Putting this Arduino module between your aftermarket Android head unit with a rotary encoder allows volume control via the knob. Requires 2 n-channel MOSFETs to be driven from the Arduino Pro Micro
This code has been written to run on an Arduino Pro Micro. It should be easy to port it to other Arduino boards.
This code depends on the CruisingGeekCommon library. You can find that library here: https://github.com/CruisingGeek/CruisingGeekCommon Unpack that library into your Arduino libraries folder.
This code also depends on a 3rd party RotoryEncoder library you can find here: https://github.com/mathertel/RotaryEncoder Unpack this into your libraries folder as well.
If you are building this project and would like the mosfet board to switch the two external resistors, please contact me @ CruisingGeek@gmail.com
The following are wiring diagrams using both the MOSFET board and for generic MOSFETs
