Arduino MIDI Send Produces No Sound

In this tutorial, you'll learn about Arduino MIDI Send Produces No Sound. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

The Problem

MIDI messages sent from Arduino are not heard on the synthesizer.

Quick Fix

Wrong

#include <MIDI.h>

MIDI_CREATE_DEFAULT_INSTANCE();

void setup() { MIDI.begin(1); }

void loop() {
  MIDI.sendNoteOn(60, 127, 1);  // No NoteOff
  delay(500);
}```

No sound. Notes are sent but never released (no NoteOff).

### Right

```cpp
#include <MIDI.h>

MIDI_CREATE_DEFAULT_INSTANCE();

void setup() {
  MIDI.begin(1);
  Serial.begin(115200);
}

void loop() {
  MIDI.sendNoteOn(60, 127, 1);
  MIDI.sendNoteOn(64, 100, 1);
  MIDI.sendNoteOn(67, 100, 1);
  delay(1000);
  MIDI.sendNoteOff(60, 0, 1);
  MIDI.sendNoteOff(64, 0, 1);
  MIDI.sendNoteOff(67, 0, 1);
  delay(500);
}```

C major chord plays for 1 second, then stops cleanly.

## Prevention

MIDI requires both NoteOn and NoteOff. NoteOn starts a note that sustains until NoteOff is received. Always match every sendNoteOn() with sendNoteOff(). Channel (third arg) must match the synthesizer. Baud rate is 31250 (library auto-sets). Use MIDI hardware: serial TX through 220-ohm resistor and 6N138 optocoupler to MIDI OUT pin 5.

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## FAQ

<details style="margin-bottom:12px;border:1px solid #e2e8f0;border-radius:10px;overflow:hidden"><summary style="cursor:pointer;padding:14px 18px;font-weight:600;font-size:1.05rem;background:#f8fafc;border-bottom:1px solid #e2e8f0;color:#1e293b">### Why is there no sound?</summary><div style="padding:14px 18px;color:#475569;line-height:1.7;background:#fff"><p>Check: channel match (1-16), MIDI cable wiring, optocoupler direction, synthesizer input channel, volume. Verify with MIDI-OX on PC.</p>
<h3 id="what-is-velocity">What is velocity?</h3><p>Velocity (0-127) = how hard the key was pressed. 127 = max, 0 = NoteOff. Some synths ignore velocity.</p>
<h3 id="do-i-need-a-midi-shield">Do I need a MIDI shield?</h3><p>For proper 5-pin DIN MIDI, yes. The shield includes optocoupler, resistors, and DIN connector. Alternatively build your own: TX -&gt; 220 Ohm -&gt; pin 5, pin 4 -&gt; 6N138 -&gt; RX.</p>
</div></details>