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 -hUsage: cansend <device> <can_frame>

如果出现帧错误，请尝试下面的操作：

<can_id>#{R|data}          for CAN 2.0 frames<can_id>##<flags>{data}    for CAN FD frames<can_id> can have 3 (SFF) or 8 (EFF) hex chars
{data} has 0..8 (0..64 CAN FD) ASCII hex-values (optionally separated by '.')
<flags> a single ASCII Hex value (0 .. F) which defines canfd_frame.flagse.g. 5A1#11.2233.44556677.88/123#DEADBEEF/5AA#/123##1/213##3111F334455#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 can0can0  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] <CAN interface>+(use CTRL-C to terminate candump)Options: -t <type>   (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 <level>  (silent mode - 0: off (default) 1: animation 2: silent)-b <can>    (bridge mode - send received frames to <can>)-B <can>    (bridge mode - like '-b' with disabled loopback)-u <usecs>  (delay bridge forwarding by <usecs> microseconds)-l          (log CAN-frames into file. Sets '-s 2' by default)-L          (use log file format on stdout)-n <count>  (terminate after receiption of <count> CAN frames)-r <size>   (set socket receive buffer to <size>)-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 <msecs>  (terminate after <msecs> without any reception)Up to 16 CAN interfaces with optional filter sets can be specified on the commandline in the form: <ifname>[,filter]*Comma separated filters can be specified for each given CAN interface:<can_id>:<can_mask> (matches when <received_can_id> & mask == can_id & mask)<can_id>~<can_mask> (matches when <received_can_id> & mask != can_id & mask)#<error_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] 475Board $> 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