CAN
Overview⚓︎
CAN (Controller Area Network) is a bus type network where all nodes on a single bus communicates directly with each other.
Host Mobility Hardware all have a number of CAN channels.
In Linux, CAN channels are implemented as network interfaces. They can utilize the Linux network stack and present a programming model similar to TCP/IP. Applications use the SocketCAN API, either directly or though a higher level library.
Platform specific⚓︎
Configuration though Systemd-Networkd⚓︎
Note: Not for BSP release 1.6/1.5 and older
Bus parameters can be set in systemd-networkd configuration files.
Example:
Edit or create /lib/systemd/network/80-can.network
Manual configuration⚓︎
Use ip link to configure the bus parameters manually. This is a standard utility(iproute2)
Supported options are shown by the ip help subcommand
$ ip link set can0 type can help
Usage: ip link set DEVICE type can
[ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
[ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]
[ loopback { on | off } ]
[ listen-only { on | off } ]
[ triple-sampling { on | off } ]
[ one-shot { on | off } ]
[ berr-reporting { on | off } ]
[ fd { on | off } ]
[ fd-non-iso { on | off } ]
[ presume-ack { on | off } ]
[ restart-ms TIME-MS ]
[ restart ]
Where: BITRATE := { 1..1000000 }
SAMPLE-POINT := { 0.000..0.999 }
TQ := { NUMBER }
PROP-SEG := { 1..8 }
PHASE-SEG1 := { 1..8 }
PHASE-SEG2 := { 1..8 }
SJW := { 1..4 }
RESTART-MS := { 0 | NUMBER }
Example : Set Standard (2.0) CAN with a bitrate of 500 kbit/s and listen-only mode.
Example : Set up CAN-FD with a bitrate of 500/4000 kbit/s in normal mode.
Query a device for its current configuration⚓︎
8: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
link/can promiscuity 0 minmtu 0 maxmtu 0
can <FD> state ERROR-PASSIVE (berr-counter tx 0 rx 127) restart-ms 0
bitrate 500000 sample-point 0.875
tq 25 prop-seg 34 phase-seg1 35 phase-seg2 10 sjw 1 brp 1
m_can: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
dbitrate 4000000 dsample-point 0.700
dtq 25 dprop-seg 3 dphase-seg1 3 dphase-seg2 3 dsjw 1 dbrp 1
m_can: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..32 dbrp_inc 1
clock 40000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 parentbus spi parentdev spi3.0
Query a device for statistics⚓︎
8: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
link/can
RX: bytes packets errors dropped missed mcast
0 0 0 0 0 0
TX: bytes packets errors dropped carrier collsns
0 0 0 0 0 0
CAN-utils⚓︎
can-utils is a collection of CAN-tools that can be used to debug CAN networks and applications. They can be very useful as a source of inspiration if you are to write your own application that interacts with a CAN network.