switching four devices using a PRESET

#include<reg52.h>
#define cmdport P3
#define dataport P2
#define adc_input P1

sbit rs = cmdport^2;  
sbit rw = cmdport^1;  
sbit e  = cmdport^0;
sbit wr= cmdport^4;
sbit rd= cmdport^3;
sbit intr= cmdport^5;
sbit relay1=P0^0;
sbit relay2=P0^1; 
sbit relay3=P0^2; 
sbit relay4=P0^3; 

unsigned char i,a,d1,d2,d3,d4,x1,x2,x3,x4,b,c,d,z[4];
 

unsigned char text[]= "SW1:OFF SW2:OFF ";
unsigned char text1[]= "SW3:OFF SW4:OFF ";
unsigned char text2[]= "ON ";
unsigned char text3[]= "OFF";

unsigned char i,a,b,c,d,input;

void delay(unsigned int msec)  
{
int i,j ;
for(i=0;i<msec;i++)
for(j=0;j<1275;j++);
}

void lcdcmd(unsigned char item)  
{
dataport = item;
rs= 0;
rw=0;
e=1;
delay(1);
e=0;
}

void lcddata(unsigned char item)  
{
dataport = item;
rs= 1;
rw=0;
e=1;
delay(1);
e=0;
}

void convert(unsigned int value)
{
	x1 = value / 10;
	d1 = value % 10;
	
	x2 = x1 / 10;
	d2 = x1 % 10;
	
	x3 = x2 / 10;
	d3 = x2 % 10;							   
	
	d4 = x3 % 10;

	d1=d1|0x30;
	d2=d2|0x30;
	d3=d3|0x30;
	d4=d4|0x30;
	

	lcddata(d4);
	lcddata(d3);
	lcddata(d2);
	lcddata(d1);
}



void main(void)
{

adc_input=0xff;
relay1=0;
relay2=0;
relay3=0;
relay4=0;

delay(50);

lcdcmd(0x38);  
delay(100);
lcdcmd(0x0E);  
delay(100);
lcdcmd(0x01);  
delay(100);
lcdcmd(0x06);  
delay(100);
lcdcmd(0x80);  
delay(100);

for(i=0;i<=15;i++)
{
lcddata(text[i]);
delay(1);
}

lcdcmd(0xc0);
delay(1); 

for(i=0;i<=15;i++)
{
lcddata(text1[i]);
delay(1);
}
lcdcmd(0x80);


while(1)
{		
				for(i=0;i<3;i++)
                {
                delay(1);
                rd=1;
                wr=0;
                delay(1);
                wr=1;
                while(intr==1);
                rd=0;
                lcdcmd(0x88);
                input=adc_input;
                delay(1);
                intr=1;
                z[i]=input;
                }			
				z[3]=(z[0]+z[1]+z[2])/3;
				input=z[3];
				lcdcmd(0x01);
				lcdcmd(0x80);
				convert(z[2]);
				
				if(input>20&&input<50)
				{
				  delay(100);
				 
				  if(a==0)
				  {
				  relay1=1;
				  a=1;
				  lcdcmd(0x84); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text2[i]);
				  delay(1);
                  }
				  }
				  else
				  {
				  relay1=0;
				  a=0;
				  lcdcmd(0x84);
				  delay(1); 
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text3[i]);
				  delay(1);
                  }
				  }
				  delay(200);
				 }
			     else if(input>70&&input<95)
				 {
				  delay(100);
				  if(b==0)
				  {
				  relay2=1;
				  b=1;
				  lcdcmd(0x8C); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text2[i]);
				  delay(1);
                  }
				  }
				  else
				  {
				  relay2=0;
				  b=0;
				  lcdcmd(0x8C); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text3[i]);
				  delay(1);
                  }
				  }
				  delay(200);
				 }
			     else if(input>100&&input<120)
				 {
				  delay(100);
				  if(c==0)
				  {
				  relay3=1;
				  c=1;
				  lcdcmd(0xc4); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text2[i]);
				  delay(1);
                  }
				  }
				  else
				  {
				  relay3=0;
				  c=0;
				  lcdcmd(0xc4); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text3[i]);
				  delay(1);
                  }
				  }
				  delay(200);
				 }
			     else if(input>120)
				 {
				  delay(100);
				  if(d==0)
				  {
				  relay4=1;
				  d=1;
				  lcdcmd(0xCC);
				  delay(1); 
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text2[i]);
				  delay(1);
                  }
				  }
				  else
				  {
				  relay4=0;
				  d=0;
				  lcdcmd(0xCC); 
				  delay(1);
				  for(i=0;i<=2;i++)
                  {
                  lcddata(text3[i]);
				  delay(1);
                  }
				  }
				  delay(200);
				 }	 
}

}