Thinking Aloud: Power Issues for a Raspberry Pi as a Car Computer

We could switch from a Raspberry Pi to an oDroid or another sort of low-power computer-on-a-board. My Pi has a task right now, so if I was to go forward with this, I'll have to get something new anyway, but for sake of this discussion, we'll assume this is it.

I own a USB GPS unit. I own a OBDII-to-USB unit. I own a small VGA monitor for Pi use. A thing that would be useful is a thing that does some networking over the cellphone network, but if it just dumps to my home network when I get home, that'd be good enough.

Here's a niggly bit or me: I start the vehicle and the Pi gets power. I stop the vehicle and the power cuts, leading the computer shutting down suddenly. This is not a happy thing with computers. In fact, I think I can say they hate that, and eventually, the SD card will say enough with this and not boot.

So, the proper solution is to have a power circuit with a battery, that allows it to boot when the car starts and sends the shutdown signal when it stops, but providing enough juice in the battery for the Pi to shut down nicely.

Google told me how to trigger the shutdown when wanted. Just need to figure out how to know what's going on with power.

Making a CarPuter to step into the New Car

It's been a while since I've written on car computing — over two years, it seems — but that doesn't mean I've stopped thinking about it. The top reasons I would've wanted one in years past would've been for Entertainment and Communication, and I think everyone would agree that today, it's far better to just carry a smartphone than to embed one into your car. And, seeing how smartphones are changing so much so fast, doing more than adding the ability to interface with Bluetooth and/or USB to your vehicle seems silly, at least in short-term.

Navigation doesn't fare too much better, so although it's a toss-up whether dedicated units like Garmin and TomTom are better than smartphone navigation like Google Maps, both are accepted as better (more current maps, better interfaces) than in-dash choices.



I think the use that is least considered is recording. Dash cams are common in Russia because they're used for legal protection, but have given YouTube a great catalog of amazing video. I think there's reason beyond "Hold my beer and watch this" for Americans to have dash cams, and I do want one.

But, ultimately, I think the best reason to get into "Carputers" is Diagnostics, getting into the data that is available from your car's OBDII port. The obvious way is to use an OBDII-to-Bluetooth adapter like the ELM327 or Garmin EcoRoute, but it strikes me that there are enough security vectors in to the New Car that adding more is not a wise route. So, I'm thinking that the Raspberry Pi and an OBDII USB cable might be the better way to handle it, except I'm not sure how to export the data, and while it would be useful to keep track while driving, ultimately, off-the-road analysis is where the usefulness of the process comes in.

I'm thinking that a Raspberry Pi, a cable, a small monitor with composite video and maybe a few other things could be easily turned into a car-monitoring system, and I could pretty easily set something up to only sync with my home network when it's close. I'm not sure whether that's more cost-effective than just getting an ELM327 and an ELM327 app from the Play Store, but I think I'd end up learning more that way.

Anyway, I'm still undecided on the phone/Pi issue, but I think this is something I need to do.