scomm.cpp

linux下的串口测试程序

#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/select.h>
#include <errno.h>      /*错误号定义*/
#include <stdio.h>
#include <string.h>
#include "scomm.h"

#define CMSPAR    010000000000
#undef  STOPBIT_MARK

scomm::scomm() 
{
	_fd = -1;
}

scomm::~scomm()
{
	close();
}

int scomm::open(const char *dev)
{
	strcpy(_device, dev);
	
	if (_fd >= 0)
		close();

	int fd = ::open(_device, O_RDWR | O_NOCTTY);
	if (fd < 0)
		return -1;

	_fd = fd;

	return 0;
}

int scomm::close()
{
	if (_fd >= 0) {
		::close(_fd);
		_fd = -1;
	}
	return 0;
}

int scomm::read(void *buf, int size, int timeout)
{
	if(timeout<0)
		return _fd >= 0 ? ::read(_fd, buf, size) : -1;
	int            n;
	fd_set         input;
	struct timeval tv;

	/* Initialize the input set */
	FD_ZERO(&input);
	FD_SET(_fd, &input);

	/* Initialize the timeout structure */
	tv.tv_sec  = timeout/1000;
	tv.tv_usec = (timeout%1000)*1000;

	/* Do the select */
	n = select(_fd + 1,  &input, NULL, NULL, &tv);

	/* See if there was an error */
	if(n<=0)
		return n;

	/* We have input */
	if (FD_ISSET(_fd, &input))
		return ::read(_fd, buf, size);
	return -1;
}

static int speed_arr[] = { B115200, B57600, B38400, B19200, B9600, B4800, B2400, B1200, B300,};
static int name_arr[] =  { 115200,  57600,  38400,  19200,  9600,  4800,  2400,  1200,  300,};
void scomm::set_baud(int baud)
{
	int   i;
	struct termios   Opt;
	tcgetattr(_fd, &Opt);

	int   baud_count = sizeof(speed_arr) / sizeof(int);
	for ( i= 0;  i <baud_count ;  i++){
		if  (baud == name_arr[i]){
			tcflush(_fd, TCIOFLUSH);
			cfsetispeed(&Opt, speed_arr[i]);
			cfsetospeed(&Opt, speed_arr[i]);
			break;
		}
	}
	// Local Options (Choosing Raw Input)
	Opt.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
	
	Opt.c_iflag = IGNPAR;

	// Setting Software Flow Control
	Opt.c_iflag &= ~(IXON | IXOFF | IXANY);
	
	// Choosing Raw Output
	Opt.c_oflag  &= ~OPOST;   /*Output*/
	
	// Setting Read Timeouts
	Opt.c_cc[VMIN] = 0;
	Opt.c_cc[VTIME] = 10; // 1 seconds

	tcflush(_fd,TCIFLUSH); /* Update the options and do it NOW */
	if (tcsetattr(_fd,TCSANOW,&Opt) != 0){
		perror("tcsetattr fd1");
		return;
	}
}

/**
*@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,M,S
*/
bool scomm::set_parity(int parity,int databits,int stopbits)
{
	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 &= ~CMSPAR;
		options.c_cflag &= ~PARENB;   /* Clear parity enable */
		break;
	case 'o':
	case 'O':
		options.c_cflag &= ~CMSPAR;
		options.c_cflag |= (PARODD | PARENB);  /* 设置为奇效验*/ 
		break;
	case 'e':
	case 'E':
		options.c_cflag &= ~CMSPAR;
		options.c_cflag |= PARENB;     /* Enable parity */
		options.c_cflag &= ~PARODD;   /* 转换为偶效验*/  
		break;
	case 'S':
	case 's':
#ifndef STOPBIT_MARK
		options.c_cflag &= ~PARODD;
#endif
		options.c_cflag |= PARENB | CMSPAR;
		break;
	case 'M':
	case 'm': 
		options.c_cflag |= PARENB | CMSPAR |PARODD;
#ifdef STOPBIT_MARK
		stopbits = 2;
#endif
		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' || parity == 'N')
		options.c_iflag &= ~INPCK;     /* Enable parity checking */
	else
		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;
}

// vim: ts=4 sw=4 cindent