2021-04-01, 07:08 PM
I have developed a solid-state power-up/down system. It uses grounding GPIO3 to initiate shutdown (see https://www.stderr.nl/Blog/Hardware/Rasp...utton.html for description and necessary line in config.txt) and TP4 to supply 3V3 while the Pi 4B is running. I had to do some searching to find a connection that is high whenever the Pi is active but goes low when the Pi stops. Even that line takes a few seconds to go high at startup and goes low for a few seconds while loading. Hence the capacitor in the circuit. So it takes a few seconds after the Pi has stopped before the power is cut.
The same momentary switch that initiates the shutdown also starts the Pi by connecting the supply.
The current when off is less than 0.1 microAmp according to my multimeter.
The P MOSFET is good for 27Amp so it could be used to switch a lot of peripherals at the same time.
Derek
The same momentary switch that initiates the shutdown also starts the Pi by connecting the supply.
The current when off is less than 0.1 microAmp according to my multimeter.
The P MOSFET is good for 27Amp so it could be used to switch a lot of peripherals at the same time.
Derek