Configuration

The CAN-BUS FD controller card is configured by adding a few overlay lines to /boot/config.txt and then configuring the network interfaces file

Here are the two sections that need adding, note that the CM4 Based XT Integrator board uses different hardware chip-select pins to the other versions so use the applicable line when adding to config.txt

/boot/config.txt

dtoverlay=spi0-on
# Integrator Board OG/NT
dtoverlay=spi0-2cs,cs0_pin=8,cs1_pin=7
# Integrator Board XT
#dtoverlay=spi0-2cs,cs0_pin=8,cs1_pin=23
# CAN-FD Overlays
dtoverlay=mcp251xfd,spi0-0,interrupt=25
dtoverlay=mcp251xfd,spi0-1,interrupt=26

To configure the card in standard CAN 2.0 Mode (500kbps) use the below setup

 /etc/network/interfaces.d/can

############### CAN BUS CONFIG ###########################
auto can0
iface can0 inet manual
    pre-up ip link set $IFACE type can bitrate 500000 listen-only off
    up /sbin/ifconfig $IFACE up
    down /sbin/ifconfig $IFACE down

auto can1
iface can1 inet manual
    pre-up ip link set $IFACE type can bitrate 500000 listen-only off
    up /sbin/ifconfig $IFACE up
    down /sbin/ifconfig $IFACE down
############### CAN BUS CONFIG ###########################

To configure the card in CAN FD Mode (500kpbs / 2Mbps). use the below setup

 /etc/network/interfaces.d/can

	
############### CAN BUS CONFIG ###########################
auto can0
iface can0 inet manual
    pre-up ip link set $IFACE type can bitrate 500000 listen-only off dbitrate 2000000 fd on sample-point .7 dsample-point .7
    up /sbin/ifconfig $IFACE up
    down /sbin/ifconfig $IFACE down

auto can1
iface can1 inet manual
    pre-up ip link set $IFACE type can bitrate 500000 listen-only off dbitrate 2000000 fd on sample-point .7 dsample-point .7
    up /sbin/ifconfig $IFACE up
    down /sbin/ifconfig $IFACE down
############### CAN BUS CONFIG ###########################

With these changes in place reboot the unit and check the config as below

root@raspberrypi:~# ifconfig can0
can0: flags=193<UP,RUNNING,NOARP>  mtu 72
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 63

root@raspberrypi:~# ifconfig can1
can1: flags=193<UP,RUNNING,NOARP>  mtu 72
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 64

root@raspberrypi:~# 

IO Card Connector Pinout

This card has the following pin out on the front Green Industrial 8pin Connector Connector pin numbered left to right from front of card

Testing

To test the setup in a loopback mode use a short 2 wire cable to join together the CAN0-L + CAN1-L and CAN0-H + CAN1-H and fit 120R termination resistors at either ends so the bus resistance measures 60R when powered off.

Install the can-utils package

root@raspberrypi:~# apt-get install can-utils

Next setup two terminal windows and run cangen & candump as shown below

Basic CAN FD messages can be sent using the cansend commands

To send a CAN FD message with BRS use :

cansend can0 7df##15555555555555555

To send a CAN FD message with no BRS use :

cansend can0 7df##05555555555555555