On Off Shim with Zero Lipo


#1

I would to use a Pi Zero W with Zero LiPo to make a portable message board / badge using ScrollPhatHD but would like to be able to soft shutdown the system a) because it’s a lipo and shouldn’t be run flat and b) because I don’t like sorting out corrupted files caused by hard shutdowns. The OnOff Shim uses the same pins as ZeroLiPo and so I am thinking that it won’t work or could be dangerous. Thoughts on this would be welcome


#2

Zero LiPo will assert BCM 4 when the battery starts to run low- you can use this to trigger a soft shutdown, there’s no need for OnOff SHIM.

OnOff SHIM is designed to cut the power from an external microUSB supply, and wouldn’t bring much to the table in this case.

After soft-shutdown your Pi will fire up again when you reconnect your charged battery.

Our Clean Shutdown script supports Zero LiPo: https://github.com/pimoroni/clean-shutdown

This is set up automatically when you install Zero LiPo via: curl https://get.pimoroni.com/zerolipo | bash


#3

Thanks for this as has been while since I looked at the LiPo details and forgot about the soft shutdown. I missed making a point of the need to shutdown the Pi at will as the ScrollPhatHD is so bright you wouldn’t really want it on the whole time…
At home I can access the Pi via SSH or VNC if running the full version so shutting down is easy but am thinking of using this out “in the field” so need another way to do this.


#4

Since the “Low Battery” warning doesn’t do anything more complicated than pull GPIO #4 low, you could wire a regular push button between GPIO #4 and Ground (conveniently located right next to each other). Pushing down that button would initiate exactly the same soft shutdown procedure as the low battery warning.


#5

Amazing as always and thank you