Hello! I am using a raspberry pi zero 2 w for a camera project, and i wanted to use the witty pi 4 mini to turn the pi on an off on a timer. My build also includes a Clipper LTE breakout board (from SP/CE) which communicates with the Pi over UART on GPIO 14 (TXD) and GPIO 15 (RXD). I understand that WittyPi 4 Mini monitors GPIO 14 (TXD) to detect when the Pi has shut down, so it knows when to cut power.
Since the Clipper LTE is actively using that same pin for UART communication, I'm concerned this will either:
- Prevent WittyPi from cutting power correctly after shutdown, or
- Cause WittyPi to cut power unexpectedly while the Pi is still running
I also understand that on the Pi Zero 2 W, hardware UART is only available on GPIO 14/15, so remapping to different pins isn't straightforward.
Is there a known workaround for this conflict? Would the WittyPi 4 Mini still work reliably in this setup, or would you recommend a different approach?
Thank you!!
This use case has actually been tested before, active UART communication will not be detected as system on/off. The TXD goes through a diode and then has a big capacitor to the ground, and Witty Pi 4 is monitoring the voltage on that capacitor. Occationally pulling down TXD will not be detected by Witty Pi 4.