CAN bus Linux driver

WORK IN PROGRESS

The current CAN bus driver uses SocketCAN API which is now the official CAN API for Linux.

SocketCAN is based on the Linux socket. Further details can be found on the links at the bottom of this page.

Driver installation

$ make linux26-menuconfig

in Device Drivers  ---> SPI support  --->  select <M> Freescale iMX SPI controller as module

in Networking  --->  select <M>   CAN bus subsystem support  as module
in Networking  ---> CAN bus subsystem support -->  select <M> Raw CAN Protocol  as module
in Networking  ---> CAN bus subsystem support -->  select <M> Broadcast Manager CAN Protocol  as module
in Networking  ---> CAN bus subsystem support --> CAN Device Drivers -->  select <M> Virtual Local CAN Interface  as module
in Networking  ---> CAN bus subsystem support --> CAN Device Drivers -->  select <M> Microchip 251x series SPI CAN Controller  as module

Usage

• load all the needed drivers:

insmod /lib/modules/drivers/spi/spi_imx.ko
insmod /lib/modules/2.6.23.1/kernel/net/can/can.ko
insmod /lib/modules/2.6.23.1/kernel/net/can/candev.ko
insmod /lib/modules/2.6.23.1/kernel/net/can/can-raw.ko
insmod /lib/modules/2.6.23.1/kernel/drivers/net/can/mcp251x.ko

Quick test

Once the driver installed, the CAN interface has to be started like a standard net interface

ifconfig can0 up

and can be stopped like that:

ifconfig can0 down

The socketCAN version can be retrieved like that:

cat /proc/net/can/version

The socketCAN statistics can be retrieved like that:

cat /proc/net/can/stats

Userspace tools

• Several tools are provided by socketCAN:
  • candump: dump traffic on a CAN network
  • cansend: simple command line tool to send CAN-frames via CAN_RAW sockets
  • cangen: CAN frames generator for testing purpose
  • canplayer: send CAN frames from a file to a CAN interface

• These tools can be compiled and installed on the target by means of the buildroot menuconfig:

[armadeus]$ make menuconfig

DevFull Can Bus

• The default baud rate is 250 kbaud.
• The CAN Connector (X2) is wired this way :
  • X2.1 = +5Vdc
  • X2.2 = CANH
  • X2.3 = CANL
  • X2.2 = GND

Links

• http://developer.berlios.de/projects/socketcan/ (CAN Linux Driver)
• http://ww1.microchip.com/downloads/en/DeviceDoc/21801e.pdf (MCP2515 datasheet)
• http://www.kvaser.com/can/protocol/index.htm (CAN introduction)