NAME
canconfig —
configure CAN network
interface parameters
SYNOPSIS
canconfig |
can command
[args ...] |
DESCRIPTION
The
canconfig utility is used to configure CAN network
interface parameters and retrieve CAN network interface parameters and status
from the kernel.
Timing
The base time unit used to define the network bit rate is the time quanta (tq),
its value is defined by the input clock frequency and the prescaler value as
(1/ freq * prescaler).
The network bit time is split in 4 segments:
- sync_seg
- fixed to 1 tq
- prop_seg
-
- phase_seg1
-
- phase_seg2
-
The network bit time is (1 + prop_seg + phase_seg1 + phase_seg2), in tq. The
sample point is between phase_seg1 and phase_seg2.
The receiver hardware is allowed to shorten prop_seg or phase_seg2 to
resynchronize with the sender. The swj (Synchronisation Jump Width) parameter
defines by how much the hardware can shorten these segments.
Some hardware can use 3 sample points instead of one, and keep the majority as
the final value.
Options
The options are as follows:
-
-
- -a
- Display the status of all CAN devices present on the
system. This flag is mutually exclusive with all other sub-commands.
All other operations require that a CAN interface be specified. If a CAN
interface is specified with no sub-commands, the status of that interface is
displayed.
The following sub-commands are available:
-
-
- up
- Start network operations on the interface. Requires that
all timing parameters have been set.
-
-
- down
- Stop network operations on the interface.
-
-
- brp
value
- Set the value of the baud rate prescaler.
-
-
- prop_seg
value
- Set the number of tq for the propagation segment.
-
-
- phase_seg1
value
- Set the number of tq for the phase segment 1.
-
-
- phase_seg2
value
- Set the number of tq for the phase segment 2.
-
-
- sjw
value
- Set the number of tq for the Synchronisation Jump
Width.
-
-
- 3samples
- Enable triple-sampling.
-
-
- -3samples
- Disable triple-sampling.
-
-
- listenonly
- Enable listen-only mode. In this mode the controller is
passive, and doesn't send ACKs on the bus.
-
-
- -listenonly
- Disable listen-only mode.
-
-
- loopback
- Enable loopback mode. In this mode, the controller doesn't
expect ACK from the bus.
-
-
- -loopback
- Disable loopback mode.
SEE ALSO
ifconfig.if(5),
ifconfig(8)
HISTORY
The
canconfig utility first appeared in
NetBSD 8.0.
AUTHORS
This version of the
canconfig utility was written by
Manuel Bouyer.