Using Arduino, I'm trying to detect whether Raspberry Pi has successfully turned itself off. I first tried to check on the pins that are used for serial communication between said devices but the pin state is obfuscated by voltage level shifter that protects Rasperry Pi from (eventually accidental) 5V voltage.
So my plan is to set any other Raspberry pin HIGH and hope it will go low as soon as the Arduino shuts itself down.
But I have doubts whether the pin will not lose its state sooner (as soon as my controller application exits, or during the shutdown phase).
So is pin approach a good one if I want to check if the Rasperry Pi is off?