Consistent clock behavior for ext cv and midi.

clock.h

@@ -24,7 +24,10 @@
 #define MIDI_CONTINUE 0xFB
 
 const int DEFAULT_TEMPO = 120;
-static bool MIDI_ENABLED = false;
+
+typedef void (*ExtCallback)(void);
+static ExtCallback extUserCallback = nullptr;
+static void serialEventNoop(uint8_t msg, uint8_t status) {}
 
 enum Source {
     SOURCE_INTERNAL,
@@ -38,12 +41,12 @@ class Clock {
    public:
     void Init() {
         NeoSerial.begin(31250);
-        NeoSerial.attachInterrupt(onSerialEvent);
 
         // Static pin definition for pulse out.
         pinMode(PULSE_OUT_PIN, OUTPUT);
 
         // Initialize the clock library
+        uClock.setExtIntervalBuffer(32);
         uClock.init();
         uClock.setClockMode(uClock.INTERNAL_CLOCK);
         uClock.setOutputPPQN(uClock.PPQN_96);
@@ -52,14 +55,15 @@ class Clock {
         // MIDI events.
         uClock.setOnClockStart(sendMIDIStart);
         uClock.setOnClockStop(sendMIDIStop);
-        uClock.setOnSync24(sendMidiClock);
+        uClock.setOnSync24(sendMIDIClock);
         uClock.setOnSync48(sendPulseOut);
 
         uClock.start();
     }
 
-    // Handler for receiving clock trigger(PPQN_4 or PPQN_24).
+    // Handle external clock tick and call user callback when receiving clock trigger (PPQN_4, PPQN_24, or MIDI).
-    void AttachExtHandler(void (*callback)(void)) {
+    void AttachExtHandler(void (*callback)()) {
+        extUserCallback = callback;
         attachInterrupt(digitalPinToInterrupt(EXT_PIN), callback, RISING);
     }
 
@@ -70,8 +74,13 @@ class Clock {
 
     // Set the source of the clock mode.
     void SetSource(Source source) {
+        bool was_playing = !IsPaused();
         uClock.stop();
-        MIDI_ENABLED = false;
+        // If source is currently MIDI, disable the serial interrupt handler.
+        if (source_ == SOURCE_EXTERNAL_MIDI) {
+            NeoSerial.attachInterrupt(serialEventNoop);
+        }
+        source_ = source;
         switch (source) {
             case SOURCE_INTERNAL:
                 uClock.setClockMode(uClock.INTERNAL_CLOCK);
@@ -87,52 +96,64 @@ class Clock {
             case SOURCE_EXTERNAL_MIDI:
                 uClock.setClockMode(uClock.EXTERNAL_CLOCK);
                 uClock.setInputPPQN(uClock.PPQN_24);
-                MIDI_ENABLED = true;
+                NeoSerial.attachInterrupt(onSerialEvent);
                 break;
         }
-        uClock.start();
+        if (was_playing) {
+            uClock.start();
+        }
     }
 
+    // Return true if the current selected source is externl (PPQN_4, PPQN_24, or MIDI).
     bool ExternalSource() {
         return uClock.getClockMode() == uClock.EXTERNAL_CLOCK;
     }
 
+    // Return true if the current selected source is the internal master clock.
     bool InternalSource() {
         return uClock.getClockMode() == uClock.INTERNAL_CLOCK;
     }
 
+    // Returns the current BPM tempo.
     int Tempo() {
         return uClock.getTempo();
     }
 
+    // Set the clock tempo to a int between 1 and 400.
     void SetTempo(int tempo) {
         return uClock.setTempo(tempo);
     }
 
+    // Record an external clock tick received to process external/internal syncronization.
     void Tick() {
         uClock.clockMe();
     }
 
-    void Pause() {
+    // Start the internal clock.
-        uClock.pause();
+    void Start() {
-    }
-
-    void Reset() {
         uClock.start();
     }
 
+    // Stop internal clock clock.
+    void Stop() {
+        uClock.stop();
+    }
+
+    // Returns true if the clock is not running.
     bool IsPaused() {
         return uClock.clock_state == uClock.PAUSED;
     }
 
    private:
+    Source source_ = SOURCE_INTERNAL;
+
     static void onSerialEvent(uint8_t msg, uint8_t status) {
-        // if (!MIDI_ENABLED) {
+        // Note: uClock start and stop will echo to MIDI.
-        //     return;
-        // }
         switch (msg) {
             case MIDI_CLOCK:
-                uClock.clockMe();
+                if (extUserCallback) {
+                    extUserCallback();
+                }
                 break;
             case MIDI_STOP:
                 uClock.stop();
@@ -141,7 +162,6 @@ class Clock {
             case MIDI_CONTINUE:
                 uClock.start();
                 break;
-            
         }
     }
 
@@ -153,7 +173,7 @@ class Clock {
         NeoSerial.write(MIDI_STOP);
     }
 
-    static void sendMidiClock(uint32_t tick) {
+    static void sendMIDIClock(uint32_t tick) {
         NeoSerial.write(MIDI_CLOCK);
     }
 

examples/clock_mod/clock_mod.ino

@@ -13,7 +13,7 @@
  *
  * BTN1: Play/pause the internal clock.
  *
- * BTN2: Reset all clocks.
+ * BTN2: Stop all clocks.
  *
  */
 
@@ -68,8 +68,8 @@ void setup() {
     gravity.Init();
 
     // Clock handlers.
-    gravity.clock.AttachExtHandler(ExtClock);
+    gravity.clock.AttachIntHandler(HandleIntClockTick);
-    gravity.clock.AttachIntHandler(IntClock);
+    gravity.clock.AttachExtHandler(HandleExtClockTick);
 
     // Encoder rotate and press handlers.
     gravity.encoder.AttachPressHandler(HandleEncoderPressed);
@@ -95,16 +95,9 @@ void loop() {
 // Firmware handlers.
 //
 
-void ExtClock() {
+void HandleIntClockTick(uint32_t tick) {
-    if (gravity.clock.ExternalSource()) {
-        gravity.clock.Tick();
-        app.refresh_screen = true;
-    }
-}
-
-void IntClock(uint32_t tick) {
     for (int i = 0; i < OUTPUT_COUNT; i++) {
-        const auto& channel = app.channel[i];
+        auto& channel = app.channel[i];
         auto& output = gravity.outputs[i];
 
         const uint32_t mod_pulses = clock_mod_pulses[channel.clock_mod_index];
@@ -126,18 +119,27 @@ void IntClock(uint32_t tick) {
     }
 }
 
-void HandlePlayPressed() {
+void HandleExtClockTick() {
-    gravity.clock.Pause();
+    // Ignore tick if not using external source.
-    if (gravity.clock.IsPaused()) {
+    if (!gravity.clock.ExternalSource()) {
-        for (int i = 0; i < OUTPUT_COUNT; i++) {
+        return;
-            gravity.outputs[i].Low();
-        }
     }
+    gravity.clock.Tick();
+    app.refresh_screen = true;
+}
+
+void HandlePlayPressed() {
+    gravity.clock.IsPaused() 
+        ? gravity.clock.Start() 
+        : gravity.clock.Stop();
+    ResetOutputs();
     app.refresh_screen = true;
 }
 
 void HandleShiftPressed() {
-    gravity.clock.Reset();
+    gravity.clock.Stop();
+    ResetOutputs();
+    app.refresh_screen = true;
 }
 
 void HandleEncoderPressed() {
@@ -228,6 +230,12 @@ Channel& GetSelectedChannel() {
     return app.channel[app.selected_channel - 1];
 }
 
+void ResetOutputs() {
+    for (int i = 0; i < OUTPUT_COUNT; i++) {
+        gravity.outputs[i].Low();
+    }
+}
+
 //
 // UI Display functions.
 //

gravity.cpp

@@ -12,17 +12,17 @@
 #include "gravity.h"
 
 void Gravity::Init() {
-    InitClock();
+    initClock();
-    InitInputs();
+    initInputs();
-    InitOutputs();
+    initOutputs();
-    InitDisplay();
+    initDisplay();
 }
 
-void Gravity::InitClock() {
+void Gravity::initClock() {
     clock.Init();
 }
 
-void Gravity::InitInputs() {
+void Gravity::initInputs() {
     shift_button.Init(SHIFT_BTN_PIN);
     play_button.Init(PLAY_BTN_PIN);
 
@@ -40,7 +40,7 @@ void Gravity::InitInputs() {
     PCMSK1 |= B00001000;
 }
 
-void Gravity::InitOutputs() {
+void Gravity::initOutputs() {
     // Initialize each of the outputs with it's GPIO pins and probability.
     outputs[0].Init(OUT_CH1);
     outputs[1].Init(OUT_CH2);
@@ -49,7 +49,7 @@ void Gravity::InitOutputs() {
     outputs[4].Init(OUT_CH5);
     outputs[5].Init(OUT_CH6);
 }
-void Gravity::InitDisplay() {
+void Gravity::initDisplay() {
     // OLED Display configuration.
     display.begin();
 }

gravity.h

@@ -37,10 +37,10 @@ class Gravity {
     AnalogInput cv2;
 
    private:
-    void InitClock();
+    void initClock();
-    void InitDisplay();
+    void initDisplay();
-    void InitInputs();
+    void initInputs();
-    void InitOutputs();
+    void initOutputs();
 };
 
 extern Gravity gravity;