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Hello,

I built a portable xbian system with a Raspberry Pi and 2 screens for in the car. The system is powered by the 12V cigarette lighter socket with a step-down converter to 5V.
In the first version the Rpi was shut down very brutely because the 12V is killed when the car is turned off.
In the second version I put in a small (2200 mAh) powerbank, input is connected to power from the car via the converter, the output powers the Rpi and a USB hub. In that way when the car is powered down, only the screens will turn off, the Rpi can run a few hours on battery power. I can then perform a sudo shutdown -h now.

Now for the question; how can I make a button which switches the Rpi off gracefully? I read somewhere you can connect a button to a gpio pin and GND and when button is pressed a script will perform this command. I can't find it anywhere. And is there a way to switch it back on??

Any help is welcome!

No way to switch back on through GPIO since the device is off.

https://www.pi-supply.com/product/pi-ups-uninterrupted-power-supply-raspberry-pi/

That will work!

Very cool but that price is rediculous, cost as much as the Pi.

(29th Oct, 2014 04:54 PM)f1vefour Wrote: [ -> ]Very cool but that price is rediculous, cost as much as the Pi.

Hey, don't shoot the messenger

It is a good find and I would love to have one myself.

(29th Oct, 2014 09:18 AM)vinz3nt Wrote: [ -> ].... can I make a button which switches the Rpi off gracefully? I read somewhere you can connect a button to a gpio pin and GND and when button is pressed a script will perform this command. I can't find it anywhere. And is there a way to switch it back on??

Any help is welcome!

Yes this would be one way to do it. Another would be to detect when the cars 12V supply stops and use that to initiate a power off script while the pi is still on battery pack power. This way you won't forget to do it!

A simple voltage detector can be bought for less than £1 off ebay and can be connected to the gpio to sense this. There are other ways you could do this too.

The pi would boot up again when the power is restored, or you could use an arduino pro mini and a relay to enable this. They are cheap and easy to program.

skywatch