I have a car headunit which is touch screen and it has RCA AV input option. I've connected a raspberry pi using a HDMI to RCA convertor. The raspberry pi shows up on the screen. I want to run OpenAuto on the Pi but ideally want to be able to control it from the touch screen of the headunit. I know the touch screen is basically a digitizer that has a ribbon cable. So wondering if there is a way to get signal from the touch screen to the Pi to act as a input device?