uart 485串口接口代码

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


const int speed_arr[] = {B230400,B115200,B57600,B38400,B19200,B9600,B4800,B2400,B1800,B1200,B600,B300};
const int name_arr[] =  { 230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1800, 1200, 600, 300};

int open_uart(const char *devname)
{
	//int fd = open(devname, O_RDWR | O_NOCTTY | O_NDELAY);
	int fd = open(devname, O_RDWR);
	if(fd < 0)
	{
		printf("uart port open failure\n");
		return -1;
	}
	return fd;
}

int set_uart_speed(int fd, int speed)
{
	int   i;
	int   status;
	struct termios   Opt;
	tcgetattr(fd, &Opt);
	for ( i= 0;  i < (int)(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 -1;
      		}
      		tcflush(fd,TCIOFLUSH);
			return 0;
    	}
  	}
	return -1;
}

////////////////////////////////////////////////////////////////////////////////
/**
*@brief   set uart databits,stopbits
*@param  fd
*@param  databits  7,8
*@param  stopbits  1,2
*@param  parity 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 -1;
	}

	options.c_cflag &= ~CSIZE;
	switch (databits)
	{
		case 7:
			options.c_cflag |= CS7;
			break;
		case 8:
			options.c_cflag |= CS8;
			break;
		default:
			fprintf(stderr,"Unsupported data size\n");
			return -1;
	}

	switch (parity)
	{
		case 'n':
		case 'N':
			options.c_cflag &= ~PARENB;   /* Clear parity enable */
			options.c_iflag &= ~INPCK;     /* Enable parity checking */
			options.c_iflag = IGNPAR;
			break;
		case 'o':
		case 'O':
			options.c_cflag |= (PARODD | PARENB);
			options.c_iflag |= INPCK;             /* Disable parity checking */
			break;
		case 'e':
		case 'E':
			options.c_cflag |= PARENB;     /* Enable parity */
			options.c_cflag &= ~PARODD;
			options.c_iflag |= INPCK;       /* Disable 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 -1;
	}

	switch (stopbits)
	{
		case 1:
			options.c_cflag &= ~CSTOPB;
			break;
		case 2:
			options.c_cflag |= CSTOPB;
			break;
		default:
			fprintf(stderr,"Unsupported stop bits\n");
			return -1;
	}
	/* Set input parity option */
	if (parity != 'n')
		options.c_iflag |= INPCK;

	tcflush(fd,TCIFLUSH);
	options.c_cc[VTIME] = 1;
	options.c_cc[VMIN] = 1;
	options.c_cflag |= HUPCL | CREAD | CLOCAL;
	options.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  /*Input*/
	options.c_oflag  &= ~OPOST;   /*Output*/
	if (tcsetattr(fd,TCSANOW,&options) != 0)
	{
		perror("SetupSerial");
		return -1;
	}
	return 0;
}

void close_uart(int fd)
{
	if(fd >=0 ){
		close(fd);
	}
}