When starting with Openhab & Velserver on Raspberry PI I loved the flexibility of the software (including Openhab network bindings) but hated the cabling over USB and Velbus USB interface.
It seemed almost evident to use the PI for most interfacing but only the canBus interface was missing. For fun, I just created a small PI Hat providing the canBus interface and implementing the Velbus interface. This small hat uses the serial interface (/dev/serial0) and power supply available on the GPIO header of the PI.
Many thanks to Jeroen, Cedric and MDAR for sharing components and support!
The hat is based on a Microchip PIC24HJ chip.
Board development Eagle
Software: MPLAB C code