linux 串口调试（UART serial ttyS）

短命女 2022-09-04 09:56 628阅读 0赞

## 一、设备树下开启串口 ##

路径：kernel\\arch\\arm\\boot\\dts下的对应dts文件  
例如：

&uart4{ 
        pinctrl-names = "default";
      pinctrl-0 = <&uart4m1_xfer>;
      status = "okay";
    };

## 二、查看嵌入式设备是否成功挂载串口 ##

/dev/ 路径下有：ttyS\*

## 三、交叉编译 测试程序 uart\_comm.c ##

执行 arm-linux-gnueabihf-gcc uart\_comm.c -o uart\_comm

## 四、拷贝uart\_comm到嵌入式设备，然后执行 ./uart\_comm ##

## 五、嵌入式设备通过USB转串口接到电脑，打开串口调试工具测试 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNzc4NzA0Mw_size_16_color_FFFFFF_t_70]  
直接上代码：

//示例代码 文件名：uart_comm.c
    #include <stdio.h>
    #include <string.h>
    #include <unistd.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <termios.h>
    #include <errno.h>
    
    int set_opt(int, int, int, char, int);
    void main()
    { 
    	int fd, nByte, flag = 1;
    	char *uart4 = "/dev/ttyS4";
    	char buffer[512];
    	char *uart_out = "Please input,waiting....\r\n";
    	char *uart_demo = "Linux uart demo\r\n";
    	int i;
    
    	memset(buffer, 0, sizeof(buffer));
    	//if((fd = open(uart4, O_RDWR|O_NOCTTY))<0)//默认为阻塞读方式
    	if ((fd = open(uart4, O_RDWR | O_NONBLOCK)) < 0) //非阻塞读方式
    		printf("open %s is failed", uart4);
    	else
    	{ 
    		set_opt(fd, 115200, 8, 'N', 1);
    		write(fd, uart_demo, strlen(uart_demo));
    		write(fd, uart_out, strlen(uart_out));
    		while (1)
    		{ 
    			write(fd, uart_demo, strlen(uart_demo));
    			write(fd, uart_out, strlen(uart_out));
    			memset(buffer, 0, sizeof(buffer));
    			while ((nByte = read(fd, buffer, 512)) > 0)
    			{ 
    				buffer[nByte + 1] = '\0';
    				printf("%s\r\n", buffer);
    				write(fd, buffer, strlen(buffer));
    				memset(buffer, 0, strlen(buffer));
    				nByte = 0;
    			}
    			sleep(1);
    			printf("send date.\r\n");
    		}
    	}
    }
    
    int set_opt(int fd, int nSpeed, int nBits, char nEvent, int nStop)
    { 
    	struct termios newtio, oldtio;
    	if (tcgetattr(fd, &oldtio) != 0)
    	{ 
    		perror("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;
    	case 460800:
    		cfsetispeed(&newtio, B460800);
    		cfsetospeed(&newtio, B460800);
    		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] = 100; ///* 设置超时10 seconds*/
    	newtio.c_cc[VMIN] = 0;
    	tcflush(fd, TCIFLUSH);
    	if ((tcsetattr(fd, TCSANOW, &newtio)) != 0)
    	{ 
    		perror("com set error");
    		return -1;
    	}
    
    	// printf("set done!\n\r");
    	return 0;
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNzc4NzA0Mw_size_16_color_FFFFFF_t_70]: /images/20220829/05034ae6c4dd4c968fef8dc9b4820850.png