linux下串口编程

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <stdio.h>
#include <sys/time.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <linux/serial.h>
#include <asm/ioctls.h>
#include <sys/io.h>
#include <time.h>

static int speed_sel[] ={B115200, B57600, B38400, B19200, B9600};
static int name_sel[] = {115200, 57600, 38400,  19200, 9600};

int open_port(char *SerialPort)
{
int fd;

fd = open(SerialPort, O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
{
printf("open_port:Unable to open %s \n", SerialPort);
}
else
fcntl(fd, F_SETFL, 0);

return (fd);
}

int close_port(int fd)
{
int rtn;

rtn = close(fd);
return (rtn);
}

void speed_set(int fd, int speed)
{
int i, status, tempspeed;
struct termios opt;
struct serial_struct p;
speed_t lngspeed;

if(fd <= 0)
return ;

tcgetattr(fd, &opt);
tempspeed = speed;
if(speed == 28800)
tempspeed = 38400;
for(i = 0; i < sizeof(speed_sel) / sizeof(int); i++)
{
if(tempspeed == name_sel[i])
{
tcflush(fd, TCIOFLUSH);
cfsetispeed(&opt, speed_sel[i]);
cfsetospeed(&opt, speed_sel[i]);

status = tcsetattr(fd, TCSANOW, &opt);
if(status != 0)
{
return ;
}
tcflush(fd, TCIOFLUSH);
}
}
lngspeed = cfgetispeed(&opt);
if(speed == 28800)
{
ioctl(fd, TIOCGSERIAL, &p);
p.flags = ASYNC_SPD_CUST;
p.custom_divisor = 4;
ioctl(fd, TIOCSSERIAL, &p);
}
lngspeed = cfgetispeed(&opt);
}

int parity_set(int fd, int databits, int stopbits, int parity)
{
struct termios opt;

if(fd <= 0)
return 1;

tcgetattr(fd, &opt);

opt.c_cflag &= ~CSIZE;
switch(databits)
{
case 7:
opt.c_cflag |= CS7;
break;
case 8:
opt.c_cflag |= CS8;
break;
}
switch(parity)
{
case 'n':
case 'N':
opt.c_cflag &= ~PARENB;
opt.c_iflag &= ~INPCK;
break;
case 'o':
case 'O':
opt.c_cflag |= (PARODD | PARENB);
opt.c_iflag |= INPCK;
break;
case 'e':
case 'E':
opt.c_cflag |= PARENB;
opt.c_cflag &= ~PARODD;
opt.c_iflag |= INPCK;
break;
case 'S':
case 's':
opt.c_cflag &= ~PARENB;
opt.c_cflag &= ~CSTOPB;
break;
}
switch(stopbits)
{
case 1:
opt.c_cflag &= ~CSTOPB;
break;
case 2:
opt.c_cflag |= CSTOPB;
}
if(parity != 'n')
opt.c_iflag |= INPCK;
opt.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
opt.c_oflag &= ~OPOST;

opt.c_iflag &= ~(IXON | IXOFF | IXANY | ICRNL);
tcflush(fd, TCIFLUSH);
opt.c_cc[VTIME] = 5;
opt.c_cc[VMIN] = 0;
tcsetattr(fd, TCSANOW, &opt);
return(1);
}

unsigned char writecom(int fd, unsigned char *pdata, long lnglen)
{
long lngwritelen;
FILE *intFile;
char chinfo[300];
long i;

if(fd <= 0)
return 0;
tcflush(fd, TCIOFLUSH);

lngwritelen = write(fd, pdata, lnglen);
if(lngwritelen == -1)
return 0;
if(lngwritelen != lnglen)
return 0;
return 0xff;
}

unsigned char readcom(int fd, unsigned char *pdata, long lnglen)
{
long lngwritelen;

if(fd <= 0)
return 0;

lngwritelen = read(fd, pdata, lnglen);
if(lngwritelen == -1)
return 0;
if(lngwritelen != lnglen)
return 0;
return 0xff;
}

int main()
{
char* SerialPort = "/dev/ttymxc2";

int csc_comm = open_port(SerialPort);

speed_set(csc_comm, 115200);
parity_set(csc_comm, 8, 1, 'n');

writecom(csc_comm,"seulww", 6);

getchar();

char str[20] = {0};
readcom(csc_comm,str,15);
printf("%s\n",str);

close_port(csc_comm);

return (csc_comm);
}