lezyne-rear-light-firmware

Open firmware for Lezyne bike rear lights based on ATTINY202

This repository contains a minimal firmware as a C project for the ATtiny202 microcontroller using GCC, CMake, and VS Code. It also includes instructions for programming the chip using an FT232 USB-UART adapter via the UPDI interface with pymcuprog.

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Table of Contents

• Dependencies
• Setup Build Environment
• Building the Project
• Flashing the Firmware
• Reading Flash Content
• Hardware Setup
• License

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Dependencies

Ensure the following tools are installed on your system:

• GCC AVR toolchain (supports ATtiny 0/1-series)

  sudo zypper install avr-gcc avr-libc
  

• CMake

    sudo zypper install cmake
  

• Python 3, pip and venv

    sudo zypper install python3 python3-pip python3-venv
  

• VS Code (optional but recommended)
• CMake Tools extension for VS Code

Setup Build Environment

1. Clone the repository:

    git clone https://git.mosad.xyz/localhorst/lezyne-rear-light-firmware
    cd lezyne-rear-light-firmware
   

2. Configure the CMake project:
   • Open the folder in VS Code.
   • Select the AVR-GCC kit in the bottom blue bar.
   • Run CMake: Configure (from command palette) if it doesn't auto-run.

Building the Project

1. Press F7 or Ctrl+Shift+B to build.
2. Output files are generated in the 'build/' folder:

• main.elf → ELF executable
• main.hex → HEX file (flashable)
• main.bin → BIN file

Flashing the Firmware

Hardware: FT232 USB-UART adapter connected to UPDI with a 4.7 kΩ resistor.

1. Create and activate a Python virtual environment:

    python3 -m venv pyupdi-env
    source pyupdi-env/bin/activate
   

2. Install pymcuprog inside the environment:

    pip install pymcuprog
   

3. Verify installation:

    pymcuprog --version
   

4. Flash using pymcuprog:

    pymcuprog -t uart -u /dev/ttyUSB0 -d attiny202 write -f build/main.hex
   

Hardware Setup (FT232 → ATtiny202 UPDI)

 FT232 TX ----[4.7kΩ]---- UPDI (pin 6)
 FT232 GND --------------- GND
 VCC -------------------- VCC (3.3V or 5V, must match FT232 logic)

License

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