That requires software, I need detecting on hardware level that doesn't require any specific software running on the device that is being checked.
Are you willing to make a minor change to its config.txt and do you have any of the possible UART pins free?
If so, enable one of the UARTs (see /boot/overlays/README) and have the other Pi monitor the UART's TX pin. As long as you don't run a getty on it it will go high once activated (TTL serial is active low) and low on shutdown.
What it won't let you do is distingush between a active Pi and one where the kernel paniced or the OS has hung in some other way.
Statistics: Posted by thagrol — Sun Sep 01, 2024 11:33 pm