CAN in linux
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This document discusses how to set up and use CAN utilities on Linux. It describes installing CAN-utils, loading CAN drivers, creating virtual CAN interfaces like vcan0, and using tools like cansend, candump, and cangw. CAN-utils contains tools for sending, receiving, and filtering CAN messages. The document also provides references for more information on Linux CAN and setting up real CAN hardware.
![Frequently used tools are highlighted
a.cansend and candump
To send a CAN message, using cansend there are two requirements 11 bit(0x000 to0x7FF)
/29 bit(0x00000000 to0x1FFFFFFF) identifier and message of length ranging from 0 to 8 bytes
To send a message(0x6789) of 2 bytes with 11bitidentifier (0x000) to interface vcan0,use
cansend vcan0 000#6789
To send a message(0x8679) of 8 bytes with 29 bit identifier (0x0123456789ABCDEF) to
interface vcan0,usecansendvcan0 0x0123456789ABCDEF#8679
Using Acceptance filtering (Refer https://discuss.cantact.io/t/using-can-utils/24 )
To filter messages whoseID is in the range 0x120 to 0x12F
Use candump vcan0,120:0x7F0
Messages arefiltered based on this condition
[received_can_id]&[can_mask] == [can_id] & [can_mask]
Here can_id = 0x120 and can_mask =0x7F0
& is a bitwise operator](https://image.slidesharecdn.com/caninlinux-170401062821/85/CAN-in-linux-4-320.jpg)
CAN in linux
- 1. 1. Install CAN-Utils Method 1: Using the command sudo apt-get install can-utils (OR) Method2: Download from https://github.com/linux-can/can-utils
- 2. Afterdownloadinguse the followingcommands unzipcan-utils-master.zip cd can-utils-master make sudo make install 2.Load CAN drivers (Reference: https://en.wikipedia.org/wiki/SocketCAN ) Use the following commands sudo modprobe can sudo modprobe vcan sudo modprobe can_raw sudo modprobe can_gw To list the kernel modules lsmod
- 3. Kernel modules can be found in /lib/modules/<kernel_version>/net/can/ Sourcecode is available at https://github.com/torvalds/linux/tree/master/net/can (or) <KERNEL_SRC>/net/can . Kernel sourcecan be downloaded from www.kernel.org 3.Creating virtual CAN node( Reference:https://en.wikipedia.org/wiki/SocketCAN ) Use the following commands to create a virtual CAN node vcan0 sudo ip link add dev vcan0 type vcan sudo ip link set up vcan0 Similarly repeat the abovecommands to a virtual CAN node vcan1 To list the details of network interfaces ,use ifconfig Use ifconfigvcan0 to know details of vcan0 4.UsingCAN-Utils CAN Utils contains the following tools asc2log, bcmserver, canbusload, can-calc-bit-timing, candump, canfdtest, cangen, cangw, canlogserver, canplayer, cansend, cansniffer, isotpdump, isotprecv, isotpperf, isotpsend, isotpserver, isotpsniffer, isotptun, log2asc,log2long, slcan_attach, slcand and slcanpty
- 4. Frequently used tools are highlighted a.cansend and candump To send a CAN message, using cansend there are two requirements 11 bit(0x000 to0x7FF) /29 bit(0x00000000 to0x1FFFFFFF) identifier and message of length ranging from 0 to 8 bytes To send a message(0x6789) of 2 bytes with 11bitidentifier (0x000) to interface vcan0,use cansend vcan0 000#6789 To send a message(0x8679) of 8 bytes with 29 bit identifier (0x0123456789ABCDEF) to interface vcan0,usecansendvcan0 0x0123456789ABCDEF#8679 Using Acceptance filtering (Refer https://discuss.cantact.io/t/using-can-utils/24 ) To filter messages whoseID is in the range 0x120 to 0x12F Use candump vcan0,120:0x7F0 Messages arefiltered based on this condition [received_can_id]&[can_mask] == [can_id] & [can_mask] Here can_id = 0x120 and can_mask =0x7F0 & is a bitwise operator
- 5. b.Using the CAN gateway utility (cangw): Ensurethat kernelmodule can_gw is loaded.You can check it using the command lsmod sudo cangw -F deletes all gateway rules sudo cangw -A -s vcan0 -d vcan1 -e -f 120:7F0 Adds a new rule with sourceas vcan0 , destination as vcan1 with echo enabled and which accepts messages of ID in the range 0x120 to 0x12F sudo cangw -A -s vcan0 -d vcan1 -e -f 200:7F0 Adds a new rule with sourceas vcan0 , destination as vcan1 with echo enabled and which accepts messages of ID in the range 0x200 to 0x20F cangw -L Lists all gateway rules
- 6. d. using cangen For more help and information, <utility_name> --help Eg: cangw --help cansend --help candump --help
- 7. Linux CAN Subsystem https://www.kernel.org/doc/Documentation/networking/can.txt For working on real CAN hardware https://harrisonsand.com/can-on-the-raspberry-pi/ ( http://www.ebay.in/itm/MCP2515-CAN-Bus-Module-TJA1050-receiver-SPI-For-51-MCU-ARM-controller-/131725452389 ) Author : Jabez Winston www.linkedin.com/in/jabezwinston