【全志T113-i】OK113i-S开发板CAN通信C代码测试

飞凌官方手册中关于CAN测试部分使用的是命令行进行的简单测试，实际开发过程中还是要使用C代码去操作CAN设备，本帖主要讲解怎么使用C代码对CAN设备进行读写的收发操作。

First of all ，先查看所有网卡信息，看看板上是否有CAN设备网络：

root@ok113i:/# ifconfig -a
can0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  NOARP  MTU:16  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:10 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)can1      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  NOARP  MTU:16  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:10 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)Interrupt:1 eth0      Link encap:Ethernet  HWaddr BA:E9:F2:1C:9D:87  inet addr:192.168.0.232  Bcast:0.0.0.0  Mask:255.255.255.0inet6 addr: fe80::b8e9:f2ff:fe1c:9d87/64 Scope:LinkUP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1RX packets:421 errors:0 dropped:14 overruns:0 frame:0TX packets:9 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000 RX bytes:27272 (26.6 KiB)  TX bytes:726 (726.0 B)Interrupt:39 ip6tnl0   Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  NOARP  MTU:1452  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)lo        Link encap:Local Loopback  inet addr:127.0.0.1  Mask:255.0.0.0inet6 addr: ::1/128 Scope:HostUP LOOPBACK RUNNING  MTU:65536  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)sit0      Link encap:IPv6-in-IPv4  NOARP  MTU:1480  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)wlan0     Link encap:Ethernet  HWaddr 2C:C3:E6:67:4D:3B  BROADCAST MULTICAST  MTU:1500  Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

1. CAN组网前的准备，设置CAN通信服务的通信速率。

使用如下命令分别设置CAN0和CAN1的通信速率：

root@ok113i:/home/forlinx# ip link set can0 up type can bitrate 500000
[ 4075.425084] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready
root@ok113i:/home/forlinx# ip link set can1 up type can bitrate 500000                                   
[ 4086.037967] IPv6: ADDRCONF(NETDEV_CHANGE): can1: link becomes ready

以上设置can0 和 can1 通信速率均为500kbps，这个速率值务必记住，所有接入组网的的can节点都是以这个速率通信。

2. 使用C语言写一个CAN通信的发送接收测试程序，主要验证CAN发送和接收数据是否正常。

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <signal.h>
#include <string.h>#include "can_apply.h"#define MASTR_CAN1_ID      0x100
#define MASTR_CAN2_ID      0x101#define RX_MSG_NUM           16
#define MAX_BUF_LEN          64typedef enum
{CAN_1,CAN_2,CAN_RES
}can_type;typedef struct{int can_id;unsigned char can_dlc;unsigned char data[MAX_BUF_LEN];
}can_msg_t;static int bexit = 0;
static int can0_sock,can1_sock;
can_msg_t can_rx_msg[RX_MSG_NUM];
unsigned int can1_id = 0;
unsigned int can2_id = 0;void signal_handler(int signo)
{printf("signal %d(%s) received\n", signo, strsignal(signo));bexit = 1;}int can_send_data(can_type type, unsigned char *buf, int len)
{int i, j;int cnt;int sock;int ret = 0;struct can_frame frame;if(type == CAN_1){sock = can0_sock;frame.can_id = can1_id;}else {sock = can1_sock;frame.can_id = can2_id;}for(i = 0; i < len; i += 8){cnt = len - i;if(cnt > 8)frame.can_dlc =  8;elseframe.can_dlc = cnt;for(j=0; j<frame.can_dlc; j++){frame.data[j] = buf[i+j];}if(can_send(sock, frame) < 0){ret = -1;break;}}return ret;
}void can_recv_data(int sock)
{static unsigned char tail = 0;int i;int can_id;unsigned char can_dlc;unsigned char *data;struct can_frame frame;int index = can0_sock == sock ? 0 : 1;if(can_recv(sock, &frame) < 0)return ;can_id = frame.can_id;can_dlc = frame.can_dlc;data = frame.data;printf("CAN%d dlc = %d, can_id = %x\ndata:", index,frame.can_dlc, frame.can_id);for(i=0; i<frame.can_dlc; i++)printf("0x%02x ", frame.data[i]);printf("\n");}void *can_proc_start(void *arg)
{int nready;int maxfd;fd_set readfds;int sock = *(int *)arg;FD_ZERO(&readfds);FD_SET(sock, &readfds);maxfd = sock;while(!bexit){nready = select(maxfd+1, &readfds, NULL, NULL, NULL);if(nready < 0){perror("can select");break;}else if(nready == 0){continue;}/* data is ready */if(FD_ISSET(sock, &readfds)){can_recv_data(sock);}else { ; }}close(sock);pthread_detach(pthread_self());pthread_exit(0);
}// 初始化CAN0和CAN1设备，并创建两个接收数据处理线程
static void can_sock_init()
{pthread_t tid;can0_sock = can_open("can0");if(can0_sock < 0)return ;can1_sock = can_open("can1");if(can1_sock < 0)return ;if (0 != pthread_create(&tid, NULL, can_proc_start, (void *)&can0_sock)){return ;}if (0 != pthread_create(&tid, NULL, can_proc_start, (void *)&can1_sock)){return ;}can1_id = MASTR_CAN1_ID;can2_id = MASTR_CAN2_ID;printf("can open sucess can0_sock:%d, can1_sock:%d\n", can0_sock, can1_sock);
}int main(int argc, char *argv[])
{char *send_data = "hello,can!";signal(SIGINT, signal_handler);signal(SIGPIPE, signal_handler);signal(SIGTERM, signal_handler);can_sock_init(); // 初始化CAN0和CAN1设备数据，并创建接收线程do {sleep(1);can_send_data(CAN_1, (unsigned char *)send_data, strlen(send_data) - 1);} while (!bexit);return 0;
}

测试程序主要实现了如下功能：

建立两个接收数据线程接收CAN设备的数据并打印CAN网络上的数据。
通过CAN0设备定时1秒发送一串"hello,can!"数据到CAN网络。

3. 运行并验证程序功能。

PC上使用CAN分析工具按下图接好线
编辑

打开CAN调试软件，配置成500kbps的速率并打开设备，如下：
编辑
使用CAN调试软件给设备发送数据，如下：
编辑

将编译好的程序上传到板子上并运行，以下是正常收到数据后程序的打印信息：

root@ok113i:/home/forlinx# ./can_test 
can open sucess can0_sock:3, can1_sock:4
## PC往CAN0口发送测试数据接收打印
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN0 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
## PC往CAN1 口发送测试数据接收打印
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55 
CAN1 dlc = 6, can_id = 201
data:0x30 0x31 0x32 0x33 0x34 0x55

测试程序工程结构

├── build # 编译目录
├── can_apply.c                           # CAN 操作简单封装C源码
├── can_apply.h                           # CAN 操作简单封装头文件 
├── CMakeLists.txt                      # cmake 编译规则文件
├── cross-t113-i.cmake               # CMake嵌入式交叉编译工具链文件
└── main.c                                   # 测试程序主体源代码

工程源代码编译

cd build
cmake .. -DCMAKE_TOOLCHAIN_FILE=../cross-t113-i.cmake
make
Scanning dependencies of target can_test
[ 33%] Building C object CMakeFiles/can_test.dir/main.c.o
[ 66%] Building C object CMakeFiles/can_test.dir/can_apply.c.o
[100%] Linking C executable can_test
[100%] Built target can_test

工程使用cmake进行编译，需要注意的是要根据实际情况修改cross-t113-i.cmake中的GCC交叉编译工具的路径。

#
# CMake Toolchain file for crosscompiling on ARM.
#
# This can be used when running cmake in the following way:
#  cd build-t113/
#  cmake .. -DCMAKE_TOOLCHAIN_FILE=../cross-t113-i.cmake
#  orset(CROSS_PATH /home/luoyang/Dev/sdk/T113-i/OK113i-linux-sdk/out/t113_i/ok113i/longan/buildroot/host)# Target operating system name.
set(CMAKE_SYSTEM_NAME Linux)set (CMAKE_C_FLAGS "-std=gnu11" CACHE STRING "Set C Compiler Flags" FORCE)# Name of C compiler.
set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-gnueabi-gcc")
set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-gnueabi-g++")set (CMAKE_C_FLAGS "-std=gnu11 -mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4 -mno-unaligned-access -fno-aggressive-loop-optimizations -ffunction-sections" CACHE STRING "Set C Compiler Flags" FORCE)
set (CMAKE_CXX_FLAGS "-mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4 -mno-unaligned-access -fno-aggressive-loop-optimizations -ffunction-sections" CACHE STRING "Set C++ Compiler Flags" FORCE)# link flags
set(CMAKE_LINK_FLAGS "${CMAKE_LINK_FLAGS} -mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4 -mno-unaligned-access -fno-aggressive-loop-optimizations"  CACHE STRING "Set link Flags" FORCE)SET(CMAKE_SYSTEM_PROCESSOR "armv7-a_hardfp")add_definitions(-fPIC)
add_definitions(-DARMLINUX)
add_definitions(-D__gnu_linux__)# Where to look for the target environment. (More paths can be added here)
set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}/arm-buildroot-linux-gnueabi/sysroot")# Adjust the default behavior of the FIND_XXX() commands:
# search programs in the host environment only.
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)# Search headers and libraries in the target environment only.
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)