4 ms·

Most cars don’t supply 12v thorough the accessory outlet when the ignition is off, so you’d need some of backup power source. Pis do not cope well with having t

Most cars don’t supply 12v thorough the accessory outlet when the ignition is off, so you’d need some of backup power source. Pis do not cope well with having the power cut off abruptly, so unless you want to carry a spare microSD card around at all times, you’d need some kind of solution for handling shutdowns.

woolvalley 9y ago
A battery and something that detects the power has been cut off and does a shut down/standby. Rpi startup takes a little while, so I don't know how nice it would be to wait 1 minute for your android auto system to startup.
- thr0awaz 9y ago
  It's not a big job to wire the detector you're talking about in your first sentence - it's more or less a relay and a capacitor (albeit a big capacitor, or maybe a battery if you put some more wiring and a charger in the circuit) For the second one... you'd need to maybe consider tapping into the CAN bus and listening for a door unlock event, then powering up off that, and/or stripping everything out of the kernel and services that isn't needed... you could probably get that boot down to 10-15 seconds
  - bigiain 9y ago
    Pretty sure he's already done that second part. The linked "features demo" video on youtube shows it booting into the Crankshaft app from power on (through Rasbian Lite) in ~11 seconds. https://www.youtube.com/watch?v=tFEpfuDBDjM&feature=youtu.be https://www.youtube.com/watch?v=tFEpfuDBDjM&feature=youtu.be
- rkangel 9y ago
  If you watch the video, the bootup time of the distro involved is significantly less than one minute - more like 10 seconds in fact.
the-dude 9y ago
> Pis do not cope well with having the power cut off abruptly Even with noatime?
- Piskvorrr 9y ago
  Even with the card mounted readonly. (Source: recent experience)
TickleSteve 9y ago
That problem is simply because you're writing to the card continuously. Make your distro run from RAM and you're fine... that is what most embedded devices do, stick it all in an initramfs.
askvictor 9y ago
I was quite surprised that my 2010 car does provide power through that outlet when it's off. What's your basis for saying _most_? I only have two datapoints myself, so can't generalise.
- IshKebab 9y ago
  Mine too, from 2003. Stupid design, even then.
- jackfraser 9y ago
  That's surprising. Seems like it would be easy to inadvertently drain your battery.

woolvalley 9y ago

A battery and something that detects the power has been cut off and does a shut down/standby. Rpi startup takes a little while, so I don't know how nice it would be to wait 1 minute for your android auto system to startup.

thr0awaz 9y ago
It's not a big job to wire the detector you're talking about in your first sentence - it's more or less a relay and a capacitor (albeit a big capacitor, or maybe a battery if you put some more wiring and a charger in the circuit) For the second one... you'd need to maybe consider tapping into the CAN bus and listening for a door unlock event, then powering up off that, and/or stripping everything out of the kernel and services that isn't needed... you could probably get that boot down to 10-15 seconds
- bigiain 9y ago
  Pretty sure he's already done that second part. The linked "features demo" video on youtube shows it booting into the Crankshaft app from power on (through Rasbian Lite) in ~11 seconds. https://www.youtube.com/watch?v=tFEpfuDBDjM&feature=youtu.be https://www.youtube.com/watch?v=tFEpfuDBDjM&feature=youtu.be
rkangel 9y ago
If you watch the video, the bootup time of the distro involved is significantly less than one minute - more like 10 seconds in fact.

the-dude 9y ago

> Pis do not cope well with having the power cut off abruptly Even with noatime?

Piskvorrr 9y ago
Even with the card mounted readonly. (Source: recent experience)

TickleSteve 9y ago

That problem is simply because you're writing to the card continuously. Make your distro run from RAM and you're fine... that is what most embedded devices do, stick it all in an initramfs.

askvictor 9y ago

I was quite surprised that my 2010 car does provide power through that outlet when it's off. What's your basis for saying _most_? I only have two datapoints myself, so can't generalise.

IshKebab 9y ago
Mine too, from 2003. Stupid design, even then.
jackfraser 9y ago
That's surprising. Seems like it would be easy to inadvertently drain your battery.