Added CV and Gate outputs via 2x i2c MCP4725 modules

MidiExternalSync.ino

@@ -0,0 +1,55 @@
+// MIDI clock, start, stop, note on and note off byte definitions - based on MIDI 1.0 Standards.
+#define MIDI_CLOCK 0xF8
+#define MIDI_START 0xFA
+#define MIDI_STOP  0xFC
+
+byte in_data = 0X00;
+
+// avr general timer2 - 8bits
+// 250usecs timmer to read midi input clock/control messages
+void setExternalSync(bool on)
+{
+  if (on == true) {
+    noInterrupts();
+    TCCR2A = 0; // set entire TCCR2A register to 0
+    TCCR2B = 0; // same for TCCR2B
+    TCNT2  = 0; // initialize counter value to 0
+    // set compare match register for 4000 Hz increments
+    OCR2A = 124; // = 16000000 / (32 * 4000) - 1 (must be <256)
+    // turn on CTC mode
+    TCCR2B |= (1 << WGM21);
+    // Set CS22, CS21 and CS20 bits for 32 prescaler
+    TCCR2B |= (0 << CS22) | (1 << CS21) | (1 << CS20);
+    // enable timer compare interrupt
+    TIMSK2 |= (1 << OCIE2A);
+    interrupts();
+    uClock.setMode(uClock.EXTERNAL_CLOCK);
+  } else {
+    uClock.setMode(uClock.INTERNAL_CLOCK);
+    noInterrupts();
+    // disable timer compare interrupt
+    TIMSK2 |= (0 << OCIE2A);
+    interrupts();
+  }
+}
+
+ISR(TIMER2_COMPA_vect, ISR_NOBLOCK) 
+{
+  if(Serial.available() > 0) {
+    in_data = Serial.read();
+    switch (in_data) {
+        case MIDI_CLOCK:
+          uClock.clockMe();
+          return;
+        case MIDI_START:
+          uClock.start();
+          return;
+        case MIDI_STOP:
+          uClock.stop();
+          return;
+        default:
+          return;
+    }
+  } 
+}
+