[Benjamin] was working for a GPS business called Nemerix about two years back as well as chose to hack together this iPod accessory GPS unit. He is utilizing an Atmel ATmega324 as well as a Nemerix GPS unit, though he states the GPS system shouldn’t matter. He is taking advantage of the AiR mode on the iPod which enables a 4 color picture to be sent to the screen. There was bit info on exactly how to use this, however BMW as well as Alpine had made some vehicle audio that featured this. [Benjamin] chosen up an Alpine with this function as well as sniffed the data stream to get what he needed. He states there is great documentation available now though.
He states that the source code is offered if you ask.