ช่วยอธิบายโค้ด ภาษา c ควบคุม AVR mega 8 ว่าแต่ละส่วนทำหน้าที่อะไร

/*
 * AVRGCC9.c
 *
 * Created: 29/10/2555 22:51:18
 *  Author: KAKALOS
 */ 

#include <avr/io.h>
#define F_CPU 8000000UL
#include <util/delay.h>
#include <inttypes.h>
#include <stdint.h>                     // needed for uint8_t
#include <avr/interrupt.h>
#include "lcd.c"
#include "usart.c"

#define FOSC 8000000// Clock Speed
#define BAUD 9600
#define MYUBRR FOSC/16/BAUD-1

uint8_t byteReceived;
uint8_t byteCount = 0;
uint8_t i=0,j,k,p;

uint8_t rfidTag[15] = {0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff} ;
uint8_t data1[15];
uint8_t data2[15];
int main(void)

{    
    Data1();
	Data2();
    PortInt();
	USART_Init(51);
	sei();
	lcd_init();
	lcd_clr1();
    
	while(1)
	
	{   
		    
			seedata();
			lock1();
			lock2();
			unlock1();
			unlock2();
	}   

}
ISR(USART_RXC_vect){
	
	byteReceived = UDR;								
	rfidTag[byteCount] = byteReceived;	
	byteCount++;	
								
if (rfidTag[11]==data1[11]&& rfidTag[12]==data1[12] && byteCount==16 || rfidTag[11]==data2[11]&& rfidTag[12]==data2[12] &&byteCount==16) 
{
	i=i^1;   
}

    if (byteCount==16)
    {
    byteCount=0;	
	}	
}	
void Data1()	
{
	 data1[1] = '5';
	 data1[2] =	'4';	
	 data1[3] = '0';
	 data1[4] =	'0';	
	 data1[5] = '5';
	 data1[6] =	'B';	
	 data1[7] = '6';
	 data1[8] =	'7';	
	 data1[9] = '2';
	 data1[10] ='2';	
	 data1[11] ='4';
	 data1[12] ='A';	
}	 
void clrdata2()	{
	 data2[1] = '0';
	 data2[2] =	'0';	
	 data2[3] = '0';
	 data2[4] =	'0';	
	 data2[5] = '0';
	 data2[6] =	'0';	
	 data2[7] = '0';
	 data2[8] =	'0';	
	 data2[9] = '0';
	 data2[10] ='0';	
	 data2[11] ='0';
	 data2[12] ='0';
} 	
void Data2()
{
	 data2[1] = '5';
	 data2[2] =	'4';	
	 data2[3] = '0';
	 data2[4] =	'0';	
	 data2[5] = '5';
	 data2[6] =	'C';	
	 data2[7] = '1';
	 data2[8] =	'A';	
	 data2[9] = '7';
	 data2[10] ='A';	
	 data2[11] ='6';
	 data2[12] ='8';
}
void clrdata1()	{	 
	 
	 data1[1] = '0';
	 data1[2] =	'0';	
	 data1[3] = '0';
	 data1[4] =	'0';	
	 data1[5] = '0';
	 data1[6] =	'0';	
	 data1[7] = '0';
	 data1[8] =	'0';	
	 data1[9] = '0';
	 data1[10] ='0';	
	 data1[11] ='0';
	 data1[12] ='0';	
} 
void PortInt()
{
	DDRC   |= _BV(PC0);
	DDRC   |= _BV(PC1);
    DDRC   |= _BV(PC2);
	DDRC   |= _BV(PC3);
	DDRC   &= ~_BV(PC4);
	PORTC  |= _BV(PC4);
	DDRD   &= ~_BV(PD5);
	PORTC  |= _BV(PC5);
}
void seedata()
{
		     lcd_command(0xc0);
		     lcd_putc('I');
			 lcd_command(0xc1);
		     lcd_putc('D');
			 lcd_command(0xc2);
		     lcd_putc('=');
			 lcd_command(0xc3);
			 lcd_putc(rfidTag[1]);
			 lcd_command(0xc4);
			 lcd_putc(rfidTag[2]);
			 lcd_command(0xc5);
			 lcd_putc(rfidTag[3]);
			 lcd_command(0xc6);
			 lcd_putc(rfidTag[4]);
			  lcd_command(0xc7);
			 lcd_putc(rfidTag[5]);
			  lcd_command(0xc8);
			 lcd_putc(rfidTag[6]);
			  lcd_command(0xc9);
			 lcd_putc(rfidTag[7]);
			 lcd_command(0xca);
			 lcd_putc(rfidTag[8]);
			 lcd_command(0xcb);
			 lcd_putc(rfidTag[9]);
			 lcd_command(0xcc);
			 lcd_putc(rfidTag[10]);
			 lcd_command(0xcd);
			 lcd_putc(rfidTag[11]);
			 lcd_command(0xce);
			 lcd_putc(rfidTag[12]);
			  lcd_command(0xcf);
			 lcd_putn(i);
}		

void unlock1()
{    

		if (      data1[1] == rfidTag[1] && data1[2] == rfidTag[2] && data1[3] == rfidTag[3] && data1[4] ==rfidTag[4]&&
				  data1[5] == rfidTag[5] && data1[6] == rfidTag[6] && data1[7] == rfidTag[7] && data1[8] == rfidTag[8]&&
				  data1[9] == rfidTag[9] && data1[10] == rfidTag[10] && data1[11] == rfidTag[11] && data1[12] == rfidTag[12]&& i == 0)
				{
					
					lcd_clr1();
					lcd_command(0x85);
		            lcd_putc('U');
			        lcd_command(0x86);
		            lcd_putc('N');
			        lcd_command(0x87);
		            lcd_putc('L');
					lcd_command(0x88);
		            lcd_putc('O');
			        lcd_command(0x89);
		            lcd_putc('C');
			        lcd_command(0x8a);
		            lcd_putc('K');
					lcd_command(0x8b);
		            lcd_putc('!');
	       
					PORTC |= _BV(PC0);
					PORTC  &= ~_BV(PC1);

					PORTC  &= ~_BV(PC3);
					
				if((PINC & _BV(PC4)) == 0)
					{
						PORTC  &= ~_BV(PC2);
						Data2();
						Data1();
					}	
					else
					{
						PORTC |= _BV(PC2);
					}
				}
			
								
}
void unlock2()
{					
	if (  data2[1] == rfidTag[1] && data2[2] == rfidTag[2] && data2[3] == rfidTag[3] && data2[4] ==rfidTag[4]&&
		 data2[5] == rfidTag[5] && data2[6] == rfidTag[6] && data2[7] == rfidTag[7] && data2[8] == rfidTag[8]&&
		 data2[9] == rfidTag[9] && data2[10] == rfidTag[10] && data2[11] == rfidTag[11] && data2[12] == rfidTag[12] && i == 0)		  
		{
					lcd_clr1();
					lcd_command(0x85);
		            lcd_putc('U');
			        lcd_command(0x86);
		            lcd_putc('N');
			        lcd_command(0x87);
		            lcd_putc('L');
					lcd_command(0x88);
		            lcd_putc('O');
			        lcd_command(0x89);
		            lcd_putc('C');
			        lcd_command(0x8a);
		            lcd_putc('K');
					lcd_command(0x8b);
		            lcd_putc('!');
	
					PORTC |= _BV(PC0);
					PORTC  &= ~_BV(PC1);

					PORTC  &= ~_BV(PC3);
					
				if((PINC & _BV(PC4)) == 0)
					{
						PORTC  &= ~_BV(PC2);
						Data2();
						Data1();
					}
					else
					{
						PORTC |= _BV(PC2);
					}							
				 
		}		
							
			
			
		}
		
								
void lock1()
{
		if (
				    data1[1] == rfidTag[1] && data1[2] == rfidTag[2] && data1[3] == rfidTag[3] && data1[4] ==rfidTag[4]&&
				    data1[5] == rfidTag[5] && data1[6] == rfidTag[6] && data1[7] == rfidTag[7] && data1[8] == rfidTag[8]&&
				    data1[9] == rfidTag[9] && data1[10] == rfidTag[10] && data1[11] == rfidTag[11] && data1[12] == rfidTag[12]&& i == 1 )
		{
					
					lcd_clr1();
					lcd_command(0x86);
		            lcd_putc('L');
			        lcd_command(0x87);
		            lcd_putc('O');
					lcd_command(0x88);
		            lcd_putc('C');
			        lcd_command(0x89);
		            lcd_putc('K');
					lcd_command(0x8a);
		            lcd_putc('!');
					PORTC |= _BV(PC1);
					PORTC  &= ~_BV(PC0);

					PORTC  &= ~_BV(PC2);
					if((PINC & _BV(PC5)) == 0)
					{
						PORTC  &= ~_BV(PC3);
					   
					}
					else
					{
						clrdata2();
						Data1();
						PORTC |= _BV(PC3);
						
					}						
		}
	
}

void lock2()
{	      
	if( data2[1] == rfidTag[1] && data2[2] == rfidTag[2] && data2[3] == rfidTag[3] && data2[4] ==rfidTag[4]&&
		data2[5] == rfidTag[5] && data2[6] == rfidTag[6] && data2[7] == rfidTag[7] && data2[8] == rfidTag[8]&&
		data2[9] == rfidTag[9] && data2[10] == rfidTag[10] && data2[11] == rfidTag[11] && data2[12] == rfidTag[12] && i== 1)
		{   
				
					lcd_clr1();
					lcd_command(0x86);
		            lcd_putc('L');
			        lcd_command(0x87);
		            lcd_putc('O');
					lcd_command(0x88);
		            lcd_putc('C');
			        lcd_command(0x89);
		            lcd_putc('K');
					lcd_command(0x8a);
		            lcd_putc('!');
					PORTC |= _BV(PC1);
					PORTC  &= ~_BV(PC0);

					PORTC  &= ~_BV(PC2);
					if((PINC & _BV(PC5)) == 0)
					{
						PORTC  &= ~_BV(PC3);
					    
					}
					else
					{
						clrdata1();
						Data2();
						PORTC |= _BV(PC3);
					}						

		  }	 
		  	}