Here a Carberry board layout, with connectors highlighted.
Microfit 22 pin main connector, provides power supply and connections to vehicle.
Raspberry Pi Interface, joins toghether Carberry board and Raspberry Pi microcomputer.
Infrared Interface, provides connections to infrared extension (sensor and emitter).
For factory programming of microcontroller.
Debug Interface, provides connections to a debug interface (simple serial device).
Micro USB Interface, exposes USB device connection to external USB host.