Using CAN in Linux

1 Detect & Init
2 Testing CAN
- 2.1 cangen
- 2.2 candump

Many of our Trizeps modules got an integrated CAN controller.
On others, this function may be added through additional chips like the Microchip MCP2518FD.

Detect & Init

See if CAN-adapter got registered:

root@imx8mmevk:~# ifconfig -a
can0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          NOARP  MTU:16  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth0      Link encap:Ethernet  HWaddr 8a:7b:51:54:3a:65
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth1      Link encap:Ethernet  HWaddr 0a:ea:42:e6:ee:90
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:90 errors:0 dropped:0 overruns:0 frame:0
          TX packets:90 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6708 (6.5 KiB)  TX bytes:6708 (6.5 KiB)

Activate Interface:

root@imx8mmevk:~# sudo ip link set can0 up type can bitrate 1000000
[   68.603002] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready
root@imx8mmevk:~# sudo ifconfig can0 txqueuelen 65536

On Debian and similar systems you can run CAN at startup by adding the following lines to your /etc/network/interfaces:

auto can0
iface can0 can static
        bitrate 1000000
        txqueuelen 65536

Testing CAN

The following tools are contained in the package can-utils. On Debian and it's relatives you can install it with:

cangen

Use cangen to generate CAN-packets to send over the interface. See 'cangen –help' for more information.
Example:

candump

Use candump to show received CAN-packets.