How to establish communication between mobile phone and PC

Introduction

The article provides a step by step tutorial about the method to connect your mobile phone to your PC using serial communication. It describes the methods to execute phone specific commands via your PC.

PC and mobile phone communication can be established by three ways:

1. serial port (requires a data cable).
2. infra red port (requires infrared port on your mobile and PC).
3. Bluetooth (requires Bluetooth wireless connector).

(Note: I have just worked on serial port and infrared.)

Explanation

Initialize and open port:

/* portNm =COM1,COM2 etc which ever COM port your phone is connected */

bool OpenPort( char *portNm )  
{    
if( portNm != NULL ) // check to if port exists
    {
/* hComm is handle that makes a buffer file pointin to your
   COM port for read and write of port data */

    hComm = CreateFile( portNm,GENERIC_READ | GENERIC_WRITE, 
                        0, 
                        0, 
                        OPEN_EXISTING,
                        NULL,
                        0);

    if (hComm == INVALID_HANDLE_VALUE)
        {
        //error occured alert user about error            
        return false;
        }
    else
            // port opened successfully alert user
       return true;
    }

else
    {
      // specified port missing alert user
          return false;
    }

}

Write To Port:

BOOL WriteABuffer(char * lpBuf, DWORD dwToWrite)
{
   OVERLAPPED osWrite = {0};
   DWORD dwWritten;
   BOOL fRes;

   // Issue write.
   if (!WriteFile(hComm, lpBuf, dwToWrite, &dwWritten, NULL)) 
   {
      if (GetLastError() != ERROR_IO_PENDING) 
      {  // WriteFile failed, but it isn't delayed. Report error and abort.
      
          fRes = FALSE;
        }
      else
      {
         // Write is pending.

         if (!GetOverlappedResult(hComm, &osWrite, &dwWritten, TRUE))
         {     
             fRes = FALSE;}
         else
         {  // Write operation completed successfully.

             fRes = TRUE;}
      }
   }
   else
      // WriteFile completed immediately.

      fRes = TRUE;
  
   return fRes;
}

Read Port:

void ReadPort()

{
    DWORD dwRead;        
    char  chRead[250];  

// remember to adjust 250 according to the total data read
       
         char *count = NULL;
     
/* flush the old values and fill with some arbitary symbol 
   thats most unlikely to appear in your data to know
   the end point after reading */

    memset(chRead,'\x91',250);  

    Sleep( 5L);

    ReadFile(hComm, chRead, 250, &dwRead, NULL); 

/* now chRead contains data . you can manipulate
   it accoring to your needs now. */

}

Special setting:

After you call OpenPort, you must assign the DCB and connection timeout to the port. DCB is used to adjust communication settings of the port. You must set your port according to your needs depending upon your communication requirement.

Connection timeouts are used to assign the time for which port must forcibly stop reading data from your mobile phone to prevent abnormality in case of very long data.

if(OpenPort("COM4"))  // opens COM4 port
{
  DCB dcb
 
        dcb.fOutxCtsFlow = false;    // Disable CTS monitoring
        dcb.fOutxDsrFlow = false;    // Disable DSR monitoring
    dcb.fDtrControl = DTR_CONTROL_DISABLE;    // Disable DTR monitoring
    dcb.fOutX = false;        // Disable XON/XOFF for transmission
    dcb.fInX = false;        // Disable XON/XOFF for receiving
    dcb.fRtsControl = RTS_CONTROL_DISABLE;    // Disable RTS (Ready To Send)
    
    

   COMMTIMEOUTS timeouts;

    timeouts.ReadIntervalTimeout = 20; 
    timeouts.ReadTotalTimeoutMultiplier = 10;
    timeouts.ReadTotalTimeoutConstant = 100;
    timeouts.WriteTotalTimeoutMultiplier = 10;
    timeouts.WriteTotalTimeoutConstant = 100;

    if (!SetCommTimeouts(hComm, &timeouts))
    {
      // error with time outs .alert user and exit
    }

}

The above piece of code can be used to establish effective communication between a PC and a mobile phone.

You can issue phone specific commands to the phone interpreter which will do the processing and will return data on same port after processing. Hayes AT commands can be used with most of the phones (these are phone specific, so please check for the compatibility of these commands with your phone ). Nokia AT command set is available at Nokia official website.

AT commands can be used to perform various functions like sending/receiving SMS to your PC connected to mobile phone, synchronizing the mobile phone book, changing phone settings, and lots more.

Hope the article proves to be useful, and for any other query, you can always contact me at nitzbajaj@yahoo.com.