CAN发送和接收数据

1.如何发送或接收 CAN 数据

目的 本文介绍如何使用 can-utils [1 ]包在 SocketCAN 接口上发送/接收数据。

can-utils 包含一些用于 Linux®SocketCAN 子系统的用户空间实用程序。它已集成在STM32微处理器系列的 SDK 中。在此示例中，仅使用到 cansend 和 candump，但软件包中还提供了许多其他的工具。
准备条件
至少需要两个设备才能在 CAN 网络上进行通信。要实现这种配置，请在同一 CAN 总线上连接两个设备。然后，从一个节点发送数据，并在另一节点上接收数据。
在开始通信之前，必须在每块板上配置并启用 SocketCAN 接口。请参阅如何设置 SocketCAN 接口。

在CAN总线上发送数据

要发送单个帧，请使用 cansend 实用程序：

Board $> cansend can0 123#1122334455667788

获取 cansend 实用程序中的使用帮助信息：

Board $> cansend -h
	Usage: cansend  

如果出现帧错误，请尝试下面的操作：

#{R|data}          for CAN 2.0 frames
  	##{data}    for CAN FD frames

 can have 3 (SFF) or 8 (EFF) hex chars
{data} has 0..8 (0..64 CAN FD) ASCII hex-values (optionally separated by '.')
 a single ASCII Hex value (0 .. F) which defines canfd_frame.flags

e.g. 5A1#11.2233.44556677.88/123#DEADBEEF/5AA#/123##1/213##311
   1F334455#1122334455667788/123#R for remote transmission request.

在CAN总线上接收数据

要实时显示总线上收到的消息列表，请使用 candump 实用程序：

Board $> candump can0
	can0  123   [8] 11 22 33 44 55 66 77 88

在 candump 实用程序上获取帮助信息：

Board $> candump -h

Usage: candump [options] +
   (use CTRL-C to terminate candump)

Options: -t    (timestamp: (a)bsolute/(d)elta/(z)ero/(A)bsolute w date)
         -c          (increment color mode level)
         -i          (binary output - may exceed 80 chars/line)
         -a          (enable additional ASCII output)
         -S          (swap byte order in printed CAN data[] - marked with '`' )
         -s   (silent mode - 0: off (default) 1: animation 2: silent)
         -b     (bridge mode - send received frames to )
         -B     (bridge mode - like '-b' with disabled loopback)
         -u   (delay bridge forwarding by  microseconds)
         -l          (log CAN-frames into file. Sets '-s 2' by default)
         -L          (use log file format on stdout)
         -n   (terminate after receiption of  CAN frames)
         -r    (set socket receive buffer to )
         -D          (Don't exit if a "detected" can device goes down.
         -d          (monitor dropped CAN frames)
         -e          (dump CAN error frames in human-readable format)
         -x          (print extra message infos, rx/tx brs esi)
         -T   (terminate after  without any reception)

Up to 16 CAN interfaces with optional filter sets can be specified on the commandline in the form: [,filter]*

Comma separated filters can be specified for each given CAN interface:
 : (matches when  & mask == can_id & mask)
 ~ (matches when  & mask != can_id & mask)
 #       (set error frame filter, see include/linux/can/error.h)
 [j|J]               (join the given CAN filters - logical AND semantic)

CAN IDs, masks and data content are given and expected in hexadecimal values.
When can_id and can_mask are both 8 digits, they are assumed to be 29 bit EFF.
Without any given filter all data frames are received ('0:0' default filter).

Use interface name 'any' to receive from all CAN interfaces.

Examples:
candump -c -c -ta can0,123:7FF,400:700,#000000FF can2,400~7F0 can3 can8
candump -l any,0~0,#FFFFFFFF    (log only error frames but no(!) data frames)
candump -l any,0:0,#FFFFFFFF    (log error frames and also all data frames)
candump vcan2,92345678:DFFFFFFF (match only for extended CAN ID 12345678)
candump vcan2,123:7FF (matches CAN ID 123 - including EFF and RTR frames)
candump vcan2,123:C00007FF (matches CAN ID 123 - only SFF and non-RTR frames)

硬件自检

在内部环回测试模式下，FDCAN将发送的消息作为接收消息进行处理。此选项用于硬件自检（无需在 CAN 总线上连接外部 CAN 节点）。
要在回环模式下配置和启用 SocketCAN，请执行以下操作：

Board $> ip link set can0 up type can bitrate 1000000 dbitrate 2000000 fd on loopback on
	[ 78.700698] m_can 4400e000.can can0: bitrate error 0.3%
	[ 78.704568] m_can 4400e000.can can0: bitrate error 1.6%
	[ 78.710140] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready

要在同一接口上发送和接收消息，请按照下列步骤操作：

Board $> candump can0 -L &
	[1] 475
	Board $> cansend can0 300#AC.AB.AD.AE.75.49.AD.D1
	(1539944874.949723) can0 300#ACABADAE7549ADD1
	(1539944874.949683) can0 300#ACABADAE7549ADD1

2.Socket CAN指令详解

1、#ip link set canX down //关闭can设备；
2、#ip link set canX up   //开启can设备；
3、#ip -details link show canX //显示can设备详细信息；
4、#candump canX  //接收can总线发来的数据；
5、#ifconfig canX down //关闭can设备，以便配置;
6、#ip link set canX up type can bitrate 250000 //设置can波特率
7、#conconfig canX bitrate + 波特率；
8、#canconfig canX start //启动can设备；
9、#canconfig canX ctrlmode loopback on //回环测试；
10、#canconfig canX restart // 重启can设备；
11、#canconfig canX stop //停止can设备；
12、#canecho canX //查看can设备总线状态；
13、#cansend canX --identifier=ID+数据 //发送数据；
14、#candump canX --filter=ID：mask//使用滤波器接收ID匹配的数据

参考http://wiki.100ask.org/index.php?title=How_to_send_or_receive_CAN_data&oldid=6022