8
            "-0009+",  # Channel 4: 9
            "-0010+",  # Channel 5: 10
            "-0011+",  # Channel 6: 11
            "-0012+",  # Channel 7: 12
            "-0013+",  # Channel 8: 13
            "-0014+",  # Channel 9: 14
            "-0015+",  # Channel 10: 15
            "-0016+",  # Channel 11: 16
            "-0017+",  # Channel 12: 17
            "-0018+",  # Channel 13: 18
            "-0019+",  # Channel 14: 19
            "-0020+",  # Channel 15: 20
            "-0021+",  # Channel 16: 21
            "-0022+",  # Channel 17: 22
            "-0023+",  # Channel 18: 23
            "-0024+",  # Channel 19: 24
            "-0025+",  # Channel 20: 25
            "-0026+",  # Channel 21: 26
            "-0027+",  # Channel 22: 27
            "-0028+",  # Channel 23: 28
        ]
)

# Transmit on channels 1 and 2 simultaneously
controller.send_cmd(0, '1')  # Transmitter 0, command '1'
controller.send_cmd(1, 'B')  # Transmitter 1, command 'B'

Monitor Reception

Check Serial Monitor on each Arduino
Output format: Address: 0xXX, Command: 0xXX
Timing: Signals should arrive within 100ms

Arduino-Only Version - Transmitting IR Signals

Serial Interface

Open Arduino Serial Monitor at 9600 baud
Type a character and press Enter
Predefined mappings (0-9, A-F) send NEC codes
Received signals can be monitored with external receiver

Add Custom Codes

Edit the Send_Code() function:

case 'X':
  IrSender.sendNEC(0x12345678, 32);
  break;

📡 IR Protocol Specification

Protocol Overview

Parameter	Value	Notes
Standard	NEC-compatible	Simplified NEC implementation
Total Frame Bits	32 bits	Address + Command + Parity
Address Bits	8 bits	Device identifier
Command Bits	8 bits	Action/button code
Carrier Frequency	~38 kHz	Standard IR frequency
Modulation	PWM (50% duty)	On-off keying
Protocol Channels	24 (parallel FPGA)	Independent TX channels

Frame Structure

┌─ 32 bits total ─┐
│ Address (8b) │ Command (8b) │ ~Address (8b) │ ~Command (8b) │
└────────────────┘

Address Field: Device identifier (0x00-0xFF)
Command Field: Action code (0x00-0xFF)
Inverse Fields: Checksum/error detection

Default Command Mapping

Key	Code	Key	Code
0	0x16	8	0x52
1	0x0C	9	0x4A
2	0x18	A	0xAA
3	0x5E	B	0xBB
4	0x08	C	0xCC
5	0x1C	D	0xDD
6	0x5A	E	0xEE
7	0x42	F	0xF1

� Current Testing Status

✅ Fully Tested & Stable

FPGA Transmitter (24 channels): All transmitter channels working as designed
Arduino Receivers: Both receiver boards successfully decode NEC signals
Python/Jupyter Interface: Notebook controller and MMIO communication verified
Protocol Implementation: Standard NEC encoding/decoding functional

⚠️ Not Yet Tested

FPGA Receiver (PL design): NEC_IR_Receiver IP cores in the FPGA bitstream have not been validated
- Reason: Focus was on transmission performance; receiver testing deferred
- Recommendation: Use external Arduino receivers for current applications
- Future: Will integrate FPGA receiver testing in next release

📝 Known Limitations

FPGA receiver functionality cannot be guaranteed in production
No loopback testing between FPGA TX and FPGA RX
All receiver-side validation currently relies on Arduino Uno boards and external circuits

�🐛 Troubleshooting

FPGA Connection Issues

Symptom	Cause	Solution
No Jupyter server response	Board not powered	Check USB power indicator LED
Connection timeout	Network misconfiguration	Ping board IP: `ping 192.168.2.99`
Overlay failed to load	Bitstream path incorrect	Verify `.bit` and `.hwh` files exist in correct directory
MMIO initialization error	Wrong base address	Verify address map in Vivado design

IR Transmission Issues

Symptom	Cause	Solution
No IR signal	LED not powered	Check driver circuit continuity (multimeter)
Weak/short-range signal	Insufficient LED current	Reduce resistor value (100Ω → 50Ω)
No receiver output	Receiver placement	Point LED directly at receiver (within 1 meter)
Garbled data	Baud rate mismatch	Set both Arduino + Serial Monitor to 9600 baud
Channel interference	No RF isolation	Place copper barrier between TX LED arrays

Arduino Issues

Symptom	Cause	Solution
Sketch upload fails	Wrong COM port	Tools → Port → Select correct COM port
Serial Monitor shows garbage	Baud mismatch	Set Serial Monitor to 9600 baud
Library not found	IRremote not installed	Sketch → Include Library → Manage Libraries → Search "IRremote" → Install

Performance Issues

Symptom	Cause	Solution
Slow transmission	Jupyter kernel lag	Restart kernel: Kernel → Restart
Dropped frames	High FPGA load	Increase delay between transmissions (`NEC_HOLD_TIME`)
Inconsistent reception	Weak carrier frequency	Verify crystal oscillator on FPGA board

📚 Appendix

External Resources

PYNQ Official Documentation: https://pynq.readthedocs.io/
Vivado Design Suite: https://www.xilinx.com/products/design-tools/vivado.html
NEC IR Protocol: https://www.sbprojects.net/knowledge/ir/nec.php
Arduino-IRremote Library: https://github.com/Arduino-IRremote/Arduino-IRremote

Circuit Design References

PCB Design Files:

external_design/Altium/24_external/ — Complete 24-channel driver PCB (Altium Designer)
external_design/Altium/Driving_Circuit/ — Individual LED driver PCB design

SPICE Circuit Simulations:

external_design/External_circuit.asc — VCC GND distribution circuit
external_design/Safe_Driving_Circuit.asc — Protected version with feedback
external_design/Driving_Ciruit.asc — Standard IR LED driver

Research & Technical Papers

Metasurface\ research_papers/My\ list.txt — Curated reading list for IR transmission and metasurface topics
Metasurface\ research_papers/Step0/ — Research progress notes and investigation roadmap

File Descriptions

nec_onlyFPGA.ipynb: Main control interface for 24-channel transmission
IR_research.pdf: Research in a topic
Own_IR_transmitter.xpr: Vivado project (24-channel implementation)
Own_IR_receiver.xpr: Vivado project (receiver reference design)

License & Attribution

This project builds upon:

PYNQ framework (Xilinx/University of Sydney)
Arduino IDE & libraries (Arduino LLC)
NEC IR protocol (reverse-engineered standard)

Last Updated: June 2026
Status: Transmitter Stable | Receiver Under Development | PCB Design Complete

Name		Name	Last commit message	Last commit date
FPGA_Part		FPGA_Part
Metasurface research_papers		Metasurface research_papers
No_FPGA_approach/IR_transmitter		No_FPGA_approach/IR_transmitter
PS part		PS part
external_design		external_design
img		img
IR_research.pdf		IR_research.pdf
README.md		README.md
main (1).tex		main (1).tex

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