Hi, This is example of Arduino promicro as signals translator. Navigation joystick from Renault cars 2005-2016. CAN signals are translated by MCP2515 + promicro + digi pot x9c103 ... then to radio via analog key1/key2 5v wires. Those radios are not pure Android devices so promicro USB keyboard will not work well... If you decide to go with USB keyboard only, you will have to install apps like "Key mapper" "on screen volume" some "media button volume only" also tool to limit volume... and worst is that this radio "accessibility" will start turn OFF your applications from time to time (without root you will not stand it). On the very end most useful seems to do it in old way via resistance buttons. Instead 10K ohm x9c103 pot use 104 (100 k ohm) (or some MCP41100 or 41050) series since 10k 103 will allow only for max 4-5 buttons in case of this radio. Personally I can not recommend 2/32G 4CPU head units, are very slow, radio (with external antenna amplifier) works terrible, loosing frequency and signal all the time, G map is slower then anything I've seen before.
