A fully custom infotainment system for my W211 E55 AMG based on a PC with a custom daughter board!
PROCEED AT YOUR OWN RISK! This project is for advanced users only as a lot of the code (Specifically the MCU code) has to be designed from scratch due to licensing issues.
THIS WILL ONLY WORK IF YOU HAVE AGW. Cars that just have the Radio module, and no AudioGateway module in the trunk will not be compatible with this project!
Hookup guide and general block diagram:
The touch input controller is based on an Arduino Micro and GT911 driven touch display. You can find the code for it under the touch_sw folder.
Check the schematics directory of this project for the Gerber and schematics of the daughter PCB!
The daughter board is powered by the SAME51J20A MCU, on the Microchip Curiosity nano (EV76S68A). Due to licensing issues with the MPLABX SDK, I cannot publish some code for this project, so below there is a guide on how to adapt your own code base to talk to the PC.
Below is a hookup table showing the IO of the PCB
| CPU PIN | CPU PORT | Function | Description |
|---|---|---|---|
| 12 | PortB | CAN C Tx | |
| 13 | PortB | CAN C Rx | |
| 12 | PortA | CAN C shdn | When set to high, the CAN C transceiver will shut down to save some power when the MCU goes to sleep when the car is off |
| 22 | PortA | CAN B Tx | |
| 23 | PortB | CAN B Rx | |
| 27 | PortA | AMP Standby | When high, standby is disabled, when low, standby is enabled. Check the TDA IC datasheets for how standby works |
| 05 | PortA | AMP Mute | When high, the Amplifier can output sound. When low, the amplifier is muted. Check the TDA IC datasheets for how mute works |
| 01 | PortB | Front panel power btn | Trigger on voltage change |
| 00 | PortB | Front panel hazards btn | Trigger on voltage change |
| 07 | PortB | PC Power button | Allows the MCU to turn the PC on by emulating the power button press of the PC |
| 06 | PortB | PC Reset button | Allows the MCU to force reset the PC on by emulating the reset button press of the PC |
| 04 | PortB | Amplifier power MOSFET | Allows toggling power to the whole amplifier circuity on the PCB |
| 05 | PortB | PC power MOSFET | Allows toggling power to the PC and front display |
| 07 | PortA | ADC Voltage sense | Allows for monitoring the supply voltage to the board |
| 04 | PortA | ADC INA input PC | Current measuring of the PC circuitry |
| 09 | PortA | ADC INA input AMP | Current measuring of the amplifier circuitry |
NOTE. The PC should be designed to NEVER draw more than 250W!. Doing so could blow the AGW fuse and overload the stock wiring harness.
- Pico PSU that can handle 6-35V (Automotive safe).
The MCU and PC talk to one another over an emulated CAN network that runs over a USB cable.
The format of this protocol is very simple, and runs at a 115200 baud rate:
The MCU sends an ASCII encoded string to the PC for every CAN frame:
[BUS TAG][ID (Hex)] [DATA]\n
Example:
C000C 0011223344\n
This would indicate a frame on bus C that has an ID of 0x000C, and data of [0x00, 0x11, 0x22, 0x33, 0x44]
The PC sends byte packed structures to the MCU (This is faster for the MCU to decode rather than ASCII strings)
typedef struct {
// Bus tag character
char can_id;
// CAN ID
uint16_t id;
// CAN DLC
uint8_t dlc;
// Data array
uint8_t data[8];
} __attribute__ ((packed)) PcFrame;- C - Frame is to/from CAN C (powertrain CAN of W211)
- B - Frame is to/from CAN B (interior CAN of W211)
- E - Frame is a status frame that is transmitted to/from the PC and MCU for systems status. You can check the DBC for the formats of these frames.