Prius carputer

If you want to use the steering wheel controls, you might as well stock with the factory head unit. You more than likely have an Aux input anyway. What the seller has said about the cigarette power is true. If you try to power the PC from it, you're asking for melted wiring, but it will work fine for your ignition/remote wire. The PC itself you should run directly from the battery terminal, and can be grounded anywhere to the body of the car close to the actual PC. I don't see why you need a yellowtop battery though. Any good power supply is going to have a startup/shutdown controller with a power cut feature to save your battery anyway. As for your touchscreen, yes it's expensive but you get what you pay for. Xenarc and Lilliput are the two most used and documented brands in the CarPC world and I recommend you stick with them to avoid headaches later. I can't really help you further with anything Prius specific because I haven't started my own build yet, but if you have other questions, hit me up. Also, check out mp3car.com forums for tons of CarPC info.

 

Also, a slimline USB DVD player in the glove compartment would give you easy access to DVD playing for the kids. Just remember video within view of the driver is illegal, so be prepared to switch to something else at short notice.

 

If you want to use the steering wheel controls then you need to make an interface. This isn't hard, if you're reasonably handy with electronics, as the buttons just switch a resistor each, so all that's needed is a means of measuring the resistance and converting this to a signal the carputer can understand. If it were me, then I'd use a simple microcontroller with an analogue input to measure the steering wheel control signal and output a serial data stream to the carputer. I wouldn't be surprised if someone already makes such a thing, as the majority of cars use resistive switching for steering wheel control signalling.

As for power, the easy way is to just tap into the existing head unit power feed. The simple way to do this would be to buy a Toyota harness adapter (the Prius uses the same head unit connectors as the Camry and Rav 4, plus a few other recent models). You could pretty much get every connection you needed by getting one of these and butchering it for the connectors.

 

Something like this should give you control from the steering wheel.

RcJoyCon - Play Racing Games with your RC Controller

 

Not advisable for a CarPC power supply. The wire gauge to a factory head unit or even nav head unit is almost never sufficient to safely power a PC, especially if the LCD is going to be wired to the PC's secondary power headers.

 

Heck, how much power do you need for chrisakes? There is around 240W available via the standard loom at that point, which is plenty for any reasonably modern carputer, or even an old one using pretty power hungry technology. If it isn't, then getting all that heat out of such a small box tucked in the dash is going to be a real challenge!

The LCD only needs around 5W, BTW, so is negligible in terms of overall power consumption. A decent carputer based around the dual core Atom might use around 4 or 5W, leaving masses of spare power capability for decent amps and peripherals.

In essence all these Chinese DVD/Nav units are just carputers anyway, albeit using pocket PC technology rather than PC technology. There's little to choose between the two in terms of power consumption now, with some of the newer small form factor PC boards being so frugal in terms of power demand.