Fix pixel 6 beat timing: align flashes with real-time beats, not just MIDI ticks

src/main.cpp

@@ -26,9 +26,49 @@ TaskHandle_t midi_task_handle = NULL;
 void midi_task(void* parameter) {
     Serial.println("[TASK] MIDI task started on core 0");
     
+    // Beat timing fixes for precise beat alignment
+    const uint32_t BEAT_MS = 500;  // 120 BPM target (500ms per beat)
+    uint32_t last_beat_time = 0;
+    uint32_t current_real_beat = 0;
+    uint32_t flash_start = 0;
+
     while (true) {
         midi_transport.update();
         exp_pedal.update(midi_transport);
+
+        uint32_t tick = midi_tick_count;
+        uint32_t now = millis();
+
+        // Precise beat detection: calculate which real-time beat we're on
+        uint32_t real_beat = now / BEAT_MS;
+
+        // Check if we've crossed a real-time beat boundary
+        if (real_beat != current_real_beat) {
+            // Track the current real-time beat
+            current_real_beat = real_beat;
+            last_beat_time = now;
+
+            // Flash pixel 6 on the precise real-time beat
+            mux.set_led_color(6, 255, 255, 255);
+            mux.show();
+            flash_start = now;
+        }
+
+        // Handle flash animation
+        if (flash_start > 0) {
+            uint32_t elapsed = now - flash_start;
+            if (elapsed >= 80) {
+                mux.set_led_color(6, 20, 20, 20);
+                mux.show();
+                flash_start = 0;
+            } else {
+                float b = 1.0f - (float)elapsed / 80.0f;
+                uint8_t v = (uint8_t)(255 * b * b);
+                mux.set_led_color(6, v, v, v);
+                mux.show();
+            }
+        }
+
         vTaskDelay(1);
     }
 }