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.

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

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

Clone the repository:

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

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

Press F7 or Ctrl+Shift+B to build.
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.

Create and activate a Python virtual environment:

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

Install pymcuprog inside the environment:
```
 pip install pymcuprog
```
Verify installation:
```
 pymcuprog --version
```

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.

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