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Configurable shutdown period? - Printable Version

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Configurable shutdown period? - mentalinc - 03-15-2019

Is it possible to have the shutdown delayed for a user set period i.e. and hour?



Like this:

https://youtu.be/vMvMXd4RvdA?t=1109



In short, turn off the ignition, the pi turns the display off but keeps running for an hour and if the ignition isn't turned back on it turns off.

If the ignition is turned on the screen comes on and you're already booted so its an "instant on". great for quick stops like the gas station or popping into the shops.



Thoughts or guidance on how to make this possible?



Re: Configurable shutdown period? - BlueWave - 03-16-2019

Sure it is possible. You can either write your own service similar to our for BWS CAR PS (and turn off our), or you can modify current script for shutdown according to your requirements.


Re: Configurable shutdown period? - Hisma - 03-31-2019

As mentioned the PW Car PS works fine, as does other variants like the mausberry. I am the person that did the video you linked, and here's a video that explains in more detail what I did (if you didn't find this video yet) -

https://www.youtube.com/watch?v=rknBevexOcU



Re: Configurable shutdown period? - mentalinc - 04-17-2019

Thanks @Hisma



Can you please explain what the relay is for between the timer and the GPIO pin?

Can we not just use a step down from 12v to 3.3v something like a LM2596 for example?



Re: Configurable shutdown period? - Hisma - 04-18-2019

As you stated, the relay is simply acting as an interposing relay to isolate the 12V from the GPIO voltage. You can accomplish the same thing by stepping down the voltage, sure. In my case, I already had a relay board in my car as I was using it to trigger my backup cam etc, so it made sense to re-use it.


Re: Configurable shutdown period? - mentalinc - 04-27-2019

I assume for the reverse cam you just hooked up the 12v fromt he reverse bulb and ran in through the relay..

Did you need to change the amps at all or is the drop to below 3.3v enough (but closer to 3.3 than 0v) enough?

I.e. do I need to play with resistors to change amps etc?, I can't see anyone saying they needed resistors..



Re: Configurable shutdown period? - Hisma - 04-28-2019

You don't need any additional resistors. With a standard 12V relay board, you just feed the 12V signal from the camera on the input side of the relay, and on the output side, you take 1 wire to 3.3V on the pi, and another wire to a gpio pin.

You can do the exact same thing with a 12V ignition trigger wire. Ignition on = relay on. Ignition off = relay off, script starts shutdown timer.