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ESP32-S3 Camera Firmware

This firmware is designed for the Seeed Studio XIAO ESP32-S3 development board using the Espressif ESP32 Arduino Core 2.0.17.

Hardware Specifications

The firmware leverages the XIAO ESP32-S3's capabilities:

  • Processor: ESP32-S3R8 dual-core @ 240MHz
  • Memory: 8MB PSRAM + 8MB Flash
  • Connectivity: Wi-Fi 2.4GHz + Bluetooth 5.0 LE
  • GPIO: 11 digital pins with ADC, PWM, I2C, SPI, UART support

Using arduino-cli

Install the board

arduino-cli config add board_manager.additional_urls https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
arduino-cli core install esp32:esp32@2.0.17

ESP32 Arduino Core 2.0.17 Features

This firmware is tested with ESP32 Arduino Core 2.0.17, which includes:

  • Improved BLE stability and performance
  • Better camera support for ESP32-S3
  • Enhanced power management
  • Optimized PSRAM usage
  • Bug fixes for I2S audio processing

Get board details

On Windows 11 board should be showing as esp32:esp32:XIAO_ESP32S3 but instead might show as esp32:esp32:nora_w10, esp32:esp32:wifiduino32c3, or something else.

arduino-cli board list
arduino-cli board details -b esp32:esp32:XIAO_ESP32S3

Compile and upload

Change COM5 to the port name from the board list output

arduino-cli compile --build-path ../build --output-dir ../dist -e -u -p COM5 -b esp32:esp32:XIAO_ESP32S3:PSRAM=opi

Opus support

Go to your Arduino libraries folder.

You can get the libraries folder location with the following command:

arduino-cli config get directories.user

Note: You have to add /libraries to the path to get the libraries folder.

Then clone the two libraries needed to add Opus support:

git clone https://github.com/pschatzmann/arduino-libopus.git
git clone https://github.com/pschatzmann/arduino-audio-tools.git

Hardware Constants

The firmware uses centralized hardware constants defined in xiao_esp32s3_constants.h:

Key Constants Used:

  • GPIO Pins: All pin definitions use named constants (e.g., XIAO_ESP32S3_PIN_A0)
  • ADC Configuration: 12-bit resolution, 3.3V reference
  • Memory: 8MB Flash, 8MB PSRAM specifications
  • Power: Operating voltages and current consumption limits
  • Camera: GPIO pin mappings for OV2640/OV5640 sensor
  • Audio: I2S pin configurations for microphone

Pin Mappings:

  • A0 (GPIO2): Battery voltage sensing
  • A1 (GPIO3): USB power detection
  • GPIO41/42: I2S microphone (SCK/WS)
  • GPIO10: Camera XCLK
  • GPIO40/39: Camera I2C (SDA/SCL)
  • GPIO13-18, 38, 47-48: Camera data and control pins

Battery Detection

The firmware includes automatic lithium battery detection functionality to ensure the device is properly powered and can report accurate battery status.

How it works

The system uses ADC pin A0 to read the battery voltage and determine if a lithium battery is connected:

  • Voltage Range: Detects batteries between 3.0V - 4.3V
  • Sampling: Takes 10 samples and averages them for accuracy
  • Status Reporting: Updates device status via BLE when battery state changes

Device Status Values

The device reports battery status through the Device Status BLE characteristic:

  • 0x03 (READY) - Battery detected and device ready
  • 0x08 (BATTERY_NOT_DETECTED) - No battery detected or voltage out of range

Battery Level Calculation

When a battery is detected, the firmware estimates the charge level based on a typical Li-ion discharge curve:

  • 4.15V+: 95-100% charge
  • 4.0V-4.15V: 75-95% charge
  • 3.8V-4.0V: 50-75% charge
  • 3.6V-3.8V: 25-50% charge
  • 3.4V-3.6V: 10-25% charge
  • 3.2V-3.4V: 5-10% charge
  • 3.0V-3.2V: 0-5% charge

Calibration

The voltage divider ratio may need adjustment based on your specific hardware. Check the serial output for debugging information:

ADC raw: 2048, ADC voltage: 1.65V, Battery voltage: 3.30V

If the battery voltage reading doesn't match your multimeter reading:

  • Too high: Decrease BATTERY_VOLTAGE_DIVIDER in constants.h
  • Too low: Increase BATTERY_VOLTAGE_DIVIDER in constants.h

Testing Battery Detection

Use the included test script to verify battery detection:

python3 test_battery_detection.py

This script will:

  1. Scan for OpenGlass devices
  2. Connect via BLE
  3. Monitor device status and battery level
  4. Report when battery is connected/disconnected

Hardware Notes

  • The XIAO ESP32S3 Sense can be powered via USB or battery
  • Battery detection works by measuring voltage on the ADC pin
  • If no battery is detected, the device will still function on USB power
  • Battery detection is checked during startup and periodically during operation

Charging Detection

The firmware includes USB charging detection to monitor power source:

Circuit Requirements:

  • 5V pin → 100kΩ resistor → A1 pin → 47kΩ resistor → GND
  • This creates a voltage divider: 5V × (47kΩ / 147kΩ) ≈ 1.6V

Status Indicators:

  • 0x09 (CHARGING) - USB power detected with battery voltage > 4.1V
  • 0x0A (BATTERY_UNSTABLE) - Connection issues detected

The system monitors for:

  • USB power presence via voltage divider
  • Battery voltage stability over time
  • Rapid voltage changes indicating connection issues

TODO: HAL - Additional Interfaces: e-ink, LED(s) - Sensors - Haptic - Storage/Memory

FIRMWARE
    - BLE Mesh
    - Toggle-able features
    - ML Battery Optimization
    - Hotspot Security
    - BLE Security

USE CASES:
- ML TRAININD DATA COLLECTIONS
- ROBOTICS
- CAD
- 3D SCANNING
- Agriculture
- Space Tech
- ACCELERATION