Esp32-sensor board

ESP32-C3 IoT Sensor Board

A 4-layer IoT development board built around the ESP32-C3-WROOM-02 module, featuring onboard environmental sensing, an SD card socket, USB-C programming, and LiPo battery power management. Designed entirely in KiCad 10 (schematic + PCB layout).

Overview

This project is a custom IoT development board designed as a learning exercise in professional 4-layer PCB design with KiCad. It combines a Wi-Fi/BLE microcontroller, a small set of environmental sensors, onboard SD and flash storage, and a complete USB-C + LiPo power path into a single compact board.

Key Features

• Microcontroller: ESP32-C3-WROOM-02-H4 module (RISC-V, Wi-Fi + Bluetooth LE)
• USB-C connectivity: shielded USB-C receptacle with a CP2102N USB-to-UART bridge for programming and serial communication, plus USB ESD protection and an auto-program (auto reset/bootloader) circuit
• Battery power management: JST-PH LiPo connector, MCP73871 battery charger with USB/battery power-path management, and charging/charged/power-good status LEDs
• Onboard regulation: LM1117 3.3 V LDO regulator, resettable PTC fuse, and dedicated power flags/power indicator LED
• Environmental sensing: BME280 sensor (temperature, humidity, and barometric pressure) over I2C
• Ambient light sensing: TEMT6000 phototransistor with analog output
• Sound sensing: MAX4466 electret microphone with adjustable-gain amplifier
• Onboard storage: microSD card socket plus an SPI NOR flash chip (W25Q32, 32 Mbit / 4 MB)
• Expansion headers: I2C header for an external OLED display, plus a breakout header for spare GPIOs
• User interface: Reset and Boot buttons, status LEDs, SPI test points
• Design for manufacturing: 4 mounting holes (2.5 mm), rounded/notched board outline, full 3D component models for realistic rendering

Communication Interfaces

PCB Specifications

Repository Structure

esp32-sensor-board/
├── docs/
│   └── images/                        # Renders and reference images (e.g. 3D view)
└── hardware/
    ├── esp32-sensor-board.kicad_pro    # KiCad project file
    ├── esp32-sensor-board.kicad_sch    # Top-level schematic (power management)
    ├── esp32-c3-02.kicad_sch           # ESP32-C3 module, USB, flash & SD sheet
    ├── sensors.kicad_sch               # BME280, light and sound sensors sheet
    ├── user-interface.kicad_sch        # Buttons, LEDs and expansion headers sheet
    ├── esp32-sensor-board.kicad_pcb    # PCB layout (4-layer)
    └── libraries/                      # Project-specific symbols, footprints & 3D models

Getting Started

1. Install KiCad 10 or later.
2. Clone this repository:

   git clone https://github.com/pasensiojimenez/esp32-sensor-board.git

3. Open hardware/esp32-sensor-board.kicad_pro in KiCad.
4. All custom symbols, footprints, and 3D models are self-contained in hardware/libraries/, so the project should open with libraries already resolved.

Reference & Acknowledgements

This project is based on and follows, as its main reference, the following blog post by Tech Explorations:

• KiCad 9: Designing a 4-Layer IoT Development Board