Jetson/AGX Xavier CAN

This page describes how to enable and verify CAN in Linux on Jetson AGX Xavier. Jetson AGX Xavier exposes two CAN instances: CAN0, CAN1.

=Hardware= Jetson Xavier Pin, Tegra Signal, Pin Type: https://developer.nvidia.com/embedded/dlc/jetson-xavier-oem-product-designguide, section 12.4 Pin exposed on Carrier board: http://developer.nvidia.com/embedded/dlc/jetson-xavier-developer-kit-carrier-board-spec, section 3.3 Note, there is not CAN transceiver on Jetson AGX Xavier module and Carrier board

=Software= This section includes CAN Driver Enable, CAN Verification and Socket CAN Program. To enable CAN driver, two steps below are needed:
 * 1) Update Pinmux
 * 2) Enable CAN by installing kernel modules and configuring the interface

Update Pinmux
To comply with Raspi 40-pin standard, the CAN I/O pins on Jetson AGX Xavier are configured to have GPIO functionality. To configure pins to CAN functionality, pinmux configure file needs to be changed.

Locate Pinmux configure file
PINMUX_CONFIG variable in $JETPACK_ROOT/Xavier/Linux_for_Tegra/jetson-xavier.conf defines pinmux configure file name like below. The pinmux configure file locates at $JETPACK_ROOT/Xavier/Linux_for_Tegra/bootloader/t186ref/BCT/. 
 * 1) !/bin/bash


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 * 1) p2972-0000-devkit.conf: configuration for T194 Silicon

source "${LDK_DIR}/p2972-0000.conf.common"; PINMUX_CONFIG="tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg";

Modify Pinmux
Set pinmux in configure file, in this case, it is $JETPACK_ROOT/Xavier/Linux_for_Tegra/bootloader/t186ref/BCT/tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg. Below is the change. pinmux.0x0c303000 and pinmux.0x0c303008 are for CAN1 while pinmux.0x0c303010 and pinmux.0x0c303018 are for CAN0. Or follow How to Update Pinmux to use tools to generate new configure file, the latter way is recommended.  diff --git a/tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg b/tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg index df43561..c61e80d 100644 --- a/tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg +++ b/tegra19x-mb1-pinmux-p2888-0000-a04-p2822-0000-b01.cfg @@ -322,10 +322,10 @@ pinmux.0x0243d010 = 0x00000059; # spi1_cs0_pz6: rsvd1, pull-up, tristate-enable, pinmux.0x0243d050 = 0x00000059; # spi1_cs1_pz7: rsvd1, pull-up, tristate-enable, input-enable, lpdr-disable pinmux.0x0c301010 = 0x00000059; # safe_state_pee0: rsvd1, pull-up, tristate-enable, input-enable, io_high_voltage-disable, lpdr-disable pinmux.0x0c301038 = 0x00000058; # power_on_pee4: rsvd0, pull-up, tristate-enable, input-enable, lpdr-disable -pinmux.0x0c303000 = 0x0000c055; # can1_dout_paa0: rsvd1, pull-down, tristate-enable, input-enable -pinmux.0x0c303008 = 0x0000c055; # can1_din_paa1: rsvd1, pull-down, tristate-enable, input-enable -pinmux.0x0c303010 = 0x0000c059; # can0_dout_paa2: rsvd1, pull-up, tristate-enable, input-enable -pinmux.0x0c303018 = 0x0000c059; # can0_din_paa3: rsvd1, pull-up, tristate-enable, input-enable +pinmux.0x0c303000 = 0x0000c400; # can1_dout_paa0: rsvd1, pull-down, tristate-enable, input-enable +pinmux.0x0c303008 = 0x0000c458; # can1_din_paa1: rsvd1, pull-down, tristate-enable, input-enable +pinmux.0x0c303010 = 0x0000c400; # can0_dout_paa2: rsvd1, pull-up, tristate-enable, input-enable +pinmux.0x0c303018 = 0x0000c458; # can0_din_paa3: rsvd1, pull-up, tristate-enable, input-enable pinmux.0x0c303020 = 0x0000c000; # can0_stb_paa4: rsvd0, tristate-disable, input-disable pinmux.0x0c303028 = 0x0000c000; # can0_en_paa5: rsvd0, tristate-disable, input-disable pinmux.0x0c303030 = 0x0000c058; # can0_wake_paa6: rsvd0, pull-up, tristate-enable, input-enable

Flash device
$ cd $JETPACK_ROOT/Xavier/Linux_for_Tegra/ $ sudo ./flash.sh jetson-xavier mmcblk0p1

Install CAN modules
By default, CAN is compiled as module. In this case, run below command on board to install modules. $ sudo modprobe can $ sudo modprobe can-raw $ sudo modprobe can-dev $ sudo modprobe mttcan

Set CAN
Now, two CAN instances are initialized: can0, can1. Choose can0 as an example.

Before setting CAN, run below command to make sure CAN is down. $ sudo ifconfig can0 down Set CAN bit rate (in this case 1000000) and bring CAN up. $ sudo ip link set can0 up type can bitrate 1000000 Now, can0 is ready to use.

Install can-utils
Follow https://elinux.org/Can-utils to install can-utils on Jetson AGX Xavier.

Send CAN Message
Below command can send CAN message: $ cansend can0 123#abcdabcd Below command can generate random CAN messages: $ cangen -v can0

Receive CAN Message
Below command can dump messages received by can0: $ candump can0

Socket CAN Program
https://en.wikipedia.org/wiki/SocketCAN has a working example of the SocketCAN API.