openwrt (linux）串口通信

1. 基本的串口通信程序。先读取内容，再将内容写回串口。

#include     <stdio.h>
#include     <stdlib.h>
#include     <unistd.h>
#include     <sys/types.h>
#include     <sys/stat.h>
#include     <fcntl.h>
#include     <termios.h>
#include     <errno.h>

main()
{
int fd;
int i;
int len;
int n = 0;
char read_buf[256];
char write_buf[256];
struct termios opt;

fd = open("/dev/ttyATH0", O_RDWR|O_NOCTTY|O_NDELAY);
if(fd == -1)
{
perror("open serial 0\n");
exit(0);
}

tcgetattr(fd, &opt);
bzero(&opt, sizeof(opt));

tcflush(fd, TCIOFLUSH);

cfsetispeed(&opt, B115200);
cfsetospeed(&opt, B115200);

opt.c_cflag &= ~CSIZE;
opt.c_cflag |= CS8;
opt.c_cflag &= ~CSTOPB;
opt.c_cflag &= ~PARENB;
opt.c_cflag &= ~CRTSCTS;
opt.c_cflag |= (CLOCAL | CREAD);

opt.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);

opt.c_oflag &= ~OPOST;

opt.c_cc[VTIME] = 0;
opt.c_cc[VMIN] = 0;

tcflush(fd, TCIOFLUSH);

printf("configure complete\n");

if(tcsetattr(fd, TCSANOW, &opt) != 0)
{
perror("serial error");
return -1;
}

printf("start send and receive data\n");

while(1)
{
n = 0;
len = 0;
bzero(read_buf, sizeof(read_buf));
bzero(write_buf, sizeof(write_buf));

while( (n = read(fd, read_buf, sizeof(read_buf))) > 0 )
{
for(i = len; i < (len + n); i++)
{
write_buf[i] = read_buf[i - len];
}
len += n;
}
write_buf[len] = '\0';

printf("Len %d \n", len);
printf("%s \n", write_buf);

n = write(fd, write_buf, len);
printf("write %d chars\n",n);

sleep(2);
}

}

2. 注意

opt.c_cc[VTIME] = 0;
opt.c_cc[VMIN] = 0;

在这两个值均为0 的情况下，read不管有没有数据都会立即返回。详细情况在linux下man tcsetattr.

如果不设定这两个值，那么read只有收到回车后才会读取缓存中的数据。

程序大部分转载自：/article/6540332.html

该链接的程序部分有误。