imx6ul下的串口配置及通信

imx6ul下的串口配置及通信

注：使用的开发板为米尔科技的MYS-6ULX-IND.

一、设备树的配置

以UART2配置为例，下面UART2的寄存器寄存器选择默认：

pinctrl_uart2: uart2grp {
			fsl,pins = <
				MX6UL_PAD_UART2_TX_DATA__UART2_DCE_TX	0x1b0b1
				MX6UL_PAD_UART2_RX_DATA__UART2_DCE_RX	0x1b0b1
			>;
		};

下面这部分代码需要稍作修改：

&uart2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart2>;
	/*fsl,uart-has-rtscts;*/
	/* for DTE mode, add below change */
	/* fsl,dte-mode; */
	/* pinctrl-0 = <&pinctrl_uart2dte>; */
	status = "disabled";
};

修改为：

&uart2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart2>;
	/*fsl,uart-has-rtscts;*/
	/* for DTE mode, add below change */
	/* fsl,dte-mode; */
	/* pinctrl-0 = <&pinctrl_uart2dte>; */
	status = okay";
};

二、imx6ul UART2的引脚

三、示例代码

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define FALSE 1
#define TRUE 0

char *recchr="We received:\"";

void print_usage();

int speed_arr[] = { 
	B921600, B460800, B230400, B115200, B57600, B38400, B19200, 
	B9600, B4800, B2400, B1200, B300, 
};

int name_arr[] = {
	921600, 460800, 230400, 115200, 57600, 38400,  19200,  
	9600,  4800,  2400,  1200,  300,  
};

void set_speed(int fd, int speed)
{
	int   i;
	int   status;
	struct termios   Opt;
	tcgetattr(fd, &Opt);

	for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++) {
		if  (speed == name_arr[i])	{
			tcflush(fd, TCIOFLUSH);
			cfsetispeed(&Opt, speed_arr[i]);
			cfsetospeed(&Opt, speed_arr[i]);
			status = tcsetattr(fd, TCSANOW, &Opt);
			if  (status != 0)
				perror("tcsetattr fd1");
				return;
		}
		tcflush(fd,TCIOFLUSH);
  	 }

	if (i == 12){
		printf("\tSorry, please set the correct baud rate!\n\n");
	}
}
/*
	*@brief   设置串口数据位，停止位和效验位
	*@param  fd     类型  int  打开的串口文件句柄*
	*@param  databits 类型  int 数据位   取值 为 7 或者8*
	*@param  stopbits 类型  int 停止位   取值为 1 或者2*
	*@param  parity  类型  int  效验类型 取值为N,E,O,,S
*/
int set_Parity(int fd,int databits,int stopbits,int parity)
{
	struct termios options;
	if  ( tcgetattr( fd,&options)  !=  0) {
		perror("SetupSerial 1");
		return(FALSE);
	}
	options.c_cflag &= ~CSIZE ;
	switch (databits) /*设置数据位数*/ {
	case 7:
		options.c_cflag |= CS7;
	break;
	case 8:
		options.c_cflag |= CS8;
	break;
	default:
		fprintf(stderr,"Unsupported data size\n");
		return (FALSE);
	}
	
	switch (parity) {
	case 'n':
	case 'N':
		options.c_cflag &= ~PARENB;   /* Clear parity enable */
		options.c_iflag &= ~INPCK;     /* Enable parity checking */
	break;
	case 'o':
	case 'O':
		options.c_cflag |= (PARODD | PARENB);  /* 设置为奇效验*/
		options.c_iflag |= INPCK;             /* Disnable parity checking */
	break;
	case 'e':
	case 'E':
		options.c_cflag |= PARENB;     /* Enable parity */
		options.c_cflag &= ~PARODD;   /* 转换为偶效验*/ 
		options.c_iflag |= INPCK;       /* Disnable parity checking */
	break;
	case 'S':	
	case 's':  /*as no parity*/
		options.c_cflag &= ~PARENB;
		options.c_cflag &= ~CSTOPB;
	break;
	default:
		fprintf(stderr,"Unsupported parity\n");
		return (FALSE);
	}
 	/* 设置停止位*/  
  	switch (stopbits) {
   	case 1:
    	options.c_cflag &= ~CSTOPB;
  	break;
 	case 2:
  		options.c_cflag |= CSTOPB;
  	break;
 	default:
  		fprintf(stderr,"Unsupported stop bits\n");
  		return (FALSE);
 	}
  	/* Set input parity option */
  	if (parity != 'n')
    	options.c_iflag |= INPCK;
  	options.c_cc[VTIME] = 150; // 15 seconds
    	options.c_cc[VMIN] = 0;

	options.c_lflag &= ~(ECHO | ICANON);

  	tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */
  	if (tcsetattr(fd,TCSANOW,&options) != 0) {
    	perror("SetupSerial 3");
  		return (FALSE);
 	}
	return (TRUE);
}

/**
	*@breif 打开串口
*/
int OpenDev(char *Dev)
{
	int fd = open( Dev, O_RDWR );         //| O_NOCTTY | O_NDELAY
 	if (-1 == fd) { /*设置数据位数*/
   		perror("Can't Open Serial Port");
   		return -1;
	} else
		return fd;
}



/*
	*@breif  main()
 */
int main(void)
{
	int  fd;
	char *device = "/dev/ttymxc1";
	int nread;			/* Read the counts of data */
	char buff[512];		/* Recvice data buffer */
	char *xmit = "1234567890"; /* Default send data */ 

	fd = OpenDev(device);

	if (fd > 0) {
		set_speed(fd, 115200);
	} else {
		fprintf(stderr, "Error opening %s: %s\n", device, strerror(errno));
		exit(1);
	}

	if (set_Parity(fd,8,1,'N')== FALSE) {
		fprintf(stderr, "Set Parity Error\n");
		close(fd);
		exit(1);
	}
	
	//发送数据测试	
	printf("%s SEND: %s\n",device, xmit);
	write(fd, xmit, strlen(xmit));
		
		
    //接收数据测试
    while(1) {
    	nread = read(fd, buff, sizeof(buff));
    	if (nread > 0) {
    		buff[nread] = '\0';
    		printf("%s RECV[%d]: %s\n", device, nread, buff);
			break;
    	}
    }
	
	close(fd);
	exit(0);
}