Analog To Midi with MKR 1000

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1/*
2
3  Analog to Midi Converter for Arduino MKR1000
4
5  Demonstrates how to sample an input signal and get back its corresponding MIDI note
6
7  This example code is in the public domain
8
9  https://www.arduino.cc/en/Tutorial/AnalogToMidi
10
11  created by Arturo Guadalupi <a.guadalupi@arduino.cc>
12
13  29 Jan 2016
14
15*/
16
17#include <AudioFrequencyMeter.h>
18#include <MIDIUSB.h>
19#include <frequencyToNote.h>
20#include <pitchToNote.h>
21
22#define DEPTH         60                      // Defines depth of the array for averaged frequencies
23#define HUMAN_RATE    50                      // Defines 50ms corresponding to 20 notes/s
24#define MAX_DURATION  1000                    // Defines the max play duration of the note
25
26AudioFrequencyMeter meter;
27
28int notesArray[DEPTH];                        // Array to store detected notes and find the "correct" note which occurred the most often
29int occurrences[DEPTH];                       // Array in which the number of occurrences for each note are stored
30
31bool marked[DEPTH];                           // Array to indicate which of the notes have been checked
32int frequencyIndex = 0;                       // Used to navigate to where the current note must be stored
33
34int previousNote;
35unsigned int startTime;                       // Used to determine when the note must stop
36unsigned int humanTime;                       // Used to determine when the next note can be sampled (using HUMAN_RATE timing)
37
38int intensity = 64;                           // The volume of the played note is fixed at 64
39
40void setup() {
41
42  // put your setup code here, to run once:
43
44  Serial.begin(115200);
45
46  pinMode(11, OUTPUT);
47
48  meter.setBandwidth(75.00, 600.00);          // Set available bandwidth between 75Hz and 600Hz
49
50  meter.begin(A0, 45000);                     // Initialize A0 at sample rate of 45kHz
51}
52
53void loop() {
54
55  float frequency = meter.getFrequency();
56
57  if (frequency > 0)
58
59  {
60
61    int noteIndex = searchForNote(frequency); // Find the index of the corresponding frequency
62
63    int note = notePitch[noteIndex];          // Use that index to find the corresponding note in the LUT
64
65    notesArray[frequencyIndex++] = note;      // Store the note and continue to next value in array
66
67    if (frequencyIndex > DEPTH)               // If all the notes have been stored
68
69    {
70
71      frequencyIndex = 0;                     // Reset the index
72
73      int i, j;
74
75      /*Reset all the occurrences and marked positions*/
76
77      for (i = 0; i < DEPTH; i++)
78
79      {
80
81        occurrences[i] = 0;
82
83        marked[i] = 0;
84
85      }
86
87      /*Count the number of occurrences*/
88
89      for (i = 0; i < DEPTH; i++)
90
91      {
92
93        for (j = 0; j < DEPTH; j++)
94
95        {
96
97          // If notes are the same and the note has not been marked yet
98
99          if ((!marked[j]) && (notesArray[j] == notesArray[i]))
100
101          {
102
103            occurrences[i]++;                 // Increment the number of occurrences
104
105            marked[j] = true;                 // Signal the note as marked
106
107          }
108
109        }
110
111      }
112
113      int numberOfdifferentFrequencies = 0;   // Used to determine how many different Frequencies have been detected
114
115      for (i = 0; i < DEPTH; i++)
116
117      {
118
119        // If the counter does not equal zero
120
121        if (occurrences[i] != 0)
122
123        {
124
125          // Store the the various detected Frequencies
126
127          notesArray[numberOfdifferentFrequencies] = notesArray[i];
128
129          // And the number of occurrences for each note
130
131          occurrences[numberOfdifferentFrequencies] = occurrences[i];
132
133          numberOfdifferentFrequencies++;      // Increment the number of detected Frequencies
134
135        }
136
137      }
138
139      /*Search for the maximum number of occurrences to discriminate the played note*/
140
141      int maxNumberOfFrequencies = occurrences[0];
142
143      int rightIndex = 0;
144
145      for (i = 0; i < numberOfdifferentFrequencies; i++);
146
147      {
148
149        // If a new maximum exist
150
151        if (occurrences[i] > maxNumberOfFrequencies)
152
153        {
154
155          // Update the value
156
157          maxNumberOfFrequencies = occurrences[i];
158
159          // Update the index
160
161          rightIndex = i;
162
163        }
164
165      }
166
167      note = notesArray[rightIndex];          // Note to be played is that with the most occurrences
168
169      // If the specified time has elapsed before the next note
170
171      if (millis() - humanTime > HUMAN_RATE)
172
173      {
174
175        humanTime = millis();                 // Update the timer
176
177        startTime = millis();                 // Update the note duration
178
179        noteOff(0, previousNote, intensity);  // Stop playing the previous note
180
181        previousNote = note;                  // Update previous note with the new one
182
183        Serial.println(note);                 // Print the note to be played
184
185        noteOn(0, note, intensity);           // Play the note!
186
187      }
188
189    }
190
191  }
192
193  if (millis() - startTime > MAX_DURATION)    // If maximum time elapsed
194
195    noteOff(0, previousNote, intensity);      // Turn the note off
196}
197
198int searchForNote(float frequency)
199{
200
201  float minimum = abs(frequency - noteFrequency[0]);
202
203  float newMinimum;
204
205  int index = 0;
206
207  /*Search for the nearest frequency that is in the vector*/
208
209  for (int i = 0; i < NUMBER_OF_NOTES - 1; i++)
210
211  {
212
213    newMinimum = abs(frequency - noteFrequency[i]);
214
215    if (newMinimum < minimum)
216
217    {
218
219      minimum = newMinimum;
220
221      index = i;
222
223    }
224
225  }
226
227  return index;
228}
229
230void noteOn(byte channel, byte pitch, byte velocity) {
231
232  midiEventPacket_t noteOn = {0x09, 0x90 | channel, pitch, velocity};
233
234  MidiUSB.sendMIDI(noteOn);
235}
236
237void noteOff(byte channel, byte pitch, byte velocity) {
238
239  midiEventPacket_t noteOff = {0x08, 0x80 | channel, pitch, velocity};
240
241  MidiUSB.sendMIDI(noteOff);
242}