Firmware and CLI for uploading GBA multiboot ROMs using a Raspberry Pi Pico or other RP2040-based board.

Flash your pico with the multiboot firmware, see the latest release for prebuilt .uf2 files for common RP2040 boards.

Install the multiboot CLI:

pipx install multiboot

Run the multiboot CLI, specifying the path to your GBA multiboot ROM:

multiboot path/to/your/game.mb

You can also specify the serial port and timeout if needed:

multiboot path/to/your/game.mb --port /dev/ttyUSB0 --timeout 20

You'll need a sacrificial link cable, I recommend using a Gameboy Color link cable since the aftermarket versions typically have all pins connected.

Aftermarket cables all have wildly different internal wire colors, so you'll need to use a multimeter to figure out which wire goes to which pin.

The pinout for the male connector is as follows (when looking at the connector):

 ___ _____________ ____| |____ / \ / \ | VCC SI SC | | VCC SI SC | | SO SD GND | | SO SD GND | |_______________| \_______________/ GBC Cable GBA Cable 

The firmware uses the default SPI peripheral and pins for the configured board. For the Raspberry Pi Pico and Seeed XIAO RP2040, the pin mapping is as follows:

Check the Pico SDK boards files for the pin mappings for your board.

This project is licensed under the MIT License. See cli/LICENSE and firmware/LICENSE for more details.

Upload CLI is based on jojolebarjos' excellent gba-multiboot upload script.