#include <REGX51.H>	   	// Standard 8051 defines

// Author:	Sunrom Electronics  28-Feb-2017
// Board: Output Driver Board - Expandable  Model: 1452
// Board URL: http://www.sunrom.com/m/1452
// The program can control unlimited outputs
// Compiler: Keil C51        MCU: AT89S52

// Demo Code: Understanding the logic below you can adapt this C code 
// to any target like PIC, ARM, AVR

#define DAT 		P1_0		// Define which MCU pins are connected to board
#define CLK 		P1_1
#define STORE 	P1_2

#define NUMBER_OF_74595 2								// How many board you have connected?
unsigned char outputs[NUMBER_OF_74595];	// Set that many array variables, Each bit=relay

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// -=-=-=-=-  Delay x ms       -=-=-=-=-=-=-=
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
void delay_ms(int x)	 // delays x msec (at fosc=11.0592MHz)
{
	int y=0;
	while(x>=0)
	{
		for (y=0; y<100; y++);
		x--;
	}
}
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// -=-=-=-=-  Set Output       -=-=-=-=-=-=-=
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
void set_output()
{
	unsigned char i, j, k;
		
	CLK = 0;
	STORE = 0;

	i=NUMBER_OF_74595;
	do {		
		i--;
		k=0x80;
		for(j=0; j<8; j++)	
		{
			if(outputs[i] & k)
				DAT = 1;
			else
				DAT = 0;			
		
			k = k >> 1;
			CLK = 1;
			CLK = 0;
		}
	} while(i!=0);

	STORE = 1;
	delay_ms(10);	// hold the STORE pin high for 10ms
	STORE = 0;
}
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// -=-=-=-=-  Main Program       -=-=-=-=-=-=-=
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
void main()
{
	CLK = 0;			// Set Pins Low at power up
	STORE = 0;			// Set Pins Low at power up

	delay_ms(100);		// Power Up delay 100ms

// Array storing relay status, Each bit is one relay output
	outputs[0] = 0xF0;	// 1st Board, We want to set first four relay OFF and next four ON
	outputs[1] = 0xFF; 	// 2nd Board, Here we are setting all relays high
	set_output();		// This function shift outs the array and relay are changed accordingly

	while(1) // Loop Forever
	{
		 // User Code
	}
}