【MYD-JX8MMA7】 （四）CAN通讯理论

因为在经过两天的时间研究can通讯发现，can通讯存在问题，后咨询厂家技术，厂家技术表示此板子系统里没有配置can通讯相关内容。所以一下是理论内容

一、硬件电路

1、CAN-IO

首先是查硬件用户手册，板载没有CAN通讯芯片，所以需要查下预留的CAN通讯接口，还可查看原理图，找到CAN通讯接口，还需要找到供电电源。

2、CAN硬件电路

CAN硬件电路是一个比较标准的电路，在这里使用的是NXP1042CAN通讯芯片。

3、CAN分析仪

CAN分析仪用于电脑和开发板通讯的测试使用，在此使用的是创新科技的CAN分析仪。国产CAN分析仪虽然稳定性不够好，但是很实惠啊。

二、软件代码

1.代码文件.c

#include <can_config.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <signal.h>

#include <libgen.h>

#include <getopt.h>

#include <limits.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/uio.h>

#include <sys/ioctl.h>

#include <net/if.h>

#include <linux/can.h>

#include <linux/can/raw.h>

extern int optind, opterr, optopt;

static int running = 1;

enum {

VERSION_OPTION = CHAR_MAX + 1,

};

void print_usage(char *prg)

{

fprintf(stderr, "Usage: %s [] [Options]\n"

"\n"

"Send all messages received on to \n"

"If is omitted, then <can_interface> is used for sending\n"

"\n"

"Options:\n"

" -f, --family=FAMILY Protocol family (default PF_CAN = %d)\n"

" -t, --type=TYPE Socket type, see man 2 socket (default SOCK_RAW = %d)\n"

" -p, --protocol=PROTO CAN protocol (default CAN_RAW = %d)\n"

" -v, --verbose be verbose\n"

" -h, --help this help\n"

" --version print version information and exit\n",

prg, PF_CAN, SOCK_RAW, CAN_RAW);

}

void sigterm(int signo)

{

running = 0;

}

int main(int argc, char **argv)

{

struct can_frame frame;

struct ifreq ifr[2];

struct sockaddr_can addr[2];

char *intf_name[2];

int family = PF_CAN, type = SOCK_RAW, proto = CAN_RAW;

int nbytes, i, out;

int opt;

int s[2];

int verbose = 0;

signal(SIGTERM, sigterm);
signal(SIGHUP, sigterm);
signal(SIGINT, sigterm);

struct option long_options[] = {
	{ "help", no_argument, 0, 'h' },
	{ "family", required_argument, 0, 'f' },
	{ "protocol", required_argument, 0, 'p' },
	{ "type", required_argument, 0, 't' },
	{ "version", no_argument, 0, VERSION_OPTION},
	{ "verbose", no_argument, 0, 'v'},
	{ 0, 0, 0, 0},
};

while ((opt = getopt_long(argc, argv, "hf:t:p:v", long_options, NULL)) != -1) {
	switch (opt) {
	case 'f':
		family = atoi(optarg);
		break;

	case 't':
		type = atoi(optarg);
		break;

	case 'p':
		proto = atoi(optarg);
		break;

	case 'v':
		verbose = 1;
		break;

	case 'h':
		print_usage(basename(argv[0]));
		exit(0);

	case VERSION_OPTION:
		printf("version : %s\\n", VERSION);
		exit(0);

	default:
		fprintf(stderr, "Unknown option %c\\n", opt);
		break;
	}
}

if (optind == argc) {
	print_usage(basename(argv[0]));
	exit(0);
}

intf_name[0] = argv[optind++];
if (optind == argc)
	intf_name[1] = intf_name[0];
else
	intf_name[1] = argv[optind];

printf("interface-in = %s, interface-out = %s, family = %d, type = %d, proto = %d\\n",
       intf_name[0], intf_name[1], family, type, proto);

if (intf_name[0] == intf_name[1])
	out = 0;
else
	out = 1;

for (i = 0; i <= out; i++) {
	if ((s[i] = socket(family, type, proto)) < 0) {
		perror("socket");
		return 1;
	}

	addr[i].can_family = family;
	strcpy(ifr[i].ifr_name, intf_name[i]);
	ioctl(s[i], SIOCGIFINDEX, &ifr[i]);
	addr[i].can_ifindex = ifr[i].ifr_ifindex;

	if (bind(s[i], (struct sockaddr *)&addr[i], sizeof(addr)) < 0) {
		perror("bind");
		return 1;
	}
}

while (running) {
	if ((nbytes = read(s[0], &frame, sizeof(frame))) < 0) {
		perror("read");
		return 1;
	}
	if (verbose) {
		printf("%04x: ", frame.can_id);
		if (frame.can_id & CAN_RTR_FLAG) {
			printf("remote request");
		} else {
			printf("[%d]", frame.can_dlc);
			for (i = 0; i < frame.can_dlc; i++) {
				printf(" %02x", frame.data[i]);
			}
		}
		printf("\\n");
	}
	frame.can_id++;
	write(s[out], &frame, sizeof(frame));
}

return 0;

}

2.代码文件.h

/* include/can_config.h. Generated from can_config.h.in by configure. */

/* include/can_config.h.in. Generated from configure.ac by autoheader. */

/* debugging */

/* #undef DEBUG */

/* Define to 1 if you have the <dlfcn.h> header file. */

#define HAVE_DLFCN_H 1

/* Define to 1 if you have the <fcntl.h> header file. */

#define HAVE_FCNTL_H 1

/* Define to 1 if you have the <inttypes.h> header file. */

#define HAVE_INTTYPES_H 1

/* Define to 1 if you have the <limits.h> header file. */

#define HAVE_LIMITS_H 1

/* Define to 1 if you have the <memory.h> header file. */

#define HAVE_MEMORY_H 1

/* Define to 1 if you have the `socket' function. */

#define HAVE_SOCKET 1

/* Define to 1 if `stat' has the bug that it succeeds when given the

zero-length file name argument. */

#define HAVE_STAT_EMPTY_STRING_BUG 1

/* Define to 1 if you have the <stdint.h> header file. */

#define HAVE_STDINT_H 1

/* Define to 1 if you have the <stdlib.h> header file. */

#define HAVE_STDLIB_H 1

/* Define to 1 if you have the `strchr' function. */

#define HAVE_STRCHR 1

/* Define to 1 if you have the <strings.h> header file. */

#define HAVE_STRINGS_H 1

/* Define to 1 if you have the <string.h> header file. */

#define HAVE_STRING_H 1

/* Define to 1 if you have the `strtoul' function. */

#define HAVE_STRTOUL 1

/* Define to 1 if you have the <sys/ioctl.h> header file. */

#define HAVE_SYS_IOCTL_H 1

/* Define to 1 if you have the <sys/socket.h> header file. */

#define HAVE_SYS_SOCKET_H 1

/* Define to 1 if you have the <sys/stat.h> header file. */

#define HAVE_SYS_STAT_H 1

/* Define to 1 if you have the <sys/types.h> header file. */

#define HAVE_SYS_TYPES_H 1

/* Define to 1 if you have the <unistd.h> header file. */

#define HAVE_UNISTD_H 1

/* Define to 1 if `lstat' dereferences a symlink specified with a trailing

slash. */

#define LSTAT_FOLLOWS_SLASHED_SYMLINK 1

/* Define as the return type of signal handlers (int' or void'). */

#define RETSIGTYPE void

/* Define to 1 if you have the ANSI C header files. */

#define STDC_HEADERS 1

/* Version number of package */

#define VERSION "1.0"

/* Define for Solaris 2.5.1 so the uint32_t typedef from <sys/synch.h>,

<pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the

#define below would cause a syntax error. */

/* #undef _UINT32_T */

/* Define to empty if `const' does not conform to ANSI C. */

/* #undef const */

/* Define to `unsigned int' if <sys/types.h> does not define. */

/* #undef size_t */

/* Define to `int' if <sys/types.h> does not define. */

/* #undef ssize_t */

/* Define to the type of an unsigned integer type of width exactly 32 bits if

such a type exists and the standard includes do not define it. */

/* #undef uint32_t */

3.makefile文件

source /home/jack/omapl138/ti/mcsdk_1_01_00_02/linux-devkit/environment-setup

#CC = gcc

CFLAGS = -Wall -g

INCLUDES = -I.

LDFLAGS =

VPATH = .

OBJS = tl_can_echo.o

TARGETS = tl_can_echo

all : $(TARGETS)

tl_can_echo: $(OBJS)
(CC) -o @ **^ **(LDFLAGS)

%.o:%.c
(CC) -c < -o **@ **(INCLUDES) $(CFLAGS)

.PHONY:

clean:

rm -f $(TARGETS) *.o