“This projects is a addon for my CAN bus extension project in order to add Android Auto functionality. The screen is displaying openauto on the stock Volvo RTI display using a Raspberry Pi and can be controlled using the stock steeringwheel buttons. When plugging in a phone using USB the display will automatically raise and start Android Auto. When the cable is removed or the ignition is switched off, the display will automatically turn off and lower.
CAN bus transceiver
Raspberry Pi 3
Volvo RTI (Road Traffic Information) display
12v to 5v converter
Apple USB C to 3.5 mm Audio
3.3 to 5V logic converter (Can be made using transistor and a few resistors)
Power control and safe shutdown
In a shutdown state my Raspberry Pi 3 still drew around ~250mA. The ESP32 therefore manages the power of the Pi. If there is no activity on the CAN bus for 1 minute (happens after locking car or waiting ~10 minutes without opening any doors) the ESP32 sends an shutdown command over serial to the Pi. A Python script will then safely shutdown the Pi. After 30 seconds the ESP32 will turn off the relay powering the Pi and enter deep sleep. Making the total power consumption around ~10mA. The CAN RX pin on the ESP32 triggers deepsleep wakeup and enables the Pi’s relay, restarting the process.
Driving the stock RTI
As an option on these P2 cars (S60, S80, V70 etc) one could get GPS navigation using a center screen and CD changer in the trunk. My car did not come with this option installed from the factory. It is however possible to add and drive the RTI display as a standalone unit.
The RTI uses two plugs; one for power and one for composite video and serial data. The serial bus operates at 1200 baud and can be controlled using your standard (5v) serial. The bus is used for switching display modes, moving the display up or down and changing brightness. All this information was obtained from various Volvo forums. Most information was found on the Swedish Volvo forum here
Because my car did not come with the stock RTI wiring harnass, I solderd wires for the constant 12v, switched 12v, ground, serial, video and video ground (Fig 1 & 2) directly to the RTI’s PCB.”