/***********************************************************************
*
*	Slave-Flash with Attiny24
*
* 	Description:
*	A photo-diode registers a flash and counts an internal counter
*	if the counter reaches the limit an second flash is triggered.
*
*	Ports:
*	PB3 Reset, active low, 10k to VCC, pushbutton to GND
*	PB2 Interrupt int0, active high, 1k to Pushbutton, 10k to GND Pulldown
* 	PB1	Clock	(Xtal2), UNUSED 
*	PB0	
*	PA7	
*	PA6	
*	PA5	fire
*	PA4 	statusled
*	PA3	
*	PA2	
*	PA1 
*	PA0	
*
*	power consumption: 0.5mA in normal mode, 2mA when LED lights, 8mA when firing
*
*	Date: 15.7.2011
***********************************************************************/

#ifndef F_CPU
// #warning "F_CPU not defined, is set to 1MHz"
#define F_CPU 1000000UL    
#endif

#include <inttypes.h>
#include <avr/io.h>
#include <util/delay.h>
#include <avr/sleep.h>
#include <avr/interrupt.h> 
#include "slaveflash.h"


void init(void)
{
	statusledport &= ~(1<<statusled);	
	statusledDDR |= (1<<statusled);	

	fireledport &= ~(1<<fireled);		
	fireledDDR |= (1<<fireled);		
	
	// Flashdetect-Interrupt 
	MCUCR = (1<<ISC01);					// A rising Edge at Int0 generates Interrupt
	GIMSK |= (1<<INT0);					// aktivate interupt for int0

	// reduce power consumption by switching off unneeded options
	ACSR |= (1<<ACD);						// Analog comparator disable
	ADCSRA = 0;							// ADC disable
	PRR = (1<<PRTIM0) | (1<<PRUSI) | (1<<PRADC);	// shut down timer1, USI, ADC for power reduce

	// Timer to reset the flashcounter
	TCCR1B = (1<<CS12) | (1<<CS10);			// Prescaler 1024
	TIMSK1 = (1<<TOIE1);					// Overflow interrupt enable

	flashcount = 0;						// clear all counted flashes
	flashesneeded = 0;					// initialise flashesneeded to zero
}

ISR(TIM1_OVF_vect)			// Timer 0 Overflow
{
	cli();
	TCNT1 = 63600;					// preload the timer counter for about 1s.
	if(flashesneeded == 0)				// if still learning 
	{
	flashesneeded = flashcount;			// timer kicking in after learning flashes
	}
	flashcount = 0;					// Reset the counted flashes
	statusledport &= ~(1<<statusled);		// clear the statusled
	sei();
}

ISR(INT0_vect)				// Interrupt Service routine for the int0-Pin (PB2 = interrpt)
{
	cli();
	TCNT1 = 63600;					// preload the timer counter for about 1s.
	statusledport ^= (1<<statusled);		
	flashcount++;
	if (flashesneeded > 0) if (flashcount == flashesneeded) fire();
	sei();
}



int main(void)
{
	init();						// Set all Registers and initialise
	
	_delay_ms(100);					// Wait a 'bit'

	signal(2);						// signal correct startup
	sei();						// enable interrupts
	for(;;);						// do nothing, everything important is done in the interrupt routines

return 0;
}


void signal(uint8_t counter)
{
uint8_t i;
for(i = 0; i<counter; i++)
	{
		statusledport |= (1<<statusled);
		_delay_ms(50);
		statusledport &= ~(1<<statusled);
		_delay_ms(150);
	}		
}


void fire(void) 
{
	// Release the slave-flash
	fireledport |= (1<<fireled);
	_delay_ms(250);						// enough to release the flash
	fireledport &= ~(1<<fireled);
	_delay_ms(100);						// wait a bit before going back and reactivating the interrupt
	flashcount = 0;
}