Beginners • Re: RPI for ATX PSU power status sense wiring question

Basically, I need to know if just connecting the 3.3v PSU line to a GPIO pin through a 10K Ohm resistor will do the job or if I need to do anything else or differently.

I believe you're reading things incorrectly.

If all you need to do is sense whether the ATX PSU is on you need to connect two wires:

1. The PSU's output ground to one of the Pi's ground pins.
2. The PSU's 3.3v line to a GPIO input pin.

You'd then either enabled the interal pull down on your chosen GPIO or, as shown in the diagram use an external 10K pulldown resistor on the same GPIO. A pull down is required to avoid the input floating (and therefore giving inaccurate results) when the ATX PSU is off.

The relevant part of the diagram is that connected to GPIO 25 and ground. You can ignore everything connected to GPIOs 23 and 24 unless you want to control the PC's power and reset buttons.

Two further things to be aware of:

1. This will tell you if the PSU is on. It will not tell you anything about the state of the OS on said PC.
2. All risks are yours. I cannot and will not accept any liability for loss or damage caused by you implimenting this.

Statistics: Posted by thagrol — Sat May 11, 2024 10:36 am

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