hackinvent / stm32f_gbcart

Game Boy Cartridge emulation from a stm32f4 Development Board

stm32f_GBCart

Game Boy Cartridge emulation from a stm32f4 Development Board

I wrote about this project in my blog:

• https://dhole.github.io/post/gameboy_cartridge_emu_1/
• https://dhole.github.io/post/gameboy_cartridge_emu_2/
• https://dhole.github.io/post/gameboy_custom_logo/

Description

This project implements the emulation of a gameboy cartridge using a stm32f4 Development Board. A real gameboy can be connected to a stm32f4 running this software and load real roms as well as homebrew roms.

• ROM Only and MBC1 Cartridges are implemented. See a full list at:
  • http://www.devrs.com/gb/files/gbmbcsiz.txt
• RAM emulation implemented. The contents will be erased upon powering off the stm32f4
• Custom boot logo implemented. It will be shown only during the first boot.

ROMs

In order to use a rom in the code, the file must be converted into a C array:

cp Tetris.gb rom.gb
xxd -i rom.gb | sed 's/unsigned/unsigned const/g' > tetris_rom.h
rm rom.gb

Files

main.c: Main Program body.

Initialization of the GPIOs.

stm32f4xx_it.c: Interrupt handlers.

The interrupt handler for the rising flag trigger is defined here. It handles the read and write operations of the gameboy to the cartridge.

Custom logo

draw_logo.py: Draws a logo on a window

Requieres pygame

make_logo.py: Converts a png logo image into a binary file to be used as a boot logo

Requieres pygame

./make_logo.py dhole_logo2.png dhole_logo2.bin
cp dhole_logo2.bin logo.bin
xxd -i logo.bin > dhole2_logo.h
rm logo.bin

Issues

If some games don't run, or you get crashes at some points, it may be a timming issue (the timmings are very tight, and I believe they may need to be different on different hardware revisions). You can try goebish's branch which modifies the number of NOPs in the code.