LINUX Serial Communication Source __linux

Main function

int Openport (char *dev)//Open serial port

int setport (int fd, int baud,int databits,int stopbits,int parity)//Set serial port, baud rate, data bit, stop bit, checksum

int readport (int fd,char *buf,int len,int maxwaittime)/read data, parameter is serial port, buf, length, timeout time

int writeport (int fd,char *buf,int len)//Send data

void ClearPort (int fd)//If the data does not conform to the specification, this function can be called to refresh the serial port read and write data

If there is a bug, please reply to me in time, email:41063473@qq.com.

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <sys/time.h>
int Openport (char *dev)
{
int fd = open (Dev, o_rdwr| o_noctty| O_ndelay);
if ( -1 = = FD)
{
Perror ("Can" "T Open serial Port");
return-1;
}
Else
return FD;

}

int setport (int fd, int baud,int databits,int stopbits,int parity)
{
int baudrate;
struct Termios newtio;
Switch (baud)
{
Case 300:
baudrate=b300;
Break
Case 600:
baudrate=b600;
Break
Case 1200:
baudrate=b1200;
Break
Case 2400:
baudrate=b2400;
Break
Case 4800:
baudrate=b4800;
Break
Case 9600:
baudrate=b9600;
Break
Case 19200:
baudrate=b19200;
Break
Case 38400:
baudrate=b38400;
Break
Default:
baudrate=b9600;
Break
}
Tcgetattr (Fd,&newtio);
Bzero (&newtio,sizeof (newtio));
Setting C_cflag
Newtio.c_cflag &=~CSIZE;
Switch (databits)/* Set the number of data bits * *
{
Case 7:
Newtio.c_cflag |= CS7; 7 Bit data bits
Break
Case 8:
Newtio.c_cflag |= CS8; 8 Bit data bits
Break
Default
Newtio.c_cflag |= CS8;
Break
}
switch (parity)//Set Checksum
{
Case ' n ':
Case ' N ':
Newtio.c_cflag &= ~parenb; /* Clear parity enable * *
Newtio.c_iflag &= ~INPCK; /* Enable Parity checking * *
Break
Case ' O ':
Case ' O ':
Newtio.c_cflag |= (parodd | PARENB); /* Set to the Magic Magic Test *
Newtio.c_iflag |= INPCK; /* disnable Parity checking * *
Break
Case ' E ':
Case ' E ':
Newtio.c_cflag |= Parenb; /* Enable Parity * *
Newtio.c_cflag &= ~parodd; /* Conversion to even-parity *
Newtio.c_iflag |= INPCK; /* disnable Parity checking * *
Break
Case ' S ':
Case ' s ':/*as no parity*/
Newtio.c_cflag &= ~parenb;
Newtio.c_cflag &= ~cstopb;break;
Default
Newtio.c_cflag &= ~parenb; /* Clear parity enable * *
Newtio.c_iflag &= ~INPCK; /* Enable Parity checking * *
Break
}
Switch (stopbits)/Set Stop bit
{
Case 1:
Newtio.c_cflag &= ~CSTOPB; 1
Break
Case 2:
Newtio.c_cflag |= CSTOPB; 2
Break
Default
Newtio.c_cflag &= ~CSTOPB;
Break
}
Newtio.c_cc[vtime] = 0;
Newtio.c_cc[vmin] = 0;
Newtio.c_cflag |= (clocal| Cread);
Newtio.c_oflag|=opost;
Newtio.c_iflag &=~ (ixon| Ixoff| Ixany);
Cfsetispeed (&newtio,baudrate);
Cfsetospeed (&newtio,baudrate);
Tcflush (FD, Tciflush);
if (tcsetattr (fd,tcsanow,&newtio)!= 0)
{
Perror ("Setupserial 3");
return-1;
}
return 0;
}
int readport (int fd,char *buf,int len,int maxwaittime)/read data, parameter is serial port, buf, length, timeout time
{
int No=0;int Rc;int Rcnum=len;
struct Timeval TV;
Fd_set READFD;
tv.tv_sec=maxwaittime/1000; SECOND
tv.tv_usec=maxwaittime%1000*1000; Usecond
Fd_zero (&AMP;READFD);
Fd_set (FD,&AMP;READFD);
Rc=select (FD+1,&AMP;READFD,NULL,NULL,&AMP;TV);
if (rc>0)
{
while (LEN)
{
Rc=read (fd,&buf[no],1);
if (rc>0)
no=no+1;
len=len-1;
}
if (no!=rcnum)
return-1; If the received length is not the same as the desired length, return-1
return rcnum; Receive length as expected length, return length
}
Else
{
return-1;
}
return-1;
}
int writeport (int fd,char *buf,int len)//Send data
{
Write (Fd,buf,len);
}
void ClearPort (int fd)//If the data does not conform to the specification, this function can be called to refresh the serial port read and write data
{
Tcflush (Fd,tcioflush);
}
Main ()
{
int Fd,rc,i,ret;
unsigned char rbuf[256];
unsigned char wbuf[256]= "";
for (i=0;i<256;i++)
Wbuf[i]=i;
Char *dev = "/DEV/TTYS0"; String number/DEV/TTYS0 corresponds to serial port 1
FD = Openport (dev); Open serial port
if (fd>0)
{
Ret=setport (fd,4800,8,1, ' o '); Set serial port, baud rate, data bit, stop bit, check
if (ret<0)
{
printf ("Can ' t Set serial port!/n");
Exit (0);
}
}
Else
{
printf ("Can ' t Open serial port!/n");
Exit (0);
}
while (1) {
Rc=readport (fd,rbuf,5,500); Reads 5 bytes, timeout is 500 milliseconds
if (rc>0)
{
Writeport (FD,WBUF,RC);
printf ("recv:%d/n", RC);
for (i=0;i<rc;i++)
printf ("%02x", Rbuf[i]);
printf ("n");
}
Else
printf ("recv none/n");
}
Close (FD);
}