/*  Name     : main.c
 *  Purpose  : Source code for ADC0804 Interfacing with AT89C52.
 *  Author   : Gemicates
 *  Date     : 2014-02-15
 *  Website  : www.gemicates.org
 *  Revision : None
 */
 

 //Program to check the working of ADC0804 using LED's on its output port.
#include <REGX52.H>

#define input P2  				// Input port to read the values of ADC
#define output P0  				// Output port, connected to LED's.

sbit wr= P1^1;  				// Write pin. It is used to start the conversion. 
sbit rd= P1^0;  				// Read pin. It is used to extract the data from internal register to the output pins of ADC.
sbit intr= P1^2;  				// Interrupt pin. This is used to indicate the end of conversion. It goes low when conversion is complete.

void delay(unsigned int msec )                  // The delay function provides delay in msec.
{
	int i,j ;
	for(i=0;i<msec;i++)
  for(j=0;j<1275; j++);
}

void adc()  					// Function to read the values from ADC and display on the LED's.
{
	rd=1;     
	wr=0;     
	delay(1);
	wr=1;
	while(intr==1);
	rd=0;
	output=input;
	delay(1);
	intr=1;
}

void main()
{
  input=0xff;  					// Declare port 0 as input port.       
	while(1)
	{
   adc();
  }
}