MIDI input

MidiDriver.cpp

@@ -2,19 +2,83 @@
 
 // MIDI UART Pins (GP0/GP1)
 #define PIN_MIDI_TX 0
+#define PIN_MIDI_RX 1
 
 MidiDriver midi;
 
-MidiDriver::MidiDriver() {
+MidiDriver::MidiDriver() : lastInputNote(-1), lastInputVelocity(0), _runningStatus(0), _byteIndex(0), _data1(0), _data2(0) {
 }
 
 void MidiDriver::begin() {
     mutex_init(&_mutex);
     Serial1.setTX(PIN_MIDI_TX);
+    Serial1.setRX(PIN_MIDI_RX);
     Serial1.begin(31250);
     Serial.println(F("MIDI Serial initialized on GP0/GP1"));
 }
 
+void MidiDriver::update() {
+    while (Serial1.available()) {
+        uint8_t b = Serial1.read();
+        Serial1.write(b); // Soft THRU: Merge input with output
+
+        // Realtime messages don't affect running status
+        if (b >= 0xF8) continue;
+
+        if (b >= 0x80) {
+            _runningStatus = b;
+            _byteIndex = 0;
+        } else if (_runningStatus) {
+            if (_byteIndex == 0) {
+                _data1 = b;
+                _byteIndex++;
+                
+                // Handle 2-byte messages (Program Change 0xC0, Channel Pressure 0xD0)
+                uint8_t type = _runningStatus & 0xF0;
+                if (type == 0xC0 || type == 0xD0) {
+                     _byteIndex = 0; // Message complete
+                }
+            } else if (_byteIndex == 1) {
+                _data2 = b;
+                _byteIndex = 0; // Message complete
+                
+                uint8_t channel = (_runningStatus & 0x0F) + 1;
+                uint8_t type = _runningStatus & 0xF0;
+                if (type == 0x90) {
+                    if (_data2 > 0) {
+                        // Serial.print(F("Note On CH"));
+                        // Serial.print(channel);
+                        // Serial.print(F(": "));
+                        // Serial.print(_data1);
+                        // Serial.print(F(" Vel: "));
+                        // Serial.println(_data2);
+                        lastInputNote = _data1;
+                        lastInputVelocity = _data2;
+                    } else {
+                        // Serial.print(F("Note Off CH"));
+                        // Serial.print(channel);
+                        // Serial.print(F(": "));
+                        // Serial.println(_data1);
+                        if (lastInputNote == _data1) {
+                            lastInputNote = -1; // Note On vel 0 is Note Off
+                            lastInputVelocity = 0;
+                        }
+                    }
+                } else if (type == 0x80) {
+                    // Serial.print(F("Note Off CH"));
+                    // Serial.print(channel);
+                    // Serial.print(F(": "));
+                    // Serial.println(_data1);
+                    if (lastInputNote == _data1) {
+                        lastInputNote = -1;
+                        lastInputVelocity = 0;
+                    }
+                }
+            }
+        }
+    }
+}
+
 void MidiDriver::lock() {
     mutex_enter_blocking(&_mutex);
 }

MidiDriver.h

@@ -8,6 +8,10 @@ class MidiDriver {
 public:
     MidiDriver();
     void begin();
+    void update();
+
+    volatile int lastInputNote;
+    volatile int lastInputVelocity;
     
     void sendNoteOn(uint8_t note, uint8_t velocity, uint8_t channel);
     void sendNoteOff(uint8_t note, uint8_t channel);
@@ -19,6 +23,10 @@ public:
 
 private:
     mutex_t _mutex;
+    uint8_t _runningStatus;
+    uint8_t _byteIndex;
+    uint8_t _data1;
+    uint8_t _data2;
 };
 
 extern MidiDriver midi;

PlaybackThread.cpp

@@ -129,6 +129,7 @@ static void handlePlayback() {
 }
 
 void loopPlayback() {
+  midi.update();
   if (needsPanic) {
     for (int i=0; i<NUM_TRACKS; i++) {
       midi.panic(midiChannels[i]);

README.md

@@ -50,13 +50,16 @@ Make sure to establish a **common ground** by connecting the ground from your ex
 |   GND                | External 5V Supply -   | External Power Ground       |
 |   (Matrix GND)       | GND (Pin 18)           | Common Ground with Pico     |
 +----------------------+------------------------+-----------------------------+
-| MIDI DIN (Serial)    |                        |                             |
+| MIDI OUT (Serial)    |                        |                             |
 |   TX (MIDI OUT)      | GP0 (Pin 1)            | To DIN Pin 5 (via 220 ohm)  |
+| MIDI IN (Serial)     |                        | (optional!)                 |
+|   RX (MIDI IN)       | GP1 (Pin 2)            | To DIN Pin 3 (optoisolator) |
 +----------------------+------------------------+-----------------------------+
 
 
 **MIDI Hardware Note**:
 *   **MIDI OUT**: Connect **GP0** to DIN Pin 5 via a 220Ω resistor. Connect DIN Pin 4 to 3.3V (3V3) via a 220Ω resistor. Connect DIN Pin 2 to GND.
+*   **MIDI IN**: Optional! Uses a 6N137 optocoupler based on [this guide](https://www.kieranreck.co.uk/MIDI-6N137-vs-6N138-vs-6N139/). Connect the optocoupler output to **GP1**.
 
 Once everything is wired up, you can upload the code and your tracker should be ready to go!