头文件：
#ifndef _UART_H_
#define _UART_H_
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
/*
baud rate
=============
B600
B1200
B9600
B19200
B38400
B57600
B115200
B230400
B460800
B921600
B1000000
B2000000
B3000000
B4000000
*/
/**
*@brief set uart port baud rate
*@param fd[in] file descriptor of uart port
*@param baud[in] baud rate like B9600
*@return none
*/
void set_baud(int fd, int baud)
{
int status;
struct termios opt;
tcgetattr(fd, &opt);
tcflush(fd, TCIOFLUSH);
cfsetispeed(&opt, baud);
cfsetospeed(&opt, baud);
status = tcsetattr(fd, TCSANOW, &opt);
if (status != 0) {
perror("tcsetattr fd1");
return;
}
tcflush(fd,TCIOFLUSH);
}
/**
*@brief set word length, parity and stop bits
*@param fd[in] file descriptor of uart port
*@param databits[in] bits of word, valid value 5/6/7/8
*@param stopbits[in] stop bits, valid value 1 or 2
*@param parity[in] parity should be one of None,Even,Odd,Mark,Space
*/
int set_params(int fd, int databits, int stopbits, int parity)
{
struct termios options;
if ( tcgetattr( fd,&options) != 0) {
perror("tcgetattr fail");
return -1;
}
options.c_iflag = 0;
options.c_oflag = 0;
//setup data bits
options.c_cflag &= ~CSIZE;
switch (databits) {
case 5:
options.c_cflag |= CS5;
break;
case 6:
options.c_cflag |= CS6;
break;
case 7:
options.c_cflag |= CS7;
break;
case 8:
options.c_cflag |= CS8;
break;
default:
return -1;
}
//parity
switch (parity) {
case 'n':
case 'N':
options.c_cflag &= ~PARENB; // Clear parity enable/
options.c_iflag &= ~INPCK; // disable input parity checking/
break;
case 'o':
case 'O':
options.c_cflag |= (PARODD | PARENB); // odd parity checking
options.c_iflag |= INPCK; // enable parity checking
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; // Enable parity /
options.c_cflag &= ~PARODD; // even parity/
options.c_iflag |= INPCK; // enable parity checking /
break;
case 'M':
case 'm': //mark parity/
options.c_cflag |= PARENB | CMSPAR | PARODD;
options.c_iflag |= INPCK; // enable parity checking /
break;
case 'S':
case 's': //space parity/
options.c_cflag |= PARENB | CMSPAR;
options.c_cflag &= ~PARODD;
options.c_iflag |= INPCK; //enable parity checking /
break;
default:
return -1;
}
// stop bits/
switch (stopbits) {
case 1:
options.c_cflag &= ~CSTOPB;
break;
case 2:
options.c_cflag |= CSTOPB;
break;
default:
return -1;
}
// cts rts /
//if ( uartID == 1 || uartID == 2 )
// options.c_cflag |= CRTSCTS;
//else
options.c_cflag &= ~CRTSCTS;
options.c_lflag = 0;
options.c_cc[VTIME] = 10;
options.c_cc[VMIN] = 1;
// Set input parity option /
tcflush(fd,TCIFLUSH);
if (tcsetattr(fd,TCSANOW,&options) != 0) {
return -1;
}
return 0;
}
speed_t getBaudrate(int baudrate)
{
switch(baudrate)
{
case 0: return B0;
case 50: return B50;
case 75: return B75;
case 110: return B110;
case 134: return B134;
case 150: return B150;
case 200: return B200;
case 300: return B300;
case 600: return B600;
case 1200: return B1200;
case 1800: return B1800;
case 2400: return B2400;
case 4800: return B4800;
case 9600: return B9600;
case 19200: return B19200;
case 38400: return B38400;
case 57600: return B57600;
case 115200: return B115200;
case 230400: return B230400;
case 460800: return B460800;
case 500000: return B500000;
case 921600: return B921600;
case 1000000: return B1000000;
case 1152000: return B1152000;
case 1500000: return B1500000;
case 2000000: return B2000000;
case 2500000: return B2500000;
case 3000000: return B3000000;
case 3500000: return B3500000;
case 4000000: return B4000000;
default: return 1152000;
}
return 1152000;
}
int uartDevInit(int fd, int uartBaud)
{
//printf("baud=%d\n", baud);
set_baud(fd, getBaudrate(uartBaud));
// uart param /
if(set_params(fd, 8, 1, 'n'))
{
printf("Set uart parameters fail.\n");
return -1;
}
return 0;
}
#endif
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "uart.h"
int main()
{
int fd ;
int buf[20];
fd = open("/dev/ttyS4",O_RDWR);
uartDevInit(fd,115200);
while(1)
{
read(fd,buf,20);
printf("%d\n",buf[0]);
}
return 0;
}