Xenomai RTCAN
Contents
General Information
Xenomai provides a RTDM profile for CAN device drivers enabling real-time CAN communication. The driver exposes a real-time interface similar to the standard SocketCAN interface. Xenomai provides several user-space tools to enable simple interface testing. The following sections will provide the information needed to load the CAN driver, configure the interface, and communicate using the command line utilities provided with Xenomai.
Xenomai RTCAN
Loading the driver
If a Linux driver has already been associated with the CAN interfaces, it is required to unload the standard Linux driver or unbind that device for the driver. All of the examples below are using SoM-iMX6 for reference.
If the standard Linux CAN driver is built as a module, the module can just be unloaded using rmmod.
root@somimx6-xenomai:~# lsmod
Module Size Used by
can_raw 6668 0
can 28850 1 can_raw
rt_fec 14450 0
rtnet 51349 1 rt_fec
fec 37316 0
flexcan 9971 0
can_dev 11309 1 flexcan
root@somimx6-xenomai:~# rmmod flexcan
Once the standard Linux CAN driver is unloaded, the Xenomai real-time CAN driver can be loaded.
root@somimx6-xenomai:~# modprobe xeno_can_flexcan
[ 662.498586] RT-Socket-CAN 0.90.2 - (C) 2006 RT-Socket-CAN Development Team
[ 662.509318] 2090000.flexcan supply xceiver not found, using dummy regulator
[ 662.516398] rtcan: registered rtcan0
[ 662.520047] flexcan 2090000.flexcan: RTCAN device registered (reg_base=c0c70000, irq=142, clock=30000000)
[ 662.529809] 2094000.flexcan supply xceiver not found, using dummy regulator
[ 662.536881] rtcan: registered rtcan1
[ 662.540504] flexcan 2094000.flexcan: RTCAN device registered (reg_base=c0c78000, irq=143, clock=30000000)
Configuring CAN interface
With the real-time CAN driver loaded the rtcanconfig utility can be used to configure the bitrate and modes.
root@somimx6-xenomai:~# rtcanconfig rtcan0 --baudrate=125000 start
[ 706.101002] rtcan0: real bitrate 125000, sampling point 87.5%
[ 706.106857] rtcan0: writing ctrl=0x0e312005
[ 706.111091] rtcan0: flexcan_set_bit_time: mcr=0x5980000f ctrl=0x0e312005
[ 706.117801] rtcan0: flexcan_chip_start: writing mcr=0x79a2020f
[ 706.123511] rtcan0: flexcan_chip_start: writing ctrl=0x0e31ac55
[ 706.129581] rtcan0: flexcan_chip_start: reading mcr=0x69a2020f ctrl=0x0e31ac55
Communicating with CAN
Xenomai provides two command line utilities to communicate with the CAN interface: rtcansend and rtcanrecv.
Sending a CAN transaction using rtcansend.
root@somimx6-xenomai:~# rtcansend rtcan0 -v -i 0x0 0x82 0x1
interface rtcan0
s=3, ifr_name=rtcan0
<0x000> [2] 82 01
Cleaning up...
Receiving a CAN transaction using rtcanrecv.
root@somimx6-xenomai:~# rtcanrecv rtcan0 -v
interface rtcan0
s=3, ifr_name=rtcan0
External Links
- https://xenomai.org/documentation/xenomai-3/html/man1/rtcanconfig/index.html
- https://xenomai.org/documentation/xenomai-3/html/man1/rtcanrecv/index.html
- https://xenomai.org/documentation/xenomai-3/html/man1/rtcansend/index.html
- https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__rtdm__can.html
