imx6ul usb转串口调试（代码）

蔚落 2022-12-30 04:59 337阅读 0赞

这里需要注意的是，当usb转串口模块插到usb上面/dev下面才能有设备，拔了设备就没了，所以操作的时候要注意。

#include <stdio.h>        //标准输入输出,如printf、scanf以及文件操作
    #include <stdlib.h>        //标准库头文件，定义了五种类型、一些宏和通用工具函数
    #include <unistd.h>        //定义 read write close lseek 等Unix标准函数
    #include <sys/types.h>    //定义数据类型，如 ssiz e_t off_t 等
    #include <sys/stat.h>    //文件状态
    #include <fcntl.h>        //文件控制定义
    #include <termios.h>    //终端I/O
    #include <errno.h>        //与全局变量 errno 相关的定义
    #include <getopt.h>        //处理命令行参数
    #include <string.h>        //字符串操作
    #include <time.h>        //时间
    #include <sys/select.h>    //select函数
    
    
    #include <sys/ioctl.h>
    #include <net/if.h>
    #include <pthread.h>
    
    
    int usb2uartfd;
    
    
    int setOpt(int fd, int nSpeed, int nBits, int nParity, int nStop)
    {
        struct termios newtio, oldtio;
    
        // 保存测试现有串口参数设置，在这里如果串口号等出错，会有相关的出错信息
        if (tcgetattr(fd, &oldtio) != 0)
        {
            perror("SetupSerial 1");
            return -1;
        }
    
        bzero(&newtio, sizeof(newtio));        //新termios参数清零
        newtio.c_cflag |= CLOCAL | CREAD;    //CLOCAL--忽略 modem 控制线,本地连线, 不具数据机控制功能, CREAD--使能接收标志
        // 设置数据位数
        newtio.c_cflag &= ~CSIZE;    //清数据位标志
        switch (nBits)
        {
            case 7:
                newtio.c_cflag |= CS7;
            break;
            case 8:
                newtio.c_cflag |= CS8;
            break;
            default:
                fprintf(stderr, "Unsupported data size\n");
                return -1;
        }
        // 设置校验位
        switch (nParity)
        {
            case 'o':
            case 'O':                     //奇校验
                newtio.c_cflag |= PARENB;
                newtio.c_cflag |= PARODD;
                newtio.c_iflag |= (INPCK | ISTRIP);
                break;
            case 'e':
            case 'E':                     //偶校验
                newtio.c_iflag |= (INPCK | ISTRIP);
                newtio.c_cflag |= PARENB;
                newtio.c_cflag &= ~PARODD;
                break;
            case 'n':
            case 'N':                    //无校验
                newtio.c_cflag &= ~PARENB;
                break;
            default:
                fprintf(stderr, "Unsupported parity\n");
                return -1;
        }
        // 设置停止位
        switch (nStop)
        {
            case 1:
                newtio.c_cflag &= ~CSTOPB;
            break;
            case 2:
                newtio.c_cflag |= CSTOPB;
            break;
            default:
                fprintf(stderr,"Unsupported stop bits\n");
                return -1;
        }
        // 设置波特率 2400/4800/9600/19200/38400/57600/115200/230400
        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 19200:
                cfsetispeed(&newtio, B19200);
                cfsetospeed(&newtio, B19200);
                break;
            case 38400:
                cfsetispeed(&newtio, B38400);
                cfsetospeed(&newtio, B38400);
                break;
            case 57600:
                cfsetispeed(&newtio, B57600);
                cfsetospeed(&newtio, B57600);
                break;
            case 115200:
                cfsetispeed(&newtio, B115200);
                cfsetospeed(&newtio, B115200);
                break;
            case 230400:
                cfsetispeed(&newtio, B230400);
                cfsetospeed(&newtio, B230400);
                break;
            default:
                printf("\tSorry, Unsupported baud rate, set default 9600!\n\n");
                cfsetispeed(&newtio, B9600);
                cfsetospeed(&newtio, B9600);
                break;
        }
        // 设置read读取最小字节数和超时时间
        newtio.c_cc[VTIME] = 1;     // 读取一个字符等待1*(1/10)s
        newtio.c_cc[VMIN] = 1;        // 读取字符的最少个数为1
    
    	tcflush(fd,TCIFLUSH);         //清空缓冲区
    	if (tcsetattr(fd, TCSANOW, &newtio) != 0)    //激活新设置
    	{
    		perror("SetupSerial 3");
    		return -1;
    	}
    	printf("Serial set done!\n");
        return 0;
    }
    
    
    
    void usb2uartfdCreate()
    {
    	int ret = 0;
    	
    	usb2uartfd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
    	if(usb2uartfd < 0)
    	{
    		printf("usb uart open failed ret = %d\r\n",usb2uartfd);
    		usb2uartfd = -1;
    		return;
    	}
    	
    	ret = fcntl(usb2uartfd, F_SETFL, 0);
    	if(ret < 0)
    	{
    		printf("fcntl failed ret = %d\r\n",ret);
    		close(usb2uartfd);
    		usb2uartfd = -1;
    		return;
    	}
    	
    	if (isatty(usb2uartfd) == 0)
    	{
    		printf("standard input is not a terminal device\r\n");
    		close(usb2uartfd);
    		usb2uartfd = -1;
    		return;	
    	}
    	
    	if (setOpt(usb2uartfd, 115200, 8, 'N', 1)== -1)    //设置8位数据位、1位停止位、无校验
    	{
    		printf("Set opt Error\r\n");
    		close(usb2uartfd);
    		usb2uartfd = -1;
    		return ;				
    	}
    	
    	tcflush(usb2uartfd, TCIOFLUSH);    //清掉串口缓存
    	fcntl(usb2uartfd, F_SETFL, 0);    //串口阻塞
    	
    	printf("uart fd create ok\r\n");
    }
    
    void *uartrecv(void *arg)
    {
    	unsigned int maxfd = 0;
    	unsigned int ret = 0;
    	struct timeval waittime;
    	fd_set rfd;
    	char buf[128];
    	
    	while(1)
    	{
    		FD_ZERO(&rfd);
    		
    		if(usb2uartfd == -1)
    			return NULL;
    		
    		FD_SET(usb2uartfd,&rfd);
    		if(maxfd < usb2uartfd)
    		{
    			maxfd = usb2uartfd;
    		}
    		
    		waittime.tv_sec = 1;
    		waittime.tv_usec = 0;
    		ret = select(maxfd + 1,&rfd,NULL,NULL,&waittime);
    		if(0 >= ret)
    		{
    			continue;
    		}
    		
    		if(FD_ISSET(usb2uartfd,&rfd))
    		{
    			memset(buf,0,sizeof(buf));
    			read(usb2uartfd,buf,sizeof(buf) - 1);
    			printf("usb uart recv buf = %s\r\n",buf);
    		}
    	}
    }
    
    
    
    
    void main()
    {
    	char buf[128];
    	pthread_t ntid;
    	
    	usb2uartfdCreate();
    		
    	pthread_create(&ntid, NULL, uartrecv, NULL);
    	
    	while(1)
    	{
    		if(usb2uartfd != -1)
    		{
    			memset(buf,0,sizeof(buf));
    			sprintf(buf,"this is usb uart send date");
    			write(usb2uartfd,buf,strlen(buf));
    			tcflush(usb2uartfd,TCOFLUSH);
    		}
    			
    		sleep(5);
    	}
    }