Colony

/*

        buzzer.c - Contains the functions necessary for running the buzzer

        author: Robotics Club, Colony Project

        much taken from FWR's firefly library (author: Tom Lauwers)

*/

#include <avr/io.h>

#include "buzzer.h"

#include "time.h"

/*

initializes buffer

this function must be called before the buzzer can be used

*/

void buzzer_init( void )

{

        // Set pin D7 to output - D7 is buzzer pin

        DDRB |= 0x80;

        // Set to Fast PWM mode, toggle the OC0A pin (D6) on output compare

        // matches, and select a clock prescalar of 64 for the counter.

        // Counter FREQ = 8000000/64 = 125000

        //01011000

        TCCR2 = 0x1B;

        OCR2=100;

}

// Set the buzzer value - takes a value from 0-255

// Higher values are lower frequency.  Take a look at 

// the buzzer frequency table to see how a given value

// correlates to a frequency.

void buzzer_set_val(unsigned int buzz_value)

{ 

        OCR2 = buzz_value;

}

// Set the buzzer frequency - takes any value and tries to find the nearest buzzer frequency

void buzzer_set_freq(unsigned int buzz_freq)

{

        int buzz_value;

        buzz_value = 62500/buzz_freq - 1;

        if(buzz_value > 255)

                buzz_value = 255;

        else if(buzz_value < 0)

                buzz_value = 0;

        buzzer_set_val(buzz_value);

}

// Chirps the buzzer for a number of milliseconds

void buzzer_chirp(unsigned int ms, unsigned int buzz_freq) 

{        

        buzzer_set_freq(buzz_freq);

        delay_ms(ms);

        buzzer_off();

}

// Disables timer0 clock counting, turning off the buzzer

void buzzer_off() 

{

        // Disable clock, to halt counter

        TCCR2 &= 0xF8;

        // Set buzzer pin low in case it's high

        PORTB &= 0x7F;

}