A compact, low-power IoT air quality node — power-latched, boost-regulated, and ADC-accurate.
This project implements a battery-powered air quality monitoring system built around the ESP32, engineered for long-duration, low-standby-power IoT deployment. A soft power latch lets a single push of a button wake the whole board, while the ESP32 firmware decides when to shut everything back down — driving standby current to near zero between readings.
🔋 Designed for real-world battery life. Simulated and validated end-to-end in eSim, as part of the FOSSEE Research Migration Project, IIT Bombay.
| 🔧 Component | 🎯 Role |
|---|---|
| ⚡ IRLML6401 + MMBT3904 Soft Power Latch | Push-button power-on, firmware-controlled power-off — kills standby drain |
| 🔺 MCP16251 Boost Converter | Steps up battery voltage to a clean, regulated supply rail |
| 🧠 ESP32 Dev Board | Main controller — manages latch hold, sensing, and I²C comms |
| 📈 ADS1115 16-bit ADC | High-resolution analog-to-digital conversion over I²C |
| 🔌 JST Connector | Plug-and-play interface for an external air-quality sensor |
| 🧱 Passives (R, C, L, D) | Support the boost converter & latch stages |
flowchart LR
A["🔘 Push Button"] --> B["🔒 Soft Power Latch\n(IRLML6401 + MMBT3904)"]
B --> C["🔺 MCP16251\nBoost Converter"]
C --> D["🧠 ESP32"]
D -->|"I²C"| E["📈 ADS1115 ADC"]
E -->|"Analog In"| F["🌫️ Air Quality Sensor\n(via JST)"]
D -->|"GPIO Latch Hold"| B
- Power On → Button press pulls the MOSFET gate low, connecting the battery to the boost converter.
- Latch Hold → ESP32 immediately asserts a GPIO to keep power on, independent of the button.
- Regulate → MCP16251 boosts the battery voltage to a stable rail for ESP32 & peripherals.
- Sense → ADS1115 digitizes the analog sensor signal and streams data over I²C.
- Power Off → ESP32 releases the latch signal on shutdown, cutting battery current to near-zero.
📦 esp32-air-quality-monitor
┣ 📂 images/ → PCB renders, layout & schematic screenshots
┣ 📂 esim/ → eSim schematic & simulation project files
┣ 📂 kicad/ → KiCad schematic + PCB layout files
┣ 📄 README.md → You are here 👋
┗ 📄 Synopsis.docx / .pdf → FOSSEE Research Migration Project synopsis
| Condition | Expected Output |
|---|---|
| Battery = 3.7 V | Regulated Boost Output ≈ 5.0 V |
| Sensor Input = 1.65 V | ADS1115 Output ≈ Mid-scale digital code |
| Latch Released | Battery draw → ≈ 0 mA (standby) |
AQuality32: A low-cost, open-source air quality monitoring device leveraging the ESP32 and google platform Daniel M. Pineda-Tobón, Albeiro Espinosa-Bedoya, Jhon W. Branch-Bedoya — HardwareX, Vol. 21, Article e00607 (2024) 🔗 ScienceDirect / HardwareX
Built by Haridharan D Department of Electronics Engineering (VLSI Design & Technology) Chennai Institute of Technology, Chennai, Tamil Nadu, India
🔬 Part of the FOSSEE Research Migration Project, IIT Bombay 🌐 esim.fossee.in/research-migration-project
