interfacing gsm sim300 with PIC18f4550 ( RX & TX ) probem ..

  // this code is for sending and receiving a SMS + sending back  (my code)


#include<p18f4550.h>
#include<delays.h>
#define FREQ 12000000
#define baud 9600
#define spbrg_value (((FREQ/64)/baud)-1)

#pragma config PLLDIV = 3
#pragma config CPUDIV = OSC1_PLL2
#pragma config FOSC = HS
#pragma config MCLRE = ON
#pragma config WDT = OFF, DEBUG = OFF
#pragma config LVP = OFF
#pragma config PWRT = OFF 
#pragma config PBADEN = OFF
#pragma config ICPRT = OFF
 
 //    defining LCD PORT   
 //---------------------------------
#define ldata PORTD    
#define rs PORTCbits.RC0
#define rw PORTCbits.RC1
#define en PORTCbits.RC2
#define send PORTBbits.RB1 
#define rec PORTBbits.RB2


 //Defining the LCD commands
//------------------------------------------
void lcdcmd(unsigned char value)
{
ldata = value;
rs = 0;
rw = 0;
en = 1;
Delay100TCYx( 30 );
en = 0;
}

 
//Defining the LCD display
//------------------------------------------
void lcddata(unsigned char value)
{
ldata = value;
rs = 1;
rw = 0;
en = 1;
Delay100TCYx( 30 );
en = 0;
}


// LCD initialization 
// ------------------------------

void lcd_ini()
{
lcdcmd(0x38);   //LCD matrix
Delay10KTCYx( 75 );
lcdcmd(0x0E);   //Blink curser
Delay10KTCYx( 4 );
lcdcmd(0x01);   //Clear LCD
Delay10KTCYx( 4 );
lcdcmd(0x06);     //increment curser
Delay10KTCYx( 4 );
lcdcmd(0x80); //start at firs line, first position
Delay10KTCYx( 4 );
}



// define serial communication ( receiving data from GPS)
//---------------------------------------
unsigned char rx_data(void); //receiving data function
void tx_data(unsigned char serial_data);     // Transmit data function
 
void display( unsigned char array[], int size); // to display any string on LCD
void transmit( unsigned char array2[], int size2); // to send any string to TX pin

unsigned char ch=0;
int i=0,j,k;
unsigned char welcome[]=" Welcome ";
unsigned char choice[]="Send or receive? "; 
unsigned char sending[]=" Sending .. ";
unsigned char waiting[]=" Waiting for SMS";
unsigned char sms_received[]=" SMS Received ";
unsigned char sending_back[]=" Sending Back: Hello";
unsigned char double_qoutes[]="\""; // to print "
unsigned char sms_send[]="AT+CMGS=";
unsigned char sms_format[]="AT+CMGF=1\r"; // TEXT mode
unsigned char sms_write[]="AT+CMGS=\"xxxxxxxxxx\"\r";  // 10-Digit Mobile Number
unsigned char sms[]="Hello\r";
unsigned char sms_report[]="SMS Sent...";
unsigned char sms_indication[]="AT+CNMI=1,2,0,0,0\r";
unsigned char phone_number[10];
unsigned char stringArray[46]; //to store the received sms information
unsigned char text[2]; // to store the text message
unsigned char sms_terminate=0x1A;
unsigned char enter=0x0D;
 
 

void main()
{
  
TRISD = 0;  //Set it output for the LCD
TRISCbits.RC0 = 0; //Set it output for RS
TRISCbits.RC1 = 0; //Set it output for RW
TRISCbits.RC2 = 0; //Set it output for en
TRISCbits.RC6 = 0; //TX pin set as output
TRISCbits.RC7 = 1; //RX pin set as input
TRISBbits.RB1 = 1; // To send an SMS
TRISBbits.RB2= 1; // To Receive an SMS

// serial communicatin configuration 

SPBRG=spbrg_value; //Fill SPBRG register to set the baud rate
RCSTAbits.SPEN=1; // To activate serial port (Tx and Rx pins)
RCSTAbits.CREN=1; // to enable continous receiving
TXSTA=0x24; // To enable transmition & low baud rate + 8-bits
 
   
   lcd_ini();

  Delay10KTCYx( 250);

        display( welcome, sizeof(welcome));
         Delay10KTCYx( 250);
         Delay10KTCYx( 250);
         Delay10KTCYx( 250);
       
 
           
   while(1)
   {      
      lcdcmd(0x01);
      lcdcmd(0x80);
      Delay10KTCYx( 250);
      display( choice, sizeof(choice));
        Delay10KTCYx( 250);
       

          if(send==1)
            {
             lcdcmd(0x01);
             lcdcmd(0x80);
             Delay10KTCYx( 250);
             display(sending, sizeof(sending));
             Delay10KTCYx( 250);
             transmit(sms_format, sizeof(sms_format)); // to set the mode 
             Delay10KTCYx( 250);

             transmit(sms_write, sizeof(sms_write));
             Delay10KTCYx( 250);
             transmit(sms, sizeof(sms));   
             tx_data(sms_terminate);
              lcdcmd(0x01);
             lcdcmd(0x80);
             Delay10KTCYx( 250);
             display(sms_report, sizeof(sms_report));
             Delay10KTCYx( 250);
             Delay10KTCYx( 250);
              
               }  
       
        if(rec==1)
          {
          lcdcmd(0x01);
             lcdcmd(0x80);
             Delay10KTCYx( 250);
             display(waiting, sizeof(waiting));
             transmit(sms_format, sizeof(sms_format)); // to set the mode 
             transmit(sms_indication, sizeof(sms_indication)); 
            
   
        ch = rx_data();       
        if(ch == '+')
        {
            do
            {
                ch = rx_data();
            }while(ch != '\n');

            i = 0;

            do
            {
                text[i++] = rx_data();
            }while(i < 2 );
                
        }

              lcdcmd(0x01);
             lcdcmd(0x80);
             Delay10KTCYx( 250);
             display(text, sizeof(text));
             Delay10KTCYx( 250);
             Delay10KTCYx( 250);  
    

            
          
    



        }
} //end while1


}// end main function

//------ methods ---------

unsigned char rx_data(void)
{
while(PIR1bits.RCIF==0); // Wait until RCIF gets low
return RCREG; // Store data in Reception register
}

void tx_data(unsigned char serial_data)      // Transmit data function
{
   TXREG=serial_data;
   while(PIR1bits.TXIF==0);
}
 
void display( unsigned char array[], int size)
{
    for(i=0; i<size; i++)
      {
         lcddata(array[i]);
      }
}

void transmit( unsigned char array2[], int size2)
{
    for(i=0; i<size2; i++)
     {
       tx_data(array2[i]);
     }
}