USB to Atari ST Quadrature Mouse Adapter based upon JJ Michel open source firmware (https://github.com/jjmz/Atari-Quadrature-USB-Mouse-Adapter). This design is mainly THT with the exception of the CH554 SOIC-16 chip.

The CH554 is programmed by first solder bridging the BOOT pads, then plugging it into a computer’s USB port via a double USB-A cord, and then running the Windows WCHISPTool to download and flash the firmware. After successful programming, use copper desoldering braid to remove the boot bridging.

Also works quite well as an Atari 8-bit computer mouse.

Schematics and downloads will be made available at: https://ataribits.weebly.com/