LINUX 简单的串口读写实例

#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 "string.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*/

#define FALSE -1

#define TRUE 0

/*********************************************************************/

int OpenDev(char *Dev)

{

int fd = open( Dev, O_RDWR | O_NOCTTY ); //| O_NOCTTY | O_NDELAY

if (-1 == fd)

{

perror("Can't Open Serial Port");

return -1;

}

else

return fd;

}

/**

*@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, };

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;

options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); /*Input*/

options.c_oflag &= ~OPOST; /*Output*/

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;

tcflush(fd,TCIFLUSH);

options.c_cc[VTIME] = 150; /* 设置超时15 seconds*/

options.c_cc[VMIN] = 0; /* Update the options and do it NOW */

if (tcsetattr(fd,TCSANOW,&options) != 0)

{

perror("SetupSerial 3");

return (FALSE);

}

return (TRUE);

}

int main(int argc, char **argv)

{

int fd;

int nread;

char buff[512];

char *dev = "/dev/ttyS0"; //串口二

fd = OpenDev(dev);

set_speed(fd,4800);

if (set_Parity(fd,8,1,'N') == FALSE)

{

printf("Set Parity Error/n");

exit (0);

}

int i;

i = getchar();

if ( i == '1')

{

while (1) //循环读取数据

{

while((nread = read(fd, buff, 512))>0)

{

printf("/nLen %d/n",nread);

buff[nread+1] = '/0';

printf( "/n%s", buff);

}

}

}

if ( i == '2')

{

while (1) //循环写入数据

{

gets(buff);

printf("------buff--->%s<--------/n",buff);

int num = strlen(buff);

printf("--------num---->%d<--------------/n",num);

if ( num > 0)

{

printf("Wirte num not NULL./r/n");

nread = write(fd, buff ,num);

if(nread == -1)

{

printf("Wirte sbuf error./n");

}

printf("--nread---->%d<-----------/n",nread);

}

}

}

close(fd);

//exit (0);

}