I have created a PCB to simplify a basic encoder Zynthian build.
It is centered around an MCP23017 IO expander, with the pinout headers configured for use with “off the shelf” 5-pin arduino style encoders. The hope here is that this will fill the gap for some of the other DIY builders that want to get started with their first Zynthian.
It also includes nice to have, but optional extras. A 2pin header output for driving a 7" Pi Foundation touchscreen, a 5V power input to simplify using a high current supply, and a GPIO-PWM modulated 5v fan output for cooling a Pi4.
I have included Pi zero style mounting holes so that an Audioinjector zero can be used as the soundcard and mechanically secured to the full assembly if desired. The build is intended to be a Pi stack, using 40pin stacking headers, and no ribbon cable.
At this point, the design is “experimental” and I am waiting to send it off for prototyping and SMT assembly. Unsure at this point when I’ll be able to prove out the design, I’m expecting it will be at least June at this point.
All files are in a forked zynthain-hw repo:
This is my first go at hardware design. Comments, criticism and suggestions are welcome.