روشن و خاموش کردن رله با سوئیچ فشاری با Attiny 13

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
unsigned char relay_on_off_flag =0;
unsigned char relay_flag =0;
//---------------------------------------------------------------
void init_port(void)
{
	DDRB = 0xFE; //PIN no 0 as input
	PORTB = 0x01; //0 internally pullup
}
//----------------------------------------------------------------
void relay_on(void)
{
	PORTB =PORTB | 0x04; //function for relay on
}
void relay_off(void)
{
	PORTB =PORTB & 0xFB; //function for relay off
}
//----------------------------------------------------------------
int main()
{
	unsigned int flag=0;
	init_port();
	while(1)
	{
		if((bit_is_clear(PINB, 0 )) && (relay_on_off_flag ==0)) //If button is pressed at first time
		{
			relay_on_off_flag=1; //relay flag
			relay_flag=1; //relay on off flag
			_delay_ms(500); //delay in ms to avoid the key debounce
		}
		else if((bit_is_set(PINB, 0 )) && (relay_on_off_flag == 0)) //If button is not pressed
		{
			if(relay_flag !=1) //check relay is off or on
			{
				relay_flag=0; //relay off
				relay_on_off_flag=0;
			}
			else
			{
				relay_flag=1; // relay on
				relay_on_off_flag=1;
			}
		}
		else if((bit_is_clear(PINB, 0 )) && (relay_on_off_flag == 1)) //If button is pressed at second time
		{
			relay_on_off_flag=1; //relay flag
			relay_flag=0; //relay on off flag
			_delay_ms(500); //delay in ms to avoid the key debounce
		}
		else if((bit_is_set(PINB, 0 )) && (relay_on_off_flag == 1)) //If button is not pressed
		{
			if(relay_flag !=1) //check relay is off or on
			{
				relay_flag=0; //relay off
				relay_on_off_flag=0;
			}
			else
			{
				relay_flag=1; // relay on
				relay_on_off_flag=1;
			}
		}
		if(relay_flag==1) //check for relay on off flag
		{
			relay_on(); // if flag is 1 then relay on
		}
		else //else relay is off
		{
			relay_off();
		}
	}
}
//----------------------------------------------------------------