Firmware Fun

Overview

Firmware Fun is an embedded firmware project designed for the ESP32-S3 microcontroller. The firmware provides functionality for:

• Thermocouple temperature sensing: Reads data from multiple MAX31856 thermocouple amplifiers.
• WiFi provisioning: Allows the device to connect to WiFi networks via a captive portal.
• Over-the-Air (OTA) firmware updates: Securely downloads and verifies firmware updates from GitHub releases.
• Web Serial API communication: Enables communication with the device via a browser-based serial interface.
• JSON-based command protocol: Processes commands sent to the device in JSON format.
• Status LEDs: Provides visual feedback for connection and data transmission states.

Features

1. Thermocouple Reading

• Uses the Adafruit MAX31856 library to interface with up to 4 thermocouple channels.
• Reads and transmits temperature data at a configurable sampling rate.

2. WiFi Provisioning

• Implements a captive portal for easy WiFi setup.
• Supports both Access Point (AP) mode and Station (STA) mode.
• Monitors WiFi connection status and reconnects if disconnected.

3. OTA Firmware Updates

• Downloads firmware updates from GitHub releases.
• Verifies firmware integrity using RSA PKCS#1 v1.5 signature verification with SHA256.
• Streams firmware to flash memory to avoid RAM exhaustion.

4. Web Serial Communication

• Implements a JSON-based protocol for sending and receiving commands via the Web Serial API.
• Provides real-time temperature data and device status.

5. Status LEDs

• Blue LED indicates WiFi connection status.
• Yellow LED indicates data transmission activity.

Repository Structure

The repository is organized as follows:

firmware-fun/
├── src/
│   ├── main.cpp                # Entry point of the firmware
│   ├── config.h                # Configuration constants (extern declarations)
│   ├── config.cpp              # Configuration constants (definitions)
│   ├── wifi/                   # WiFi-related functionality
│   │   ├── wifi_manager.h      # WiFi manager header
│   │   └── wifi_manager.cpp    # WiFi manager implementation
│   ├── ota/                    # OTA update functionality
│   │   ├── ota_update.h        # OTA update header
│   │   └── ota_update.cpp      # OTA update implementation
│   ├── sensors/                # Sensor-related functionality
│   │   ├── thermocouple.h      # Thermocouple header
│   │   └── thermocouple.cpp    # Thermocouple implementation
│   ├── web/                    # Web server and captive portal
│   │   ├── setup_portal_html.h # HTML for the captive portal
│   │   └── web_server.cpp      # Web server implementation
│   ├── utils/                  # Utility headers
│   │   ├── connection_state.h  # Connection state enum
│   │   └── helpers.h           # Miscellaneous helper functions
├── platformio.ini              # PlatformIO project configuration
├── SETUP.md                    # Setup instructions for the project
├── CONTRIBUTING.md             # Contribution guidelines
├── boards/                     # Board-specific configuration files
│   └── esp32-s3-devkitc-1-n16r8.json
├── data/                       # Data files (e.g., SPIFFS)
│   └── default_16MB.csv
└── README.md                   # Project documentation (this file)

Key Components

1. main.cpp

• Orchestrates the firmware's functionality.
• Handles setup and loop logic.
• Initializes peripherals, WiFi, and OTA updates.

2. config.h and config.cpp

• Centralized configuration constants.
• config.h declares extern constants, and config.cpp defines them.

3. WiFi Manager

• Located in src/wifi/.
• Handles WiFi connection, AP mode, and captive portal.

4. OTA Updates

• Located in src/ota/.
• Implements secure OTA updates with signature verification.

5. Thermocouple Reading

• Located in src/sensors/.
• Interfaces with MAX31856 thermocouple amplifiers.

6. Web Server

• Located in src/web/.
• Hosts the captive portal for WiFi provisioning.

7. Utilities

• Located in src/utils/.
• Includes shared enums and helper functions.

Build and Upload

This project uses PlatformIO for building and uploading firmware.

Prerequisites

• Install PlatformIO.
• Ensure the ESP32-S3 board is connected to your computer.

Build

Run the following command in the project root:

pio run

Upload

To upload the firmware to the ESP32-S3, run:

pio run --target upload

Monitor

To monitor the serial output, run:

pio device monitor

OTA Update Process

1. The device checks for updates at regular intervals (default: every 6 hours).
2. It downloads the latest firmware from the GitHub releases API.
3. The firmware is verified using RSA signature verification.
4. If valid, the firmware is flashed, and the device reboots.

Contribution

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

License

This project is licensed under the MIT License. See LICENSE for details.

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Happy coding!