Port Programming

Port Programming 

Serial Port Opening and sending and accessing data using "AT" Commands

Instructions:

This code is verified in Linux Ubuntu 16.04.3 LTS

 First check the USB Port using following given command

echo Hello > /dev/pts/1

echo xyz > /dev/pts/2

echo ..... > /dev/pts/...

and so on...  put something on the position of ... when You get the response that means port can be use

exp:

echo Welcome > /dev/pts/6    hit enter

Welcome

if you get "Welcome" that means You can use that port.     

Change the path of the port in code and compile using

gcc -o serial_port serial_port.c

and run it using 

./serial_port

serial_port.c

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>

int main(){
    int fd;
    //char path[10];
    struct termios options;

    /* ################# Open the port #################*/

    printf("Enter com_port path\n sorry not now\n");
//    scanf("%c",&path);
    fd = open("/dev/pts/1", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
   {                                              /* Could not open the port */
     fprintf(stderr, "open_port: Unable to open /dev/pts/6 - %s\n",strerror(errno));
   }else{
printf("port opened\n");
    }

    fcntl(fd, F_SETFL, 0);

    /* ################ Get the current options ###############*/

    tcgetattr(fd, &options);

    /*############## set raw input, 1 second timeout */

    options.c_cflag     |= (CLOCAL | CREAD);
    options.c_lflag     &= ~(ICANON | ECHO | ECHOE | ISIG);
    options.c_oflag     &= ~OPOST;
    options.c_cc[VMIN]  = 0;
    options.c_cc[VTIME] = 10;

    /*################### set the options ##################*/

    tcsetattr(fd, TCSANOW, &options);

char buffer[400];  /* Input buffer */
      char *bufptr;      /* Current char in buffer */
      int  nbytes;       /* Number of bytes read */
      int  tries;        /* Number of tries so far */

      for (tries = 0; tries < 1; tries ++)
      {
       /* send an AT command*/
if (write(fd, "AT+CMGL=\"ALL\"\n", strlen("AT+CMGL=\"ALL\"\n")) < 3){
printf("command sent\n");
  continue;
if(write(fd, "AT+CMGL=\"ALL\"\r", strlen("AT+CMGL=\"ALL\"\r"))=="clc")
goto loop;

}



       /*################## Read characters into our string buffer ################*/

bufptr = buffer;

nbytes = read(fd, bufptr, buffer + sizeof(buffer) - bufptr - 1);
printf("%s\n",bufptr);

    char *p;

    p = strstr(buffer, "tin");
    printf("%s",p);

p = strstr(buffer, "server");
if(p == NULL) printf("not from server\n");
  *bufptr = '\0';
loop: close(fd);
 }

close(fd);
return 0;
}

                                      Give Something to the world and it will never let you down. 

                                                                                           Onkar Dubey