uart2.c

linux下的串口简单测试程序。实现打开串口

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
#include <termios.h>
#include <time.h>
#include <signal.h>
#include <sys/shm.h>
#include <asm/types.h>
#include <sys/ipc.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/time.h>

int 		  ComPort,CurrentPort;

int set_opt(int fd,int nSpeed,int nBits,char nEvent,int nStop)
{
	struct termios newtio,oldtio;
	//保存现有串口参数设置
	if(tcgetattr(fd,&oldtio)!=0) {
		perror("Setup Serial 1");
		return -1;
	}
	bzero(&newtio,sizeof(newtio));
	//设置该标志，才可以设置波特率，字符大小，数据位，停止位等参数
	newtio.c_cflag |= CLOCAL | CREAD;
	newtio.c_cflag &= ~CSIZE;
	//设置停止位
	switch(nBits) {
		case 7:
			newtio.c_cflag |=CS7;
			break;
		case 8:
			newtio.c_cflag |=CS8;
			break;
	}
	//设置奇偶校验位
	switch(nEvent) {
		case 'O':	//奇
			newtio.c_cflag |= PARENB;
			newtio.c_cflag |= PARODD;
			newtio.c_iflag |= (INPCK|ISTRIP);
		break;
		case 'E':	//偶
			newtio.c_iflag |= (INPCK|ISTRIP);
			newtio.c_cflag |= PARENB;
			newtio.c_cflag &= ~PARODD;
		break;
		case 'N':	//无校验
			newtio.c_cflag &= ~PARENB;
		break;
	}
	//设置波特率
	switch(nSpeed) {
		case 300:
			cfsetispeed(&newtio,B300);
			cfsetospeed(&newtio,B300);
		break;
		case 600:
			cfsetispeed(&newtio,B600);
			cfsetospeed(&newtio,B600);
		break;
		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;
		default:
			cfsetispeed(&newtio,B9600);
			cfsetospeed(&newtio,B9600);
		break;
	}
	//设置停止位
	if(nStop ==1) {
		newtio.c_cflag &= ~CSTOPB;
	}else if(nStop==2) {
		newtio.c_cflag |= CSTOPB;
	}
	//设置等待时间和最小接收字符
	newtio.c_cc[VTIME]=0;
	newtio.c_cc[VMIN]=0;
	//处理未接收字符
	tcflush(fd,TCIFLUSH);
	//激活新配置
	if((tcsetattr(fd,TCSANOW,&newtio))!=0) {
		perror("com set error");
		return -1;
	}
//	fprintf(stderr,"set done!\n");
	return 0;
}

int main(int argc, char *argv[])
{
	char			com[16],pnum[2];
	char			buff[]="Hello\n";
	int				ret=0,i,nwrite;
	int				val;

	//打开串口设备
	CurrentPort = 1;
  	if (argc > 1) {
  	  	CurrentPort = atoi(argv[1]);
  	  	if(CurrentPort>255)
  	  		CurrentPort=1;
  	}

  	memset(com, 0, sizeof(com));
  	strcpy(com, "/dev/ttyS");
//  	itoa(CurrentPort, pnum, 10);
	memset(pnum,0,sizeof(pnum));
	sprintf(pnum,"%d",CurrentPort);
  	strcat(com, pnum);
  	fprintf(stderr,"port=%d,dev=%s\n",CurrentPort,com);

  	ComPort = open(com, O_RDWR|O_NOCTTY|O_NDELAY);
  	if (ComPort < 0 ) {
  		fprintf(stderr, "Open %s error!\n",com);
  		exit(1);
  	}
  	//恢复串口为阻塞状态
  	if(fcntl(ComPort,F_SETFL,0)<0)
  		printf("fcntl failed\n");
  	else
  		printf("fcntl=%d\n",fcntl(ComPort,F_SETFL,0));
  	//测试是否为终端设备
  	if(isatty(STDIN_FILENO)==0) {
  		printf("standard input is not a terminal device\n");
	}
  	else
  		printf("isatty success!\n");
  	//设置串口参数
 	ret = set_opt(ComPort,600,8,'N',1);
  	if(ret < 0) {
		perror("set_opt error\n");
	}

	nwrite = write(ComPort,buff,8);
	printf("nwrite=%d\n ",nwrite);
	close(ComPort);
}