#include<DS89C4xx.h>

sbit Tsignal = P3^2;
int Data_Ready;


unsigned char xdata x[500];

void SerialTx(unsigned char a)
{
    SBUF0=a;
    while(TI_0==0);            //Wait for Transmit
    TI_0=0;
}

/***********************************LOOKUP TABLE******************************************/
unsigned char lookuptable(unsigned char t)
{
 switch(t)
  {
   case 0x00 : return '0';
   break;
   case 0x01 : return '1';
   break;
   case 0x02 : return '2';
   break;
   case 0x03 : return '3';
   break;
   case 0x04 : return '4';
   break;
   case 0x05 : return '5';
   break;
   case 0x06 : return '6';
   break;
   case 0x07 : return '7';
   break;
   case 0x08 : return '8';
   break;
   case 0x09 : return '9';
   break;
   case 0x0A : return 'A';
   break;
   case 0x0B : return 'B';
   break;
   case 0x0C : return 'C';
   break;
   case 0x0D : return 'D';
   break;
   case 0x0E : return 'E';
   break;
   case 0x0F : return 'F';
   break;
  }// end switch
}// end function


/**************************************INITIALISE SERIAL PORT***********************************/

void SPort()
{
 TMOD = 0x21;         //use Timer 1 for 2nd Serial Port
 TH1 = 0xFD;          //9600 Baud Rate
 SCON0 = 0x50;
 SCON1 = 0x50;
 //TR1 = 1;       //use 2nd serial port SCON1 register
}

/**************************************TIMER FUNCTION*********************************************/
void timer0(void)
{
 TH0 = 0xFF;                            //Set timer to count from -35 = FFDDh
 TL0 = 0xDA;                            //Read every 38us.
 TR0 = 1;
 while(TF0==0);                         //Turn on Timer0
 TF0 = 0;                               //Set Flag to 0;
 TR0 = 0;                               //Turn off Timer0
}


/***************************************DISpLAY_BYTE***************************************************/
void Display_Byte()
{
  unsigned char Data_LK;
  unsigned char MSB;
  unsigned char LSB;

  unsigned int v;
  TR1=1;
 for(v=0;v<500;v++)
 {

      Data_LK = x[v];           //Store x[i] in Data_LK
      MSB = Data_LK >> 4;                  //Shift Right Bits by 4
      MSB &= 0x0F;
      MSB = lookuptable(MSB);                      //Mask bits of MSB
      SerialTx(MSB);

         LSB = x[v];
         LSB &= 0x0F;
     LSB = lookuptable(LSB);
         SerialTx(LSB);
  }

  Data_Ready = 0;
  TR1 = 0;

}


/***************************************FALLING EDGE INTERRUPT*****************************************/
void int0()interrupt 0
{
 unsigned char p;
 unsigned int u;
 unsigned int i;
 i=0;
 u=0;
 EA=0;

   for(i=0;i<500;i++)                    //Loop for 500 bytes
   {
    for(u=0;u<8;u++)                     //Bit Shift Loop
    {

     timer0();                        //Call timer0 function
     x[i] = x[i] << 1;                   //Left Bit Shift by 1
     p = Tsignal;                        //Store Tsignal to Buffer p
     x[i] |= p;
                              //OR Masking of p with x[i]
    }//End Bitshift loop

   }//end 500 bytes for loop


    IE1 = 0;
    Data_Ready = 1;

 }//end



/*********************************************MAIN*******************************************/
void main(void)
{

 PMR = PMR | 0x03;                             // Allow Internal SRAM access
 SPort();                    //Initialise Serial Port
 IE = 0x81;                 //Enable All Interrupt
 EX0 = 1;
 IT0 = 1;
 EA = 1;
 while(1)
{
 if(Data_Ready)
 {

  Display_Byte();
 }

}


}//end main