FW: added midi in and out related code

Software/Gravity/Gravity.ino

@@ -108,11 +108,12 @@ unsigned int pulsePeriod;
 bool isPlaying = false;
 bool isRecording = false;
 bool recordToNextStep = false;
+bool MIDIClockRecived = false;
 
 unsigned int tickCount = 0;
 unsigned int pulseCount = 0;
 
-byte masterClockMode = 0;  // 0 - internal, 1 - external 24ppqn, 2 - external beat
+byte masterClockMode = 0;  // 0 - internal, 1 - external 24ppqn, 2 - MIDI
 unsigned long lastExtPulseTime;
 unsigned long newExtPulseTime;
 
@@ -216,6 +217,23 @@ void loop() {
 void sendMIDIClock() {
   Serial.write(0xF8);
 }
+void sendMIDIStart() {
+  Serial.write(0xFA);
+}
+void sendMIDIStop() {
+  Serial.write(0xFC);
+}
+void receiveMIDI() {
+  if(Serial.available() > 0) {
+    if (Serial.read() == 0xF8) { //Clock
+      MIDIClockRecived = true;
+    } else if (Serial.read() == 0xFA || Serial.read() == 0xFB) { //start and continue
+      isPlaying = true;
+    } else if (Serial.read() == 0xFC) { //stop
+      isPlaying = false;
+    } 
+  }
+}
 
 void clock() {
   if (isPlaying) {
@@ -244,6 +262,16 @@ void clock() {
       }
     }
 
+    if (masterClockMode == 2 && MIDIClockRecived) {  // MIDI should happen here (needs testing)
+      tickCount = 0;  //to make things happen in the main clock function
+      if (pulseCount < (PPQN - 1)) {
+        pulseCount++;
+      } else {
+        pulseCount = 0;
+      }
+      MIDIClockRecived = false;
+    }
+
     // pull low all outputs after set pulse length
     if (tickCount >= PULSE_LENGTH) {
       for (byte i = 0; i < 6; i++) {
@@ -275,8 +303,7 @@ void externalClock() {
     } else {
       pulseCount = 0;
     }
-
-  }
+  } 
 }
 
 void sendTriggers() {