stserial_test.c

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#include     <stdio.h>      /*标准输入输出定义*/
#include     <stdlib.h>     /*标准函数库定义*/
#include     <unistd.h>     /*Unix标准函数定义*/
#include     <sys/types.h>  /**/
#include     <sys/stat.h>   /**/
#include     <fcntl.h>      /*文件控制定义*/
#include     <termios.h>    /*PPSIX终端控制定义*/
#include     <errno.h>      /*错误号定义*/
#include     <string.h>


#define FALSE 0
#define TRUE  1

/***@brief  设置串口通信速率
*@param  fd     类型 int  打开串口的文件句柄
*@param  speed  类型 int  串口速度
*@return  void*/

int speed_arr[] = { B38400, B19200, B9600, B4800, B2400, B1200, B300,
	    B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {38400,  19200,  9600,  4800,  2400,  1200,  300,
	    38400,  19200,  9600, 4800, 2400, 1200,  300, };

/*
 *	Function:		set_speed()
 *	Purpose: 		set the serial port buad rate
 *      Parameter:	fd - serial port handler
 *			speed - baud rate
 */

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 );
   }
}


/**
*@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;

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


/*
 *	Function:		OpenDev()
 * 	Purpose:		Open the serial port according the input parameter
 *	Parameter:	The device address
 */
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;
}


/*
 *	Function:		main()
 *      Purpose: 	Never stop story
 *	Parameter:	none
*/

int main(int argc, char **argv)
{
	int fd;
	int nread; 
	int nwrite;
	char buff[1024];
	char buff_char;
	char outbuf[ ] = "UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUSerial testUUUUUUUUUUUUUUUUUUUUUUUUUUUUU\r\n";
	char *dev ="/dev/ttyS2";

	fd = OpenDev(dev);	//open the serial port and return handler

				//if open success , set the baud rate
	if (fd>0)			
    		set_speed( fd , 115200 );		
	else
	{
		printf("Can't Open Serial Port!\n");
		exit(0);
	}
				//set attribute 			
  	if (set_Parity(fd,8,1,'N')== FALSE)	
  	{
    		printf("Set Parity Error\n");
    		exit(1);
  	}
	
				//main loop , never stop
  	while( 1 )
  	{
				//read from the serial port

   		while( (nread = read(fd, &buff_char, 1)) > 0 )
   		{
		//	printf(" read the char " );
      		//	printf("\nLen %d\n",nread);
	      	//	buff[nread+1]='\0';
      	//		printf("%c\n",buff_char);
	
			memset(outbuf, buff_char, 70);
			nwrite = write(fd, outbuf , strlen(outbuf));

   	 	}		

		//write char to the serial port
//		nwrite = write(fd, outbuf , 1024);

  	}
    close(fd);
    exit(0);
}