I recently completed a project to build a "hat" pcb for the Raspberry Pi 3 to drive a Moonlite focuser via the PI's GPIO pins and a DRV8805 controller. As I use Ekos/INDI for my imaging I also wrote a new focuser driver for it.

On the off chance this is of any use to anyone else the hardware is available under the CERN OHL and the driver is available under the GPL3.

There's more information about the project on my website along with links at the bottom of the page to several blog posts that cover the issues I encountered during the project and mistakes made (quite a few ).

If you just want to see the driver it's on bitbucket in the indi_driver/indi-mupastrocat/ directory. Note: Develop branch has the latest code, just needs a little more testing before it's merged into master again. Few more changes to make such as temperature compensation and also reducing the indi message spam during focusing.

Sadly there's only been one night of clear skies since finishing the project, so whilst I managed to test the focuser out and know everything works, I've yet to get time to take any images with it Fingers crossed this month is better than December was.

Lovely project especially since it's both open hardware + open software. I recently grew quite interested in the open hardware world as world and started using KiCAD to examine several board designs. Glad you have everything in KiCAD as well plus all the issues you encountered. Very well documented! I might compile an article for the main website in a day or two for this project, will let you know if I need any addition information.