#include <avr/io.h>
#include <avr/interrupt.h>
#define F_CPU 8000000UL //8 MHz
#include <util/delay.h>

unsigned char hybyte=0;
int result=0;
unsigned char dutydata=0;
unsigned char state=0;

void adcread();
void random_delay();
int main()
{
cli();//disable gobal interrupts
//pwm setup
DDRB |= 0b00010000; //set pin 3 as output pb4
TCCR1 = 0b00000001;
GTCCR = 0b01100000; //enable pwm
OCR1B=0; //duty cycle
//adc setup
ADMUX = 0b00001111; //set adc reference and select channel to adc4 the internal temp sensor
ADCSRA = 0b10000110; //enable adc and set presalcer to divide by 64
//watchdog
WDTCR = 0b01010010;
sei(); //enable global interrupts

while(1){
ADMUX=0b00000001;//set adc to read from photoresistor on adc1, pin 7
adcread();
if(result < 25){
state=1;
}
if(result > 40){
state=0;
dutydata=0;
}
if(state==1){
ADMUX=0b00001111;//set adc to read from channel 4, the internal temp sensor
adcread();
	while(result>255){
		if(result>=512){
		result=result-512;
		}
		if(result>=256){
		result=result-256;
		}
	}
srand(result);
dutydata=rand()%255;
random_delay(result);
}
}
return 0;


}

ISR(WDT_vect){
OCR1B =dutydata;
}


void adcread(){
ADCSRA |= (1 << ADSC);         // start ADC measurement
    while (ADCSRA & (1 << ADSC)==1){} // wait till conversion complete 
result = ADCL;
hybyte = ADCH;
	while (hybyte > 0){
		if (hybyte >=2){
		result=result + 512;
		hybyte=hybyte-2;
		}
		if (hybyte >=1){
		result=result+256;
		hybyte=hybyte-1;
		}  
	}
}


void random_delay(int count){
while(count--){
_delay_ms(1);
}
}