diff --git a/Config.h b/Config.h
index fb9f74d..986a243 100644
--- a/Config.h
+++ b/Config.h
@@ -60,6 +60,9 @@
 // Use separate mode pins to switch external filters/bandwidth for example
 // #define STM32F4_NUCLEO_MODE_PINS
 
+// For the VK6MST Pi3 Shield communicating over i2c. i2c address & speed defined in i2cTeensy.cpp
+// #define VK6MST_TEENSY_PI3_SHIELD_I2C
+
 // Pass RSSI information to the host
 // #define SEND_RSSI_DATA
 
diff --git a/I2CTeensy.cpp b/I2CTeensy.cpp
new file mode 100644
index 0000000..f034724
--- /dev/null
+++ b/I2CTeensy.cpp
@@ -0,0 +1,225 @@
+/*
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *   28-4-2017 Created for MMDVM Pi shield for Teensy by Chris Huitema
+ */
+
+#include "Config.h"
+#include "Globals.h"
+
+#if defined(VK6MST_TEENSY_PI3_SHIELD_I2C)
+
+#include <i2c_t3.h>   //available here https://github.com/nox771/i2c_t3 or maybe the normal wire will work #include <wire.h> justs need to test i guess
+
+#define I2C_ADDRESS   0x22
+#define I2C_SPEED     100000
+
+// Function prototypes
+void receiveEvent(size_t count);
+void requestEvent(void);
+
+#define TX_FIFO_SIZE 512U
+#define RX_FIFO_SIZE 512U
+
+volatile uint8_t  TXfifo[TX_FIFO_SIZE];
+volatile uint8_t  RXfifo[RX_FIFO_SIZE];
+volatile uint16_t TXfifohead, TXfifotail;
+volatile uint16_t RXfifohead, RXfifotail;
+
+// Init queues
+void TXfifoinit(void)
+{
+   TXfifohead = 0U;
+   TXfifotail = 0U;
+}
+
+void RXfifoinit()
+{
+   RXfifohead = 0U;
+   RXfifotail = 0U;
+}
+
+// How full is queue
+
+uint16_t TXfifolevel(void)
+{
+   uint32_t tail = TXfifotail;
+   uint32_t head = TXfifohead;
+
+   if (tail > head)
+      return TX_FIFO_SIZE + head - tail;
+   else
+      return head - tail;
+}
+
+uint16_t RXfifolevel(void)
+{
+   uint32_t tail = RXfifotail;
+   uint32_t head = RXfifohead;
+
+   if (tail > head)
+      return RX_FIFO_SIZE + head - tail;
+   else
+      return head - tail;
+}
+
+
+uint8_t TXfifoput(uint8_t next)
+{
+   if (TXfifolevel() < TX_FIFO_SIZE) {
+      TXfifo[TXfifohead] = next;
+
+      TXfifohead++;
+      if (TXfifohead >= TX_FIFO_SIZE)
+         TXfifohead = 0U;
+      return 1U;
+   } else {
+      return 0U; // signal an overflow occurred by returning a zero count
+   }
+}
+
+void I2Cbegin(void)
+{
+  // Setup for Slave mode, address 0x22, pins 18/19, external pullups, speed in hz
+  Wire.begin(I2C_SLAVE, I2C_ADDRESS, I2C_PINS_18_19, I2C_PULLUP_EXT, I2C_SPEED);
+
+    // register events
+    Wire.onReceive(receiveEvent);
+    Wire.onRequest(requestEvent);
+
+    // initialize the fifos
+    TXfifoinit();
+    RXfifoinit();
+}
+
+
+int I2Cavailable(void)
+{
+  if (RXfifolevel() > 0U)
+      return 1U;
+    else
+      return 0U;
+}
+
+
+uint8_t I2Cread(void)
+{
+  uint8_t data_c = RXfifo[RXfifotail];
+
+   RXfifotail++;
+   if (RXfifotail >= RX_FIFO_SIZE)
+      RXfifotail = 0U;
+
+   return data_c;
+}
+
+
+void I2Cwrite(const uint8_t* data, uint16_t length)
+{
+   for (uint16_t i = 0U; i < length; i++)
+      TXfifoput(data[i]);   //puts it in the fifo
+}
+
+//
+// handle Rx Event (incoming I2C data)
+//
+void receiveEvent(size_t count)
+{
+  for (uint16_t i = 0U; i < count; i++)
+  {
+    if (RXfifolevel() < RX_FIFO_SIZE) {
+      RXfifo[RXfifohead] = Wire.readByte();
+      if (RXfifo[RXfifohead] != -1){
+        RXfifohead++;
+        if (RXfifohead >= RX_FIFO_SIZE) RXfifohead = 0U;
+      }
+    } else {
+      Wire.readByte();                  // drop data if mem full.
+    }
+    
+  }
+}
+
+//
+// handle Tx Event (outgoing I2C data)
+//
+void requestEvent(void)
+{
+    if (TXfifolevel() > 0) {
+      if (Wire.write(TXfifo[TXfifotail])){  //write to i2c
+        TXfifotail++;
+        if (TXfifotail >= TX_FIFO_SIZE) TXfifotail = 0U;
+      }  
+    }
+}
+
+
+
+/************************************/
+
+void CSerialPort::beginInt(uint8_t n, int speed)
+{
+  switch (n) {
+    case 1U:
+      return I2Cbegin();
+    case 3U:
+      Serial3.begin(speed);
+      break;
+    default:
+      break;
+  }
+}
+
+int CSerialPort::availableInt(uint8_t n)
+{
+  switch (n) {
+    case 1U:
+      return I2Cavailable();
+    case 3U:
+      return Serial3.available();
+    default:
+      return false;
+  }
+}
+
+uint8_t CSerialPort::readInt(uint8_t n)
+{
+  switch (n) {
+    case 1U:
+      return I2Cread();
+    case 3U:
+      return Serial3.read();
+    default:
+      return 0U;
+  }
+}
+
+void CSerialPort::writeInt(uint8_t n, const uint8_t* data, uint16_t length, bool flush)
+{
+  switch (n) {
+    case 1U:
+      I2Cwrite(data, length);
+      break;
+    case 3U:
+      Serial3.write(data, length);
+      if (flush)
+        Serial3.flush();
+      break;
+    default:
+      break;
+  }
+}
+
+#endif
diff --git a/IOSTM.cpp b/IOSTM.cpp
index 701ebfa..e76fd65 100644
--- a/IOSTM.cpp
+++ b/IOSTM.cpp
@@ -419,6 +419,85 @@ EXT_CLK  PA15   input
 #define PIN_TX            GPIO_Pin_4
 #define PIN_TX_CH         DAC_Channel_1
 
+#elif defined(STM32F722_F7HAT)
+/*
+Pin definitions for MMDVM-F7Hat Pi-Hat F0DEI DB9MAT DF2ET board:
+
+PTT      PB14   output
+COSLED   PB13   output
+LED      PB12   output
+COS      PC0    input
+
+DSTAR    PB15   output
+DMR      PC6    output
+YSF      PC7    output
+P25      PC8    output
+NXDN     PC9    output
+
+RX       PA0    analog input
+RSSI     PA7    analog input
+TX       PA4    analog output
+
+EXT_CLK  PA15   input
+*/
+
+#define PIN_COS           GPIO_Pin_0
+#define PORT_COS          GPIOC
+#define RCC_Per_COS       RCC_AHB1Periph_GPIOC
+
+#define PIN_PTT           GPIO_Pin_14
+#define PORT_PTT          GPIOB
+#define RCC_Per_PTT       RCC_AHB1Periph_GPIOB
+
+#define PIN_COSLED        GPIO_Pin_13
+#define PORT_COSLED       GPIOB
+#define RCC_Per_COSLED    RCC_AHB1Periph_GPIOB
+
+#define PIN_LED           GPIO_Pin_12
+#define PORT_LED          GPIOB
+#define RCC_Per_LED       RCC_AHB1Periph_GPIOB
+
+#define PIN_P25           GPIO_Pin_8
+#define PORT_P25          GPIOC
+#define RCC_Per_P25       RCC_AHB1Periph_GPIOC
+
+#define PIN_NXDN          GPIO_Pin_9
+#define PORT_NXDN         GPIOC
+#define RCC_Per_NXDN      RCC_AHB1Periph_GPIOC
+
+#define PIN_POCSAG        GPIO_Pin_12
+#define PORT_POCSAG       GPIOB
+#define RCC_Per_POCSAG    RCC_AHB1Periph_GPIOB
+
+#define PIN_DSTAR         GPIO_Pin_15
+#define PORT_DSTAR        GPIOB
+#define RCC_Per_DSTAR     RCC_AHB1Periph_GPIOB
+
+#define PIN_DMR           GPIO_Pin_6
+#define PORT_DMR          GPIOC
+#define RCC_Per_DMR       RCC_AHB1Periph_GPIOC
+
+#define PIN_YSF           GPIO_Pin_7
+#define PORT_YSF          GPIOC
+#define RCC_Per_YSF       RCC_AHB1Periph_GPIOC
+
+#define PIN_EXT_CLK       GPIO_Pin_15
+#define SRC_EXT_CLK       GPIO_PinSource15
+#define PORT_EXT_CLK      GPIOA
+
+#define PIN_RX            GPIO_Pin_0
+#define PIN_RX_CH         ADC_Channel_0
+#define PORT_RX           GPIOA
+#define RCC_Per_RX        RCC_AHB1Periph_GPIOA
+
+#define PIN_RSSI          GPIO_Pin_7
+#define PIN_RSSI_CH       ADC_Channel_7
+#define PORT_RSSI         GPIOA
+#define RCC_Per_RSSI      RCC_AHB1Periph_GPIOA
+
+#define PIN_TX            GPIO_Pin_4
+#define PIN_TX_CH         DAC_Channel_1
+
 #elif defined(STM32F4_NUCLEO)
 
 #if defined(STM32F4_NUCLEO_MORPHO_HEADER)
diff --git a/Makefile b/Makefile
index 2c5e005..433dc9b 100644
--- a/Makefile
+++ b/Makefile
@@ -128,6 +128,8 @@ DEFS_NUCLEO_F767=-DUSE_HAL_DRIVER -DSTM32F767xx -DSTM32F7XX -DSTM32F7_NUCLEO -DH
 DEFS_PI_F722=-DUSE_HAL_DRIVER -DSTM32F722xx -DSTM32F7XX -DSTM32F722_PI -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
 # MMDVM-F7M F0DEI board:
 DEFS_F7M=-DUSE_HAL_DRIVER -DSTM32F722xx -DSTM32F7XX -DSTM32F722_F7M -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
+# MMDVM-F7-Hat F0DEI, DB9MAT, DF2ET board:
+DEFS_F7HAT=-DUSE_HAL_DRIVER -DSTM32F722xx -DSTM32F7XX -DSTM32F722_F7HAT -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
 # STM32F4 DVM board:
 DEFS_DVM=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F446xx -DSTM32F4_DVM -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
 
@@ -177,6 +179,12 @@ f7m: CXXFLAGS+=$(CXXFLAGS_F7) $(DEFS_F7M)
 f7m: LDFLAGS+=$(LDFLAGS_F722)
 f7m: release_f7
 
+f7hat: GitVersion.h
+f7hat: CFLAGS+=$(CFLAGS_F7) $(DEFS_F7HAT)
+f7hat: CXXFLAGS+=$(CXXFLAGS_F7) $(DEFS_F7HAT)
+f7hat: LDFLAGS+=$(LDFLAGS_F722)
+f7hat: release_f7
+
 nucleo: GitVersion.h
 nucleo: CFLAGS+=$(CFLAGS_F4) $(DEFS_NUCLEO)
 nucleo: CXXFLAGS+=$(CXXFLAGS_F4) $(DEFS_NUCLEO)
@@ -336,7 +344,8 @@ ifneq ($(wildcard /usr/bin/stm32flash),)
 	/usr/bin/stm32flash -v -w bin/$(BINBIN_F7) -g 0x0 -R -c /dev/ttyAMA0
 endif
 
-deploy-f7m: deploy-pi-f7
+deploy-f7m:   deploy-pi-f7
+deploy-f7hat: deploy-pi-f7
 
 # Export the current git version if the index file exists, else 000...
 GitVersion.h:
diff --git a/SerialArduino.cpp b/SerialArduino.cpp
index 7240a41..db49759 100644
--- a/SerialArduino.cpp
+++ b/SerialArduino.cpp
@@ -21,7 +21,10 @@
 
 #include "SerialPort.h"
 
-#if defined(__SAM3X8E__) || defined(__MK20DX256__) || defined(__MK64FX512__) || defined(__MK66FX1M0__)
+#if defined(VK6MST_TEENSY_PI3_SHIELD_I2C)
+//it will load I2CTeensy.cpp
+
+#elif defined(__SAM3X8E__) || defined(__MK20DX256__) || defined(__MK64FX512__) || defined(__MK66FX1M0__)
 
 void CSerialPort::beginInt(uint8_t n, int speed)
 {
diff --git a/SerialSTM.cpp b/SerialSTM.cpp
index 9eeb53e..f6d26f8 100644
--- a/SerialSTM.cpp
+++ b/SerialSTM.cpp
@@ -50,7 +50,7 @@ extern "C" {
 }
 
 /* ************* USART1 ***************** */
-#if defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_F7M) || defined(STM32F722_PI) || defined(STM32F4_DVM) || (defined(STM32F4_NUCLEO) && defined(STM32F4_NUCLEO_ARDUINO_HEADER))
+#if defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_F7M) || defined(STM32F722_PI) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM) || (defined(STM32F4_NUCLEO) && defined(STM32F4_NUCLEO_ARDUINO_HEADER))
 
 volatile uint8_t  TXSerialfifo1[TX_SERIAL_FIFO_SIZE];
 volatile uint8_t  RXSerialfifo1[RX_SERIAL_FIFO_SIZE];
@@ -841,7 +841,7 @@ void CSerialPort::beginInt(uint8_t n, int speed)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          InitUSART3(speed);
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM)
          InitUSART1(speed);
          #elif defined(STM32F4_NUCLEO)
          InitUSART2(speed);
@@ -865,7 +865,7 @@ int CSerialPort::availableInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return AvailUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM)
          return AvailUSART1();
          #elif defined(STM32F4_NUCLEO)
          return AvailUSART2();
@@ -887,7 +887,7 @@ int CSerialPort::availableForWriteInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return AvailForWriteUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM)
          return AvailForWriteUSART1();
          #elif defined(STM32F4_NUCLEO)
          return AvailForWriteUSART2();
@@ -909,7 +909,7 @@ uint8_t CSerialPort::readInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return ReadUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM)
          return ReadUSART1();
          #elif defined(STM32F4_NUCLEO)
          return ReadUSART2();
@@ -933,7 +933,7 @@ void CSerialPort::writeInt(uint8_t n, const uint8_t* data, uint16_t length, bool
          WriteUSART3(data, length);
          if (flush)
             TXSerialFlush3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_F7HAT) || defined(STM32F4_DVM)
          WriteUSART1(data, length);
          if (flush)
             TXSerialFlush1();