ChisFlash-MBC5 (GBC Flash Cartridge)

Updated on June 17, 2025: 
The original author has made another re-statement. All the open-source works under his page are welcome for use or sale. It would be best to indicate the source. 
The development process is not easy, and research and development also require purchasing materials. We don't expect huge profits. Just allowing him to gain some popularity would be nice. Thank you for your understanding.

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Currently, most GB flash cartridges are made by disassembling chips from official cartridges, which means one less official cartridge for each disassembly. Although I don't play official cartridges either, I felt a bit heartache seeing this and wondered if I could use a CPLD to replace the MBC chip, which led to this project.

Learned from GitHub that project NekoCart-GB is an open-source MBC5 flash cartridge, which also uses a CPLD chip to replace the MBC5 chip.

So I made the ChisFlash-MBC5 flash cartridge by referring to this project, redrew the board and schematic, used MOSFETs for switching in the dual power supply for save power, and ported and adapted the firmware from the original project.

Features of this card:

1. Replace the genuine MBC5 main controller with a CPLD chip (EPM240), use an 8M flash chip for ROM, and a 128K SRAM chip for RAM, capable of burning a single game up to 8M in size.

2. Supports up to 4-in-1 card combination, with game size being Menu 1M + Game 1M + Game 2M * 3, and save files being 32K * 4. Each save file is independent and will not overwrite each other.

3. The regular version does not use a level conversion chip; the Plus version uses a level conversion chip and is compatible with AP. It is unclear whether the AP handheld supports the regular version. We await a kind soul to conduct a test.

4. The hardware theoretically supports MBC5 games and is compatible with other MBC games. The specific compatibility is unknown, and due to limited personal energy, it has not been fully tested. (Playable Pokémon main series games)

5. In the future, it will support vibration and more card combination sets (pie in the sky)

6. When used in conjunction with the flashcart software "gbcburn" on the NDS, it is possible to flash this card using the NDS without the need to purchase an additional flashcart programmer.

Key points of production:

1. After welding is completed, please measure the voltage from the positive electrode of the battery to one side of the resistor. If the voltage is found to be slowly decreasing or there is no voltage, it indicates poor contact at the bottom of the battery, and a little solder needs to be applied to the bottom to hold the battery in place.

For the 2.plus resistor array, the leftmost one is 30Ω, and the seven on the right are all 470Ω.

3.v1.1 firmware is compatible with hardware v1.1, v1.2, and v1.21, while v1.21 firmware is only applicable to hardware v1.21

Update Log

On October 9, 2024, update the Standard Edition v1.1 and the Enhanced Edition v1.1

On November 28, 2024, update the regular version v1.2 and the enhanced version v1.2; disconnect rst from nor flash and pull it high to enable NDS burning.

On December 19, 2024, the Standard Edition v1.21 was updated to enlarge the battery negative pad; the Enhanced Edition v1.21 added a resistor array compatible pad and enlarged the battery negative pad.

On February 26, 2025, Firmware 1.2 was updated, which supports 3-in-1 (1+2+4), 4-in-1 (1+2+2+2), and single card.

Thanks to the boss of the original project: 和光Channel

Thanks to the boss who provided the NDS flashcart solution: @shn

Linked GBA-sized model miniChisMBC5

ChisFlash is a large-scale open-source replication project related to retro game consoles, aiming to provide affordable and user-friendly hardware solutions for retro game players and resist unscrupulous merchants from exploiting them.

Those interested can search for ChisFlash on the OSHWHUB. Currently, there are already projects such as GBA/GBC flash cartridges, GBASP original PCB, GBA lithium battery modules, etc.