嵌入式linux操作串口简单示例

嵌入式linux操作串口简单示例

这里以MT7688 openwrt系列为例
main.c

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

//打开串口文件
static int open_uart(void)
{
    
    
    long vdisable;
    int fd;

    fd = open("/dev/ttyS1", O_RDWR|O_NOCTTY|O_NDELAY);//注意你的设备名
    if (-1 == fd)
    {
    
    
        perror("Can't Open Serial Port");
        return(-1);
    }

    return fd;
}

//配置串口参数 波特率 数据位 校验位 停止位
static int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{
    
    
    struct termios newtio, oldtio;

    if ( tcgetattr( fd,&oldtio) != 0)
    {
    
    
        printf("SetupSerial 1");
        return -1;
    }
    bzero( &newtio, sizeof( newtio ) );
    newtio.c_cflag |= CLOCAL | CREAD;
    newtio.c_cflag &= ~CSIZE;

    switch( nBits )
    {
    
    
		case 7:
			newtio.c_cflag |= CS7;
			break;
		case 8:
			newtio.c_cflag |= CS8;
			break;
    }

    switch( nEvent )
    {
    
    
		case 'O':
			newtio.c_cflag |= PARENB;
			newtio.c_cflag |= PARODD;
			newtio.c_iflag |= (INPCK | ISTRIP);
			break;
		case 'E':
			newtio.c_iflag |= (INPCK | ISTRIP);
			newtio.c_cflag |= PARENB;
			newtio.c_cflag &= ~PARODD;
			break;
		case 'N':
			newtio.c_cflag &= ~PARENB;
			break;
    }
    switch( nSpeed )
    {
    
    
		case 2400:
			cfsetispeed(&newtio, B2400);
			cfsetospeed(&newtio, B2400);
			break;
		case 4800:
			cfsetispeed(&newtio, B4800);
			cfsetospeed(&newtio, B4800);
			break;
		case 9600:
			cfsetispeed(&newtio, B9600);
			cfsetospeed(&newtio, B9600);
			break;
		case 115200:
			cfsetispeed(&newtio, B115200);
			cfsetospeed(&newtio, B115200);
			break;
		default:
			cfsetispeed(&newtio, B9600);
			cfsetospeed(&newtio, B9600);
			break;
    }
    if ( nStop == 1 )
    {
    
    
        newtio.c_cflag &= ~CSTOPB;
    }
    else if ( nStop == 2 )
    {
    
    
        newtio.c_cflag |= CSTOPB;
    }
    newtio.c_cc[VTIME] = 0;
    newtio.c_cc[VMIN]  = 0;
    tcflush(fd,TCIFLUSH);
    if ((tcsetattr(fd,TCSANOW,&newtio))!=0)
    {
    
    
        printf("com set error");
        return -1;
    }

    return 0;
}

int main(void)
{
    
    
	int fd;
	char buffer[256]={
    
    0};

	fd = open_uart();//打开串口
	set_opt(fd,115200,8,'N',1);//配置串口参数 波特率 数据位8 校验无 停止位1位

	printf("serial opened,wait rcv\n");//打印提示语

	while(1)
	{
    
    
			memset(buffer,0,256);//接收数组清零
			while (read(fd,buffer,sizeof(buffer)) == 0);//等待电脑串口调试助手发送数据
			printf("rcved %s\n",buffer);//将收到的数据打印出来
			write(fd,buffer,strlen(buffer));//将收到的数据发送回去

	}
	close(fd);//关闭串口

	return 0;
}