diff --git a/left/src/config.h b/left/src/config.h
index fb65ff0..83e512b 100644
--- a/left/src/config.h
+++ b/left/src/config.h
@@ -3,6 +3,6 @@
 
 // Macros:
 
-    #define DEBUG_OVER_SPI
+//    #define DEBUG_OVER_SPI
 
 #endif
diff --git a/left/src/debug_over_spi.c b/left/src/debug_over_spi.c
index b161f6a..28752ed 100644
--- a/left/src/debug_over_spi.c
+++ b/left/src/debug_over_spi.c
@@ -14,7 +14,7 @@ static spi_transfer_t xfer = {0};
 static spi_master_config_t userConfig;
 spi_master_handle_t handle;
 
-static volatile bool masterFinished = false;
+static volatile bool masterFinished = true;
 
 #endif
 
@@ -51,12 +51,12 @@ void DebugOverSpi_Init(void)
 void DebugOverSpi_Send(uint8_t *tx, uint8_t len)
 {
 #ifdef DEBUG_OVER_SPI
-//    if (masterFinished) {
+    if (masterFinished) {
         masterFinished = false;
         memcpy(srcBuff, tx, MIN(BUFFER_SIZE, len));
         xfer.txData = srcBuff;
         xfer.dataSize = len;
         SPI_MasterTransferNonBlocking(EXAMPLE_SPI_MASTER, &handle, &xfer);
-//    }
+    }
 #endif
 }
diff --git a/left/src/init_peripherals.c b/left/src/init_peripherals.c
index f03562f..91172c0 100644
--- a/left/src/init_peripherals.c
+++ b/left/src/init_peripherals.c
@@ -14,16 +14,14 @@
 i2c_slave_config_t slaveConfig;
 i2c_slave_handle_t slaveHandle;
 
-uint8_t byteIn;
+uint8_t userData;
 uint8_t rxMessagePos;
-i2c_slave_transfer_event_t prevEvent;
-
 uint8_t dosBuffer[2];
 
-static void i2cSlaveCallback(I2C_Type *base, i2c_slave_transfer_t *xfer, void *userData)
+static void i2cSlaveCallback(I2C_Type *base, i2c_slave_transfer_t *xfer, void *userDataArg)
 {
     dosBuffer[0] = xfer->event;
-    dosBuffer[1] = byteIn;
+    dosBuffer[1] = userData;
     DebugOverSpi_Send(dosBuffer, 2);
 
     switch (xfer->event) {
@@ -32,29 +30,18 @@ static void i2cSlaveCallback(I2C_Type *base, i2c_slave_transfer_t *xfer, void *u
             xfer->data = (uint8_t*)&TxMessage;
             xfer->dataSize = TxMessage.length + I2C_MESSAGE_HEADER_LENGTH;
             break;
-        case kI2C_SlaveReceiveEvent:
-            if (prevEvent == kI2C_SlaveReceiveEvent) {
-                ((uint8_t*)&RxMessage)[rxMessagePos++] = byteIn;
-            } else {
-                rxMessagePos = 0;
-                memset(&RxMessage, 0, I2C_MESSAGE_MAX_TOTAL_LENGTH);
-            }
-
-            xfer->data = (uint8_t*)&byteIn;
-            xfer->dataSize = 1;
+        case kI2C_SlaveAddressMatchEvent:
+            rxMessagePos = 0;
             break;
-        case kI2C_SlaveCompletionEvent:
-            if (prevEvent == kI2C_SlaveReceiveEvent) {
-                ((uint8_t*)&RxMessage)[rxMessagePos] = byteIn;
-                RxMessage.length = rxMessagePos - I2C_MESSAGE_HEADER_LENGTH;
+        case kI2C_SlaveReceiveEvent:
+            ((uint8_t*)&RxMessage)[rxMessagePos++] = userData;
+            if (RxMessage.length == rxMessagePos-I2C_MESSAGE_HEADER_LENGTH) {
                 SlaveRxHandler();
             }
             break;
         default:
             break;
     }
-
-    prevEvent = xfer->event;
 }
 
 void InitInterruptPriorities(void)
@@ -80,9 +67,8 @@ void InitI2c(void)
     I2C_SlaveGetDefaultConfig(&slaveConfig);
     slaveConfig.slaveAddress = I2C_ADDRESS_LEFT_KEYBOARD_HALF_FIRMWARE;
     I2C_SlaveInit(I2C_BUS_BASEADDR, &slaveConfig);
-    I2C_SlaveTransferCreateHandle(I2C_BUS_BASEADDR, &slaveHandle, i2cSlaveCallback, NULL);
-    slaveHandle.eventMask |= kI2C_SlaveCompletionEvent;
-    I2C_SlaveTransferNonBlocking(I2C_BUS_BASEADDR, &slaveHandle, kI2C_SlaveCompletionEvent);
+    I2C_SlaveTransferCreateHandle(I2C_BUS_BASEADDR, &slaveHandle, i2cSlaveCallback, &userData);
+    I2C_SlaveTransferNonBlocking(I2C_BUS_BASEADDR, &slaveHandle, kI2C_SlaveAddressMatchEvent);
 }
 
 void InitLedDriver(void)
diff --git a/lib/KSDK_2.0_MKL03Z8xxx4 b/lib/KSDK_2.0_MKL03Z8xxx4
index ac55fc2..49e20a5 160000
--- a/lib/KSDK_2.0_MKL03Z8xxx4
+++ b/lib/KSDK_2.0_MKL03Z8xxx4
@@ -1 +1 @@
-Subproject commit ac55fc28ee6aa68cddcac00f6b76398cd8c0b541
+Subproject commit 49e20a57988572156b1df1c73c783c8e5e0dbb49