Hiya!

I started an open source project for building a Raspberry Pico (microcontroller) based stand-alone USB to Serial mouse adapter already back in May. I posted about it on the Release Announcements (amouse - USB to Serial Mouse adaptor (Raspberry Pico/Linux)) and it was suggested I might want to have a topic here as well for more visibility, and in hopes it might be useful for others too. The software also runs on a Raspberry Pi or other Linux-based systems with a built-in or add-on USB serial port. The aim has been to build an adapter that requires only a few components and relatively little in electronics complexity, providing a convenient software-based interface for configurability with some good documentation.

Suggestions and comments welcome!

The firmware and the software can be found here: https://github.com/Aviancer/amouse
Direct link to pre-built firmwares: https://github.com/Aviancer/amouse/releases

We're up to version (as of 26.12.2021):
Pico 1.3.0
Linux 1.3.0

Current features include:
- Runs on Raspberry Pico and Linux
- Emulation for Microsoft wheeled mouse (3 buttons)
- Emulation for Microsoft 2-button mice
- On-the-fly sensitivity adjustment (mouse button + wheel combination on the USB side)
- Serial Console for configuration
- Swapping left/right mouse buttons

Video of the serial console feature: https://www.youtube.com/watch?v=DIYM_tL-Ly4

WIP/Planned:
- Saving settings to non-volatile memory
- DOS-based software for changing settings
- Emulation for Microsoft 3-button mice (no wheel)
- Emulation for Logitech 3-button mice
- Build-time configurable GPIO pins (Supporting more hardware designs)
- PCB for the adapter

I've drawn up a schematic for building the adapter, a PCB design is in the plans. An alternative schematic with a male serial port also exists. The MAX3232 chip can also be replaced with a off-the-shelf 2-in 2-out RS232 board for a very simple build. All the schematics are also "open" for use.

It's been a real fun learning experience building this so far! Not to mention useful since I've been making some good use of it myself.