It may be possible to implement a software solution to wake up the Pi but I don't know how to do it.
Suggestion is GPIO3 can be used.
There's nothing to build here, but we need to understand how to wake up the Pi from a halt state before we build the shutdown functionality. Simply put, shorting pins 5 and 6 (GPIO3 and GND) together will wake the Pi up from a halt state.
An easy way to test this is to shutdown the Pi with sudo shutdown -h now, and connect pins 5 and 6 with a female to female cable. You only need to short them momentarily. Then you should find that the Pi is "awake".
With the UPS-Lite Hat we are able to use GPIO4 to detect that external power has been disconnected and use the UPS power to run the Pi while a halt command is issued. The question is how to use the reconnection of external power to trigger the wake up. When GPIO4 goes Hi with external power connected can we connect GPIO3 to GND and then release it after a second. What circuit could achieve this?
It may be possible to implement a software solution to wake up the Pi but I don't know how to do it.
Suggestion is GPIO3 can be used.
There's nothing to build here, but we need to understand how to wake up the Pi from a halt state before we build the shutdown functionality. Simply put, shorting pins 5 and 6 (GPIO3 and GND) together will wake the Pi up from a halt state.
An easy way to test this is to shutdown the Pi with
sudo shutdown -h now, and connect pins 5 and 6 with a female to female cable. You only need to short them momentarily. Then you should find that the Pi is "awake".With the UPS-Lite Hat we are able to use GPIO4 to detect that external power has been disconnected and use the UPS power to run the Pi while a
haltcommand is issued. The question is how to use the reconnection of external power to trigger the wake up. When GPIO4 goes Hi with external power connected can we connect GPIO3 to GND and then release it after a second. What circuit could achieve this?see
GPIO-shutdownin/boot/overlays/README