main.cpp

/** 4.5 Melodie abspielen
 */
#include "mbed.h"

// speaker sound effect demo using PWM hardware output
PwmOut speaker( MBED_CONF_IOTKIT_BUZZER );

int main()
{
    int i;
    // generate a 500Hz tone using PWM hardware output
    speaker.period(1.0/500.0); // 500hz period
    speaker =0.5; //50% duty cycle - max volume
    wait(3);
    speaker=0.0; // turn off audio
    wait(2);

    // generate a short 150Hz tone using PWM hardware output
    // something like this can be used for a button click effect for feedback
    for (i=0; i<10; i++) 
    {
        speaker.period(1.0/150.0); // 500hz period
        speaker =0.25; //25% duty cycle - mid range volume
        wait(.02);
        speaker=0.0; // turn off audio
        wait(0.5);
    }

    // sweep up in frequency by changing the PWM period
    for (i=0; i<8000; i=i+100) 
    {
        speaker.period(1.0/float(i));
        speaker=0.25;
        wait(.1);
    }
    wait(2);

    // two tone police siren effect -  two periods or two frequencies
    // increase volume - by changing the PWM duty cycle
    for (i=0; i<26; i=i+2) 
    {
        speaker.period(1.0/969.0);
        speaker = float(i)/50.0;
        wait(.5);
        speaker.period(1.0/800.0);
        wait(.5);
    }
    // decrease volume
    for (i=25; i>=0; i=i-2) 
    {
        speaker.period(1.0/969.0);
        speaker = float(i)/50.0;
        wait(.5);
        speaker.period(1.0/800.0);
        wait(.5);
    }
    speaker =0.0;
    wait(2);

}