Hi, I want to start an RPi from halt state, when a PIN of my 5V Arduino goes high (I might want to add a switch based solely on the power supply of the Arduino, so I try to avoid solutins that work differently). I also want to read if that pin is high while the Pi is running.
The Pi starts from halt if I connect GPIO3 to GND.
I think I got it, but just to confirm, is the attached plan (aside from a solution with optoisolators) how I safely do it? I am not quite sure if R3 is necessary. I guess in the halt state, the internal pull-up is activiated, but as far as I read, that is not necessarily the case in th running state. Any Pi experts here?
Does anybody strongly suggest optoisolators?
EDIT: Just noticed that values of R1 and R2 are switched.
EDIT2: ... and collector and emitter of the transistor have to be switched