An Arduino, AVR-based CD changer emulator for Volkswagen car audio head units, allowing bidirectional communication with the in-car stereo system over a serial connection from the board to another device.
VW head units speak an ill-documented protocol with CD changer devices located usually in the back of the car. My goal is to replace my PhatNoise Media System with an arbitrary computing platform.
My motivation in creating this VW CD Changer Emulator is to make a simple embedded board which will allow me to build my own PhatNoise-esque system with complete control over the head unit. The architecture I'm currently working with will consist of:
- Hopefully, a very minimal Arduino board, as the only physical requirements are four pins for SPI communication with the head unit, and UART or a Serial Port for external communication with an application driving the head unit and responding to key presses/events.
- A Raspberry Pi or other small, low-power computer which will bidirectionally communicate with the Arduino board over UART/Serial.
- A daemon written in Rust for streaming analog audio to the head unit and controlling media playback.
- A voltage regulator and battery, keying off of the 12V+ DC accessory power supply, which is only on when the key is turned to or past the accessory switch.
Once this very simple setup has been achieved, other experiments may follow:
- Put a Bluetooth receiver on the Raspberry Pi and write an Android application which will be able to communicate with the Raspberry Pi from my phone.
- Put an LTE antenna and SIM card for roaming internet access.
- Put one or two WiFi antennas, one as a client to be able to connect to my home WiFi and one as a server for in-car communication.
- Use Syncthing to keep my music library in sync on the Raspberry Pi and my other home devices.
Having a full computing platform in the back of the car will enable lots of other exciting experiments and projects.
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