The story of a community sourced external flash modification to include hundreds of games on the Arduboy. The project was started by the Arduboy community user by the name of Mr. Blinky. Mr. Blinky created a custom bootloader and external cartridge for the Arduboy that will interface with a Winbond W25Q SPI flash module and also the OLED Display to allow the user to select from games stored on the external flash. The bootloader named "Cathy3k" will automatically reprogram the application code and start the game.

This was an incredible development for the community and soon users such as serisman were doing "deadbug" style modifications to their Arduboy, soldering the flash chip directly to the back of the Arduboy. This gave me the idea of using a flexible PCB to mount the components to the back of the Arduboy. The first test PCB that I made worked perfectly, but there were still some changes. You still needed to use an external programmer to update the 32u4 to have the new Cathy3k bootloader. It was decided to add an ATTiny85 processor to both store and provide the new bootloader so that a user can automatically update their firmware by holding the reset button.

The members of the Arduboy community were encouraged to draw digital graffiti that would translate to the rear silk screen of the Mod Chip:

Another update that was made in before production was to make a cutout to fit behind the speaker, and make it easier to install without interfering with the wires. 

To produce the final product, PCBway assembly service was chosen. Already it was a good choice because of the many options for color and thicknesses, but they assigned a sales manager who has been helping the whole time to make the process easier when I was still developing the panel for production. If you have a lot of flexible circuit assembly to get done it's worth checking them out if you don't use their services already.

You can make your own mod chip with the schematics included here and also on the Arduboy Community, but if you'd like to purchase a pre-programmed mod chip head over to the Arduboy store!