| 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 | } |