arduino/MIDI_synth/MIDI_synth.pde

   1 /*
   2  * Simple monophonic MIDI synthesizer :-)
   3  */
   4
   5 #define MIDI_NOTE_OFF 128
   6 #define MIDI_NOTE_ON  144
   7 #define MIDI_CONTROL  176
   8 #define MIDI_PITCH_BEND 224
   9
  10 #define sndout 13
  11
  12 double base_a4=440; //set A4=440Hz
  13 double note_to_freq(double n) {
  14   if( n>=0 && n<=119 ) {
  15     return base_a4*pow(2,(n-57)/12);
  16   } else {
  17      return -1;
  18   }
  19 }
  20
  21
  22 void setup() {
  23   Serial.begin(19200);
  24   pinMode(sndout, OUTPUT);
  25 }
  26
  27 void loop() {
  28   int dela=0;
  29
  30   while(1) {
  31
  32   if(Serial.available() >= 3) {
  33     double command=0, channel=0, pitch=0;
  34     command = Serial.read();
  35     channel = Serial.read();
  36     pitch = Serial.read();
  37     if(command == MIDI_NOTE_ON && pitch > 0) dela=((1000000/2)/note_to_freq(pitch));
  38     if(command == MIDI_NOTE_OFF || pitch == 0) dela = 0;
  39
  40     Serial.println(note_to_freq(pitch), DEC);
  41   }
  42
  43   if(dela > 0) digitalWrite(sndout, HIGH); delayMicroseconds(dela);
  44   digitalWrite(sndout, LOW);  delayMicroseconds(dela);
  45
  46   }
  47
  48 }