/*
button and buzzer examples for the Orangutan/WinAVR

These routines do not use the timers or interrupts

sjames_remington at yahoo dot com

*/

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


// function prototypes
unsigned char button(unsigned char wait);
void buzzer(unsigned int frequency, unsigned int duration);

/*
button(wait);

returns a value corresponding to a button press
4 = rightmost button (next to power switch)
2 = center button
1 = leftmost

if wait is nonzero, wait until a button is pressed and debounce
otherwise, return immediately

*/

#define BTNS (7<<3)
unsigned char button(unsigned char wait)
{
	volatile unsigned char save_DDRB, btn_value;

	save_DDRB = DDRB;						//save state of DDRB for LCD display and/or motors
	DDRB |= 0;							//set PORTB all input
	PORTB &= ~BTNS;							//turn off pullups as required
	btn_value = PINB & BTNS;					//read the button pins

	if(wait==0) {
	DDRB = save_DDRB;
	return btn_value>>3;						//return immediately if wait=0
	}
	
	while( (PINB & BTNS) == 0);					//otherwise, wait until a button is pressed

	do 	{
		btn_value=(PINB & BTNS);				//read the buttons again
		_delay_ms(20);						//wait 20 ms
		}
	while (btn_value != (PINB & BTNS));				//keep reading until stable
	
	DDRB=save_DDRB;							//restore DDRB
	return btn_value>>3;						//return values in range 1-7
}

/*

buzzer(frequency, duration);

Sound a tone, this time without interrupts. CPU intensive!

call arguments:

frequency is in Hz, usable range 100-10,000 Hz
duration is in milliseconds

This routine uses _delay_loop_2() to generate timing (4 cpu cycles per loop)

For correct operation, be sure to define F_CPU in Hz!

*/

void buzzer(unsigned int frequency, unsigned int duration)
{
unsigned int wait_units, loops, i;

	DDRB |= 1;							//make PORTB.0 output
	wait_units = F_CPU/(8UL * (long int) frequency);		//half of the tone period, in delay loop units
	loops = duration*F_CPU/(8000UL*wait_units);			//number of loops to execute
	for (i=1; i<=loops; i++) {					//sound the buzzer
		PORTB |= 1;						//on
		_delay_loop_2(wait_units);				//wait 1/2 tone period
		PORTB &= ~1;						//off
		_delay_loop_2(wait_units);				//wait 1/2 tone period
		}
}

int main(void)
{
	unsigned char pressed;

	buzzer(800,1000);						//beep @ 800 Hz for 1 second
	while(1) {
		pressed=button(1);					//wait till one or more buttons pressed
	if (pressed&1) buzzer(400,200);					//play a tone
	if (pressed&2) buzzer(500,200);
	if (pressed&4) buzzer(600,1000);
	}
}