Diff: Tone.cpp

Revision:

0:836cdf67dbdb

Child:

1:f17240b3e85e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Tone.cpp	Wed Mar 08 17:15:42 2017 +0000
@@ -0,0 +1,109 @@
+#include "Tone.h"
+
+Tone::Tone(PinName dacPin)
+{
+    dac = new AnalogOut(dacPin);
+    ticker = new Ticker;
+    timeout = new Timeout;
+    note_timeout = new Timeout;
+}
+
+Tone::~Tone()
+{
+    delete dac;
+    delete[] _sample_array;
+    delete ticker;
+    delete timeout;
+    delete note_timeout;
+}
+
+void Tone::init()
+{
+    _n = 16;
+    _sample_array = new float[_n];
+
+    // create sample array for one period between 0.0 and 1.0
+    for (int i = 0; i < _n ; i++) {
+        _sample_array[i] = 0.5f + 0.5f*sin(i*2*PI/_n);
+        //printf("y[%i] = %f\n",i,_sample_array[i]);
+    }
+
+}
+
+void Tone::play(float frequency,float duration)
+{
+    // calculate time step between samples
+    float dt = 1.0/(frequency*_n);
+    // start from beginning of LUT
+    _sample = 0;
+    
+    // setup ticker and timeout to stop ticker
+    
+    // the ticker repeats every dt to plat each sample in turn
+    ticker->attach(callback(this, &Tone::ticker_isr), dt);
+    // the timeout stops the ticker after the required duration
+    timeout->attach(callback(this, &Tone::timeout_isr), duration );
+}
+
+void Tone::play_melody(int length,const int *notes,const int *durations,float bpm,bool repeat)
+{
+    // copy arguments to member variables
+    _bpm = bpm;
+    _notes = notes;  // pointer for array
+    _durations = durations;  // pointer for array
+    _melody_length = length; 
+    _repeat = repeat;  
+    
+    _note = 0;  // start from first note
+
+    play_next_note(); // play the next note in the melody
+}
+
+
+void Tone::play_next_note()
+{
+    // _note is the note index to play
+    
+    // calculate the duration and frequency of the note
+    float duration = 60.0/(_bpm*_durations[_note]);
+    float frequency = float(_notes[_note]);
+    //printf("[%i] f = %f d = %f\n",_note,frequency,duration);
+    
+    // check if the note is not a space and if not then play the note
+    if (frequency > 0) {
+        play(frequency,duration);  
+    }
+    
+    // the timeout goes to the next note in the melody
+    // double the duration to leave a bit of a gap in between notes to be better
+    // able to distinguish them
+    note_timeout->attach(callback(this, &Tone::note_timeout_isr), duration*2.0 );
+}
+
+// called when the next note needs playing
+void Tone::note_timeout_isr()
+{
+    _note++; // go onto next note
+    
+    // if in repeat mode then reset the note counter when get to end of melody
+    if (_repeat && _note == _melody_length) {
+        _note=0;    
+    }
+
+    // check if note is within the melody
+    if (_note < _melody_length) {
+        play_next_note();
+    }
+}
+
+void Tone::ticker_isr()
+{
+    dac->write(_sample_array[_sample%_n]);  // use modulo to get index to play
+    _sample++;  // increment the sample ready for next time
+}
+
+void Tone::timeout_isr()
+{
+    // stops the ticker to end the note
+    ticker->detach();
+}
\ No newline at end of file