CANFDZeroHAT

Raspberry Pi HAT with Microchip MCP2517FD or MCP2518FD CAN FD controller

The board uses a 40 MHz crystal. This is the default crystal for the linux module. The first prototypes used a 20 MHz crystal.

The controller can be connected to SPI0 CE0 or CE1 by populating different resistor jumpers. Also different GPIOs can be used as interrupt.

setup

edit /boot/config.txt and add line:

dtoverlay=mcp251xfd,spi0-0,interrupt=25

If you use a crystal different to 40 MHz you have to specify the frequency:

dtoverlay=mcp251xfd,spi0-0,oscillator=20000000,interrupt=25

keep care that you choose the right interrupt and SPI CE line and populate the corresponding resistor.

enable CAN after boot up with

sudo ip link set can0 up type can bitrate 250000

connectors

CAN connector CN2

Terminal block with 3.81 mm grid.

| Pin | Signal | Description | |:-------:|:-------------:|:--------------------------------:| | 1 | GND | | | 2 | CAN_L | | | 3 | CAN_H | | | 4 | VCC | up to 5.5 V |

UAVCAN dronecode connector CN3 and CN4

compatible to UAVCAN dronecode. JST GH 1.25mm 4-pin.

| Pin | Signal | Description | |:-------:|:-------------:|:--------------------------------:| | 1 | CANVCC | up to 5.5 V | | 2 | CAN_H | | | 3 | CAN_L | | | 4 | GND | |

CANVCC can be connected to the Raspberry Pi via diode D1 as desribed in the dronecode spec. The direction of the diode defines wether current is sourced from the connector or supplied into the UAVCAN system. If no connection is desired just leave D1 unpopulated.

PCB

Top

Bottom

Resources

Datasheets

• http://ww1.microchip.com/downloads/en/DeviceDoc/MCP2517FD-External-CAN-FD-Controller-with-SPI-Interface-20005688B.pdf
• https://ww1.microchip.com/downloads/en/DeviceDoc/External-CAN-FD-Controller-with-SPI-Interface-DS20006027B.pdf

License

This hardware is licensed under the CERN OHL v. 1.2