Greenhouse monitoring and controlling system

//Header file
 #include <p18F4520.h>
 #include <delays.h>
 #include <adc.h>
 #include <system4520.h>
 #include <stdio.h> 
 #include <LCD.h>

#define		CHANNEL0	0b10000001	// AN0(ra0)
#define		fan		PORTBbits.RB4

void read_adc(void);
unsigned short read_temp(void);

unsigned short result;
unsigned short temp,tempA;

void main(void)
{
	ADRESH=0;					//clear A/D result
	ADRESL=0;					//clear A/D result

ADCON0=CHANNEL0;
ADCON1=0b11000101;			// A/D result right justified, configure RA2 and RA5 as digital I/O
ADCON2 = 0b00000100;            // Result Left justified, Manual acquisition time, Fosc/4
ADCON0bits.ADON = 1;

	TRISA=0b11011011;			//configure PORTA I/O direction
	TRISB=0b00000000;			//configure PORTB as output
	TRISC=0b00000000;			//configure PORTC as output

//PR2 = 0b01111100 ; 
//T2CON = 0b00000101 ; 
//CCP1CON = 0b00001100 ; 
//CCP2CON = 0b00111100 ; 
//CCPR1L=0; 
//CCPR2L=1; 

	PORTA=0;
	PORTB=0;

	while(1)					
	{
		LCD_init();
		cursor_set(0,0);
		PutS("Temp=    C     ");

		while(1)						//infinity loop
		{
		ADCON0=CHANNEL0;				//CHANNEL1=0b10001001
		cursor_set(0,6);			
		read_adc();
		temp=((read_temp()/255.0)*500);
		getchar(0b11011111);
		getchar('C');
		
		tempA=temp;	
			if(tempA>400)						
				{												
					fan=1;					
				}	
			else if(tempA<400) 				
				{													
					fan=0;					
				}	
		Delay10KTCYx(200);	
		}	
	}		
}
							
void read_adc(void)
{
	unsigned short i;
	unsigned long result_temp=0;
	for(i=2000;i>0;i-=1)			//looping 2000 times for getting average value 
	{
		ADCON0bits.GO = 1;					
		while(ADCON0bits.DONE);			
		result=ADRESH;
		result=result<<8;			//shift to left for 8 bit
		result=result|ADRESL;		//10 bit result from ADC
		result_temp+=result;		
	}
	result = result_temp/2000;		//getting average value
}

unsigned short read_temp(void)
{
	unsigned short temp;
	temp=result;
	return temp;
}