diff --git a/animus-3/source/animus/..arduino.samd.arduino_zero_native.bin b/animus-3/source/animus/..arduino.samd.arduino_zero_native.bin
deleted file mode 100755
index aa9feed..0000000
Binary files a/animus-3/source/animus/..arduino.samd.arduino_zero_native.bin and /dev/null differ
diff --git a/animus-3/source/animus/..arduino.samd.arduino_zero_native.elf b/animus-3/source/animus/..arduino.samd.arduino_zero_native.elf
deleted file mode 100755
index 55dea7b..0000000
Binary files a/animus-3/source/animus/..arduino.samd.arduino_zero_native.elf and /dev/null differ
diff --git a/animus-3/source/animus/Global.h b/animus-3/source/animus/Global.h
index e2050f2..2c47ae7 100644
--- a/animus-3/source/animus/Global.h
+++ b/animus-3/source/animus/Global.h
@@ -1,5 +1,7 @@
 #define DEFAULT_ROW 12
 #define DEFAULT_COL 12
+#define I2C_HOST_ADDRESS 7
+#define I2C_GUEST_ADDRESS 8
 
 #ifndef ANIMUS_GLOBAL
 #define ANIMUS_GLOBAL
diff --git a/animus-3/source/animus/ModI2CGuest.cpp b/animus-3/source/animus/ModI2CGuest.cpp
index 64df909..05e712b 100644
--- a/animus-3/source/animus/ModI2CGuest.cpp
+++ b/animus-3/source/animus/ModI2CGuest.cpp
@@ -12,79 +12,79 @@ void CModI2CGuest::Begin(void) //TODO add method to return entire EEPROM to host
 
   if (!Global.HasUSB) // if no usb
   {
-    Wire.begin(8);
-    Wire.onRequest([] {ModI2CGuest.OnRequest();});
-    Wire.onReceive([] (int numBytes) {ModI2CGuest.OnReceive(numBytes);});
-  }
-}
-
-void CModI2CGuest::OnRequest()
-{
-  if (SlaveIndex == 0) // if slave array is empty, add single byte
-  {
-    Wire.write(0);
+    isMaster = false;
+    SetMaster(true);
   }
-  Wire.write(SlaveArray, SlaveIndex);
-  SlaveIndex = 0;
 }
 
 void CModI2CGuest::OnReceive(int numBytes)
 {
+  byte errorOffset = 0;
 
-  byte type = Wire.read();
-  if (type == 1) // received templay
-  {
-    byte input = Wire.read();
-    Global.TempLayer = input;
-  }
-  else if (type == 2) // setEEPROM
+  while (Wire.available())
   {
+    byte type = Wire.read();
 
-    byte byteA = Wire.read();
-    byte byteB = Wire.read();
-    short startAddr = (byteA << 8) | byteB;
-    while (Wire.available())
+    if (type == 1) // received templay
     {
-      PersMem.SetEEPROM(startAddr, Wire.read());
-      startAddr++;
+      byte input = Wire.read();
+      Global.TempLayer = input;
     }
-    PersMem.CommitEEPROM();
-  }
-  else if (type == 3) // return part of the EEPROM
-  {
-    byte byteA = Wire.read();
-    byte byteB = Wire.read();
-    short startAddr = (byteA << 8) | byteB;
-    SlaveIndex = 0;
-    while (SlaveIndex < 32 && startAddr < MEM_EEPROM_SIZE)
+    else if (type == 2) // setEEPROM
     {
-      SlaveArray[SlaveIndex] = PersMem.GetEEPROM(startAddr);
-      SlaveIndex++;
-      startAddr++;
+      byte byteA = Wire.read();
+      byte byteB = Wire.read();
+      for (short i = (byteA << 8) | byteB; i < MEM_EEPROM_SIZE && Wire.available(); i++)
+      {
+        PersMem.SetEEPROM(i, Wire.read());
+      }
+      PersMem.CommitEEPROM();
     }
-  }
-  else if (type == 4) // update brightness
-  {
-    Global.LEDBrightness = Wire.read();
-  }
-  else if (type == 5) // update keyboard delays
-  {
-    Global.KeyDownDelay = Wire.read();
-    Global.KeyUpDelay = Wire.read();
-  }
-  else if (type == 6) // resend for erreneous key
-  {
-    byte x = Wire.read();
-    byte y = Wire.read();
-    Global.LayerState[x][y] = Global.TempLayer;
-    if (SlaveIndex < 32)
+    else if (type == 3) // return part of the EEPROM
     {
-      SlaveArray[SlaveIndex] = PersMem.GetKeyData(x, y, Global.TempLayer);
-      SlaveIndex++;
-      SlaveArray[SlaveIndex] = PersMem.GetKeyType(x, y, Global.TempLayer);
-      SlaveIndex++;
+      byte byteA = Wire.read();
+      byte byteB = Wire.read();
+      SlaveIndex = 0;
+      for (short i = (byteA << 8) | byteB; i < MEM_EEPROM_SIZE; i++)
+      {
+        SlaveArray[SlaveIndex] = PersMem.GetEEPROM(i);
+        SlaveIndex++;
+      }
+    }
+    else if (type == 4) // update brightness
+    {
+      Global.LEDBrightness = Wire.read();
+    }
+    else if (type == 5) // update refresh rate
+    {
+      Global.KeyDownDelay = Wire.read();
+      Global.KeyUpDelay   = Wire.read();
+    }
+    else if (type == 6) // erreneous key
+    {
+      byte x = Wire.read();
+      byte y = Wire.read();
+      Global.LayerState[x][y] = Global.TempLayer;
+
+      if (32 - SlaveIndex >= 3)
+      {
+        // We want all erreneous keys to appear before any keypresses that might have
+        // occured, in chronological order.
+        if (SlaveIndex > 0)
+        {
+          memcpy(SlaveArray + errorOffset + 3, SlaveArray + errorOffset, SlaveIndex - errorOffset);
+        }
+        SlaveArray[errorOffset + 0] = PersMem.GetKeyData(x, y, Global.TempLayer);
+        SlaveArray[errorOffset + 1] = PersMem.GetKeyType(x, y, Global.TempLayer);
+        SlaveArray[errorOffset + 2] = 5;
+        SlaveIndex += 3;
+        errorOffset += 3;
+      }
     }
   }
+
+  SetMaster(true);
+  pullTimeout = 0;
 }
 
 void CModI2CGuest::LoadData(void)
@@ -101,12 +101,25 @@ void CModI2CGuest::Loop(void)
 {
   CModTemplate::Loop();
 
-  if (Animus.Async1MSDelay())
+  if (!Global.HasUSB && isMaster)
   {
-
-    if (Global.HasUSB)
+    if (SlaveIndex > 0)
     {
-
+      Wire.beginTransmission(I2C_HOST_ADDRESS);
+      Wire.write(SlaveArray, SlaveIndex);
+      Wire.endTransmission();
+      SlaveIndex = 0;
+      SetMaster(false);
+    }
+    else if (Animus.Async1MSDelay())
+    {
+      pullTimeout++;
+      if (pullTimeout >= PULL_RATE) // Send an empty message to pull updates from the host
+      {
+        Wire.beginTransmission(I2C_HOST_ADDRESS);
+        Wire.endTransmission();
+        SetMaster(false);
+      }
     }
   }
 }
@@ -187,4 +200,23 @@ void CModI2CGuest::SerialComms(byte mode)
 }
 
 
+void CModI2CGuest::SetMaster(bool value)
+{
+  if (isMaster == value) return;
+
+  isMaster = value;
+  Wire.end();
+
+  if (value)
+  {
+    Wire.begin();
+    Wire.onReceive([] (int numBytes) {ModI2CGuest.OnReceive(numBytes);});
+  }
+  else
+  {
+    Wire.begin(I2C_GUEST_ADDRESS);
+  }
+}
+
+
 CModI2CGuest ModI2CGuest;
diff --git a/animus-3/source/animus/ModI2CGuest.h b/animus-3/source/animus/ModI2CGuest.h
index 1d8e493..8a951ba 100644
--- a/animus-3/source/animus/ModI2CGuest.h
+++ b/animus-3/source/animus/ModI2CGuest.h
@@ -4,11 +4,15 @@
 #include "Animus.h"
 #include "Wire.h"
 
+#define PULL_RATE 50
+
 class CModI2CGuest : public CModTemplate
 {
 private:
   byte SlaveArray[32];
   byte SlaveIndex = 0;
+  bool isMaster = false;
+  byte pullTimeout = 0;
 public:
   CModI2CGuest(void);
   void Begin(void);
@@ -18,11 +22,11 @@ class CModI2CGuest : public CModTemplate
   void PrePress(byte val, byte type);
   void PressKey(byte val, byte type);
   void ReleaseKey(byte val, byte type);
-  void OnRequest();
   void OnReceive(int numBytes);
   static void RequestEvent();
   static void ReceiveEvent(int numBytes);
   void SerialComms(byte mode);
+  void SetMaster(bool value);
 };
 extern CModI2CGuest ModI2CGuest;
 
diff --git a/animus-3/source/animus/ModI2CHost.cpp b/animus-3/source/animus/ModI2CHost.cpp
index d1b5fe8..3395fc1 100644
--- a/animus-3/source/animus/ModI2CHost.cpp
+++ b/animus-3/source/animus/ModI2CHost.cpp
@@ -11,7 +11,8 @@ void CModI2CHost::Begin(void)
 
   if (Global.HasUSB) // i2c host only activates if this device is plugged into the PC
   {
-    Wire.begin();
+    isMaster = true;
+    SetMaster(false);
   }
 }
 
@@ -28,127 +29,6 @@ void CModI2CHost::LoadData(void)
 
 void CModI2CHost::Loop(void)
 {
-  CModTemplate::Loop();
-
-  if (Global.HasUSB)
-  {
-    // syncs templayer value with guest
-    if (Global.TempLayer != I2CTempLayer)
-    {
-      SetTempLayer();
-      I2CTempLayer = Global.TempLayer;
-    }
-    if (Global.LEDBrightness != I2CLEDBrightness)
-    {
-      SetSubLEDBrightness();
-      I2CLEDBrightness = Global.LEDBrightness;
-    }
-    if (Global.KeyDownDelay != I2CKeyDown || Global.KeyUpDelay != I2CKeyUp)
-    {
-      SetSubKeyboardDelay();
-      I2CKeyUp = Global.KeyDownDelay;
-      I2CKeyDown = Global.KeyUpDelay;
-    }
-    // gets keystrokes from guest
-    Wire.requestFrom(8, 32);
-    bool hasInput = true;
-    byte keyData[8];
-    byte keyType[8];
-    byte keyMode[8];
-    byte keyX[8];
-    byte keyY[8];
-    byte keyIndex = 0;
-    while (hasInput)
-    {
-
-      if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-      {
-        // gets XY coords for pressed key
-        byte tempByte = Wire.read();
-        keyX[keyIndex] = tempByte & 0x0f; // bitwise structure is YYYYXXXX
-        keyY[keyIndex] = tempByte >> 4;
-      }
-      else
-      {
-        hasInput = false;
-      }
-
-      if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-      {
-        keyData[keyIndex] = Wire.read();
-      }
-      else
-      {
-        hasInput = false;
-      }
-
-      if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-      {
-        keyType[keyIndex] = Wire.read();
-      }
-      else
-      {
-        hasInput = false;
-      }
-
-      if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-      {
-        keyMode[keyIndex] = Wire.read();
-        keyIndex++;
-      }
-      else
-      {
-        hasInput = false;
-      }
-    }
-
-    for (byte i = 0; i < keyIndex; i++)
-    {
-
-      if (keyMode[i] == 1) // release key
-      {
-        Animus.ReleaseKey(keyData[i], keyType[i]);
-      }
-      else if (keyMode[i] == 5) // press key
-      {
-        Animus.PrePress(keyData[i], keyType[i]);
-        if (Global.TempLayer != I2CTempLayer)
-        {
-          SetTempLayer();
-          I2CTempLayer = Global.TempLayer;
-          Wire.beginTransmission(8);
-          Wire.write(6);
-          Wire.write(keyX[i]);
-          Wire.write(keyY[i]);
-          Wire.endTransmission();
-          Wire.requestFrom(8, 2);
-          if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-          {
-            keyData[i] = Wire.read();
-          }
-          if (Wire.available()) // need to put ifs in here so trailing bytes are left out
-          {
-            keyType[i] = Wire.read();
-          }
-        }
-        Animus.PressKey(keyData[i], keyType[i]);
-      }
-    }
-  }
-
-
-
-  if (Animus.Async1MSDelay())
-  {
-
-    if (Global.HasUSB)
-    {
-
-    }
-  }
-
-
-
 }
 
 void CModI2CHost::PressCoords(byte x, byte y)
@@ -198,7 +78,7 @@ void CModI2CHost::SerialComms(byte mode) // holy shit this is complicated
   {
     if (Comms.mode == 6) // write to guest eeprom starting at addr = 0 or MEM_BOARD_TYPE, ending at first short read from serial
     {
-      if (Serial.available()) //TODO I might want to work in a timeout or fail check for this
+      if (Serial.available()) // TODO I might want to work in a timeout or fail check for this
       {
         if (SerialLoaderByteStatus == 0) // if this is the first time mode 6 has made contact
         {
@@ -227,9 +107,7 @@ void CModI2CHost::SerialComms(byte mode) // holy shit this is complicated
           }
           if (EEPROMPacketSize <= 0)
           {
-            SetSubEEPROM();
-            EEPROMPacketIndex = 2;
-            SerialLoaderByteStatus = 0;
+            pendingEEPROMUpdate = true;
             Comms.mode = 0;
           }
         }
@@ -238,10 +116,10 @@ void CModI2CHost::SerialComms(byte mode) // holy shit this is complicated
     else if (Comms.mode == 7) // request read sub EEPROM
     {
       short addr = 0;
-      while(addr < MEM_EEPROM_SIZE)
+      while (addr < MEM_EEPROM_SIZE)
       {
-        GetSubEEPROM(addr);
-        Wire.requestFrom(8, 32);
+        GetSubEEPROM(addr); // TODO
+        Wire.requestFrom(I2C_GUEST_ADDRESS, 32);
         while(Wire.available())
         {
           Serial.println(Wire.read());
@@ -258,18 +136,14 @@ void CModI2CHost::SerialComms(byte mode) // holy shit this is complicated
 
 void CModI2CHost::SetTempLayer()
 {
-  Wire.beginTransmission(8);
   Wire.write(1);
   Wire.write(Global.TempLayer);
-  Wire.endTransmission();
 }
 
 void CModI2CHost::SetSubEEPROM(void)
 {
-  Wire.beginTransmission(8);
   Wire.write(2);
   Wire.write(EEPROMPacket, EEPROMPacketIndex);
-  Wire.endTransmission();
 }
 
 void CModI2CHost::GetSubEEPROM(short startAddr)
@@ -285,21 +159,115 @@ void CModI2CHost::GetSubEEPROM(short startAddr)
 
 void CModI2CHost::SetSubLEDBrightness(void)
 {
-  Wire.beginTransmission(8);
   Wire.write(4);
   Wire.write(Global.LEDBrightness);
-  Wire.endTransmission();
 }
 
 void CModI2CHost::SetSubKeyboardDelay(void)
 {
-  Wire.beginTransmission(8);
   Wire.write(5);
   Wire.write(Global.KeyDownDelay);
   Wire.write(Global.KeyUpDelay);
+}
+
+
+
+void CModI2CHost::OnReceive(int numBytes)
+{
+  SetMaster (true);
+  Wire.beginTransmission(I2C_GUEST_ADDRESS);
+
+  // Parse package
+  byte buffer[numBytes];
+  Wire.readBytes(buffer, numBytes);
+
+  byte keyData[8];
+  byte keyType[8];
+  byte keyMode[8];
+  byte keyX[8];
+  byte keyY[8];
+  byte keyIndex = 0;
+
+  for (int i = 0; i < numBytes; i+=4, keyIndex++)
+  {
+    keyX[keyIndex]    = buffer[i+0] & 0x0f; // bitwise structure is YYYYXXXX
+    keyY[keyIndex]    = buffer[i+0] >> 4;
+    keyData[keyIndex] = buffer[i+1];
+    keyType[keyIndex] = buffer[i+2];
+    keyMode[keyIndex] = buffer[i+3];
+  }
+
+  // Execute keypresses
+  for (byte i = 0; i < keyIndex; i++)
+  {
+    if (keyMode[i] == 1) // release key
+    {
+      Animus.ReleaseKey(keyData[i], keyType[i]);
+    }
+    else if (keyMode[i] == 5) // press key
+    {
+      if (Global.TempLayer != I2CTempLayer) // Wrong layout!
+      {
+        SetTempLayer();
+        I2CTempLayer = Global.TempLayer;
+        Wire.write(6);
+        Wire.write(keyX[i]);
+        Wire.write(keyY[i]);
+      }
+      else
+      {
+        Animus.PrePress(keyData[i], keyType[i]);
+        Animus.PressKey(keyData[i], keyType[i]);
+      }
+    }
+  }
+
+  // Send updates
+  if (Global.TempLayer != I2CTempLayer)
+  {
+    SetTempLayer();
+    I2CTempLayer = Global.TempLayer;
+  }
+  if (Global.LEDBrightness != I2CLEDBrightness)
+  {
+    SetSubLEDBrightness();
+    I2CLEDBrightness = Global.LEDBrightness;
+  }
+  if (Global.KeyDownDelay != I2CKeyDown || Global.KeyUpDelay != I2CKeyUp)
+  {
+    SetSubKeyboardDelay();
+    I2CKeyDown = Global.KeyDownDelay;
+    I2CKeyUp = Global.KeyUpDelay;
+  }
+  if (pendingEEPROMUpdate)
+  {
+    SetSubEEPROM();
+    EEPROMPacketIndex = 2;
+    SerialLoaderByteStatus = 0;
+    pendingEEPROMUpdate = false;
+  }
+
   Wire.endTransmission();
+  SetMaster(false);
 }
 
+void CModI2CHost::SetMaster(bool value)
+{
+  if (isMaster == value) return;
+
+  isMaster = value;
+  Wire.end();
+
+  if (value)
+  {
+    Wire.begin();
+  }
+  else
+  {
+    Wire.begin(I2C_HOST_ADDRESS);
+    Wire.onReceive([] (int numBytes) {ModI2CHost.OnReceive(numBytes);});
+  }
+}
 
 
 CModI2CHost ModI2CHost;
diff --git a/animus-3/source/animus/ModI2CHost.h b/animus-3/source/animus/ModI2CHost.h
index ad93315..d5a59da 100644
--- a/animus-3/source/animus/ModI2CHost.h
+++ b/animus-3/source/animus/ModI2CHost.h
@@ -28,12 +28,16 @@ class CModI2CHost : public CModTemplate
   byte I2CKeyUp = 0;
   byte SerialLoaderByteStatus = 0;
   byte EEPROMPacketSize = 0;
+  bool isMaster = false;
+  bool pendingEEPROMUpdate = false;
   void SetTempLayer(void);
   void SetSubEEPROM(void);
   void SetSubBoardSettings(void);
   void SetSubLEDBrightness(void);
   void SetSubKeyboardDelay(void);
   void GetSubEEPROM(short startAddr);
+  void OnReceive(int numBytes);
+  void SetMaster(bool value);
 
 
 public: