serial.c

本人写的linux下云台控制程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>

struct tcspeed{
	unsigned long baud;
	speed_t code;
};
static struct tcspeed tcspeeds[] = {
        {50, B50},
        {75, B75},
        {110, B110},
        {134, B134},
        {150, B150},
        {200, B200},
        {300, B300},
        {600, B600},
        {1200, B1200},
        {1800, B1800},
        {2400, B2400},
        {4800, B4800},
        {9600, B9600},
        {19200, B19200},
        {38400, B38400},
        {57600, B57600},
        {115200, B115200},
        {230400, B230400},
        {460800, B460800},
        {921600, B921600},
        {0, B0},
//        {0, 0}
};
    
int initial_serial(char* ttyS,int baudrate,int databits,char parity,int stopbits)
{
	//default value:
	// ttyS = /dev/ttyS0; 
	//baudrate = 9600; databits = 8; parity = 0; stopbits = 1;
	
	int fd,status,i,speed;
	struct termios Opt;
	
	//1.Open Serial Port
	if(ttyS == NULL)
	{
		fprintf(stderr,"error: no device!\n");
		return -1;
	}
	if(strncmp(ttyS,"/dev/ttyS",9))
	{
		fprintf(stderr,"error: Invalid device!\n");
		return -1;
	}
	fd = open(ttyS,O_WRONLY | O_NDELAY | O_NOCTTY);
	if(fd == -1)
	{
		fprintf(stderr,"Can`t Open Serial Port\n");
		return -1;
	}
//	printf("Open Serial Port Successfully\n");	
	
	//2. Set Speed	
	for ( i= 0;  i < sizeof(tcspeeds) / sizeof(struct tcspeed);  i++)
	{
		if  (speed == tcspeeds[i].baud)
		{
			tcgetattr(fd,&Opt);
			tcflush(fd, TCIOFLUSH);
			cfsetispeed(&Opt,tcspeeds[i].code);
			cfsetospeed(&Opt,tcspeeds[i].code);
			status = tcsetattr(fd, TCSANOW, &Opt);
			if  (status != 0)
			{
				perror("tcsetattr speed");
				return -2;
			}
//			printf("Set Speed Successfully\n");
			break;
		}
	}

	//3. Set databits,parity and stopbits
	if(tcgetattr(fd,&Opt) != 0)
	{
		perror("tcgetattr");
		return -3;
	}
	Opt.c_cflag &= ~PARENB;
	Opt.c_cflag &= ~CSTOPB;
	Opt.c_cflag &= ~CSIZE;
	Opt.c_cflag |= CS8;

	Opt.c_oflag &= ~OPOST;

	tcflush(fd,TCIFLUSH);
	if(tcsetattr(fd,TCSANOW,&Opt) != 0)
	{
		perror("tcsetattr 8N1");
		return -3;
	}
//	printf("Set 8N1 Successfully\n");

//	fprintf(stderr,"open serial seccuss!\n"); //delete by edgarliu
	
	return fd;
}

int close_serial(int fd)
{
	close(fd);
	return 0;
}