File content as of revision 2:5366ce17fe55:

#include "mbed.h"
#include "uLCD_4DGL.h"

#define BAUD_9600    312
// new class to play a note on Speaker based on PwmOut class
uLCD_4DGL uLCD(p9,p10,p11);
int x1;
int y1;
class MIDISpeaker
{
public:
    MIDISpeaker(PinName pin) : _pin(pin) {
// _pin(pin) means pass pin to the Speaker Constructor
    }
// class method to play a note based on PwmOut class
    void PlayNote(unsigned char note, unsigned char velocity) {//volatile int duration) {
        int notef = int(note); //convert note to int
        int velocityf = int(velocity); //convert velocity to int
        double noteg = double(notef); //convert note to double
        double velocityg = double(velocityf); //convert velocity to double
        double f_n = double((noteg - 49)/12); //use piano frequency formula to find corresponding frequency
        double freq = (pow(2, f_n)) * 440;
        _pin.period(1.0/freq); //use frequency to set period of pwmout pin
        velocityg = ((velocityg/127.0) * 0.5); //calculate volume of note and set to pwmout pin
        _pin = velocityg;
        x1 = ((freq/4000)*115) + 5; //calcuate starting position for frequency spectrum [0,4000 Hz]
        y1 = 110 - ((_pin/0.5)*105); // calculate magnitude of spectrum based on velocity
        uLCD.locate(0,13);
        uLCD.printf("\nkey: %d, freq: %4.0f, volume: %.2f\n", note, freq, velocityg);
        uLCD.textbackground_color(BLUE);
        uLCD.filled_rectangle(x1, y1, x1+2, 109, BLACK);
    }
    void StopNote() {
        _pin = 0.0;
        //uLCD.filled_rectangle(x1, y1, x1+2, 109, BLUE); //code to clear rectangle from lcd
    }
    
private:
// sets up specified pin for PWM using PwmOut class 
    PwmOut _pin;
};
 
// Speaker test program - earlier euro police style siren now using new class method
//