[Ivan] had a simple idea: being able to control his Android device from the small keypad on his car’s steering column. This would allow him to cycle through apps, navigation, and audio tracks while never taking his hands off the wheel. Feature creep then set in and [Ivan] asked himself how he could charge his phone through the same interface. What he ended up with is a head unit that’s also a dock.
While [Ivan]’s steering wheel doesn’t have the nice integrated remote control buttons found in newer cars, he does have a Blaupunkt remote, a small, clip-on controller that has a an IR transmitter on it. The IR receiver was connected to a PIC microcontroller, sending commands to the phone for up, down, left, right, menu, and home. Audio output from the phone is handled by a small USB sound card connected to a USB hub, sending the audio signals directly into the head unit’s amplifier.
Having the phone charge while it’s still in USB host mode is the crucial part of this build; not being able to charge on a long car ride would quickly drain the battery and make a car dock kind of pointless. To accomplish this, [Ivan] simulated a Galaxy S4 dock with a few resistors in the USB port, allowing the phone to control the USB sound card, listen to the emulated keyboard and mouse, and charge at the same time.
It’s not a pretty build, but it is extraordinarily useful. In the videos you can see that [Ivan] pretty much pulled this build together from stuff he had sitting around – a great reuse of junk, and a great addition to his car at the same time.