/*
 *
 *  Created on: July 02, 2011
 *      Author: Brian Redmond
 *  This program controls an ATMEGA168 (other chips may be pin compatible)
 *  with a servo on PB1 (pin 15) and 2 green LEDs on PD0 (pin 2)
 *  The servo controls a skeleton jaw opening and closing
 *  with delays at both ends and also cyclically brightens and dims
 *  the LEDs for the eyes (ISR controlled)
 *  The x values in the for loops control the range of motion for the jaw...
 *  adjust the values as needed
 *
 */

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

#ifndef F_CPU
	#define F_CPU 1000000UL
#endif

int x; // For servo stepping
static unsigned char b=20; // Initial dim value for eyes
static uint8_t dir; // For eyes whether getting dimmer or brighter

enum { UP, DOWN };

ISR(TIMER0_COMPA_vect) // Turns off both LEDs when TCNT0 matches OCR0A
{
	PORTD=(0<<0);
}

ISR(TIMER0_OVF_vect) // Turns on both LEDs on TCNT0 overflow
{
	PORTD=(1<<0); // Turns on LEDs
	switch (dir) // Increments b (LED brightness) to 250 then decrements to 20
	{
		case UP:
			if(++b == 250)
				dir=DOWN;
			break;

		case DOWN:
			if(--b==20)
				dir=UP;
			break;
	}
	OCR0A=b;
}

int main(void)
{

	DDRB=0xFF; // PORT B as output
	DDRD=0xFF; // PORT D as output

	OCR1A=1400; // Starting position for jaw ( half open)
	OCR0A=20; // Starting value for eyes (dim)
	PORTD |=(1<<0); // Turn on eyes

	ICR1=19999; // Top value for 50Hz PWM for servo control
	TCCR1A=((0<<COM1A0) | (1<<COM1A1) | (1<<WGM11)); // 16 bit timer 1 in fast PWM mode, clear OC1A on compare match
	TCCR1B=((1<<WGM12) | (1<<WGM13) | (1<<CS10)); // No prescale

	TIMSK0 |= ((1<<OCIE0A) | (1<<TOIE0)); // Use compare and overflow interrupts
	TCCR0B = ((1<<CS00) | (1<<CS01)); // Prescaler 64
	TCNT0=0; // Reset counter
	sei(); // Enable interrupts

	while(1)
	{
		_delay_ms(2000);
		for(x=1100;x<=1900;x+=100) // Slow movement of jaw from open to closed with 2 second delay at fully opened
		{
			OCR1A=x;
			_delay_ms(100); // Slows down servo movement
		}

		_delay_ms(3000);
		for(x=1800;x>=1100;x-=100) // Slow movement of jaw from closed to open with 3 second delay at fully closed
		{
			OCR1A=x;
			_delay_ms(100);
		}
	}
}