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Reading this thread I found out that you can power on the rpi from idle by connecting gpio3 (pin5 revB) to ground, tested it and it works great.

I didn't read that anywhere else, including in the basic or detailed gpio documentations so i was wondering where it was documented.

And if it's actually undocumented, if there's a source for undocumented gpio features on the rpi?

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So far I only knew you could power it on from idle using the unpopulated reset pins but as it acts as a true reset switch and I don't want to use that as a power button.

Well I now have an onboard power button, with the help of a shutdown pyhton script which I was already using, fantastic.

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eldon
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2 Answers2

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It's called "wake from halt". Some info can be found at here. This feature is implemented in the bootloader.

Ghanima
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Gerben
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  • Does this still work on RPi 4? Or is it now done using the `GLOBAL_EN` connect on the PWA? – Seamus Sep 18 '20 at 08:34
  • @Seamus yes, it works on a RPi 4, so you can continue to use it, or use `GLOBAL_EN` instead if you prefer. The same (or another) pin can be configured with a device-tree overlay to also shut down on the same kind of signal, which I prefer to `GLOBAL_EN` because it allows the kernel to shut down safely. – davidA Nov 08 '20 at 22:11
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When the pi is halted using sudo halt or similar, pulling pin 5 low will make it boot up again. https://raspberrypi.stackexchange.com/a/19754/8697

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Milliways
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