diff --git a/EX-IOExpanderPinMaps.h b/EX-IOExpanderPinMaps.h
new file mode 100644
index 0000000..b09dca3
--- /dev/null
+++ b/EX-IOExpanderPinMaps.h
@@ -0,0 +1,38 @@
+/*
+ *  © 2022 Peter Cole
+ *
+ *  This file is part of EX-CommandStation
+ *
+ *  This 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It 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 CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*
+*   This file defines default pin maps for the various architectures supported
+*   by default by EX-IOExpander.
+*   
+*   Custom user defined pinmaps should be defined in myEX-IOExpander.h.
+*
+*   Any modifications to this file will be overwritten by future software updates.
+*/
+
+#define DEFAULT_NANO_DIGITAL_PINMAP new EXIODigitalPinMap(12,2,3,4,5,6,7,8,9,10,11,12,13,A0,A1,A2,A3,A6,A7)
+#define DEFAULT_NANO_ANALOGUE_PINMAP new EXIOAnaloguePinMap(6,A0,A1,A2,A3,A6,A7)
+
+#define DEFAULT_UNO F("DEFAULT_UNO"), \
+  new EXIODigitalPinMap(12,2,3,4,5,6,7,8,9,10,11,12,13,A0,A1,A2,A3,A6,A7) \
+  new EXIOAnaloguePinMap(4,A0,A1,A2,A3)
+
+#define DEFAULT_MEGA F("DEFAULT_MEGA"), \
+  new EXIODigitalPinMap(12,2,3,4,5,6,7,8,9,10,11,12,13,A0,A1,A2,A3,A6,A7) \
+  new EXIOAnaloguePinMap(4,A0,A1,A2,A3)
\ No newline at end of file
diff --git a/IO_EXIOExpander.h b/IO_EXIOExpander.h
index c979176..052ad72 100644
--- a/IO_EXIOExpander.h
+++ b/IO_EXIOExpander.h
@@ -28,31 +28,65 @@
 
 #include "IO_GPIOBase.h"
 #include "FSH.h"
+#include "EX-IOExpanderPinMaps.h"
 
-#if __has_include ("myPinMap.h")
-  #include "myPinMap.h"
-#else
-  #warning myPinMap.h not found. Using defaults from myPinMap.example.h
-  #include "myPinMap.example.h"
+// Include user defined pin maps in myEX-IOExpander if defined
+#if __has_include ("myEX-IOExpander.h")
+  #include "myEX-IOExpander.h"
 #endif
 
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+/*
+ * EXIODigitalPinMap class for EX-IOExpander.
+ */
+class EXIODigitalPinMap {
+  public:
+    EXIODigitalPinMap(uint8_t numDigitalPins, uint8_t...);
+    EXIODigitalPinMap() = default;
+
+  private:
+    EXIODigitalPinMap(uint8_t numDigitalPins, ...) {
+      _numDigitalPins = numDigitalPins;
+      uint8_t _digitalPinMap[_numDigitalPins];
+      va_list _pinList;
+      va_start(_pinList, _numDigitalPins);
+      for (uint8_t pin = 0; pin < _numDigitalPins; pin++) {
+        _digitalPinMap[pin] = va_arg(_pinList, int);
+      }
+      va_end(_pinList);
+    }
+
+    uint8_t _numDigitalPins;
+};
+
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+/*
+ * EXIOAnaloguePinMap class for EX-IOExpander.
+ */
+class EXIOAnaloguePinMap {
+  public:
+    EXIOAnaloguePinMap(uint8_t numAnaloguePins, ...);
+    EXIOAnaloguePinMap() = default;
+};
+
 /////////////////////////////////////////////////////////////////////////////////////////////////////
 /*
  * IODevice subclass for EX-IOExpander.
  */
- 
 class EXIOExpander : public IODevice {
 public:
-  static void create(VPIN vpin, int nPins, uint8_t i2cAddress) {
-    if (checkNoOverlap(vpin, nPins, i2cAddress)) new EXIOExpander(vpin, nPins, i2cAddress);
+  static void create(VPIN vpin, int nPins, uint8_t i2cAddress, EXIODigitalPinMap digitalPinMap, EXIOAnaloguePinMap analoguePinMap) {
+    if (checkNoOverlap(vpin, nPins, i2cAddress)) new EXIOExpander(vpin, nPins, i2cAddress, digitalPinMap, analoguePinMap);
   }
 
 private:  
   // Constructor
-  EXIOExpander(VPIN firstVpin, int nPins, uint8_t i2cAddress) {
+  EXIOExpander(VPIN firstVpin, int nPins, uint8_t i2cAddress, EXIODigitalPinMap digitalPinMap, EXIOAnaloguePinMap analoguePinMap) {
     _firstVpin = firstVpin;
     _nPins = nPins;
     _i2cAddress = i2cAddress;
+    _digitalPinMap = digitalPinMap;
+    _analoguePinMap = analoguePinMap;
     addDevice(this);
   }
 
@@ -74,6 +108,8 @@ private:
   }
 
   uint8_t _i2cAddress;
+  EXIODigitalPinMap _digitalPinMap;
+  EXIOAnaloguePinMap _analoguePinMap;
 };
 
 #endif
\ No newline at end of file
diff --git a/myEX-IOExpander.example.h b/myEX-IOExpander.example.h
new file mode 100644
index 0000000..3402c92
--- /dev/null
+++ b/myEX-IOExpander.example.h
@@ -0,0 +1,23 @@
+/*
+ *  © 2022 Peter Cole. All rights reserved.
+ *
+ *  This is the example configuration file for a custom EX-IOExpander pin map file.
+ * 
+ *  It is highly recommended to copy this to "myEX-IOExpander.h" and modify to suit your specific
+ *  requirements.
+ * 
+ *  If you are simply using a default definition for a defined microcontroller, then you don't
+ *  need to use this file, and instead can use one of the existing definitions.
+ *  
+ *  Refer to https://dcc-ex.com for the full documentation.
+ * 
+ *  NOTE: Modifications to this file will be overwritten by future software updates.
+ */
+#ifndef MYEX_IOEXPANDER_H
+#define MYEX_IOEXPANDER_H
+
+#define MY_CUSTOM_NANO F("MY_NANO_PINMAP"), \
+  new EXIODigitalPinMap(12,2,3,4,5,6,7,8,9,10,11,12,13) \
+  new EXIOAnaloguePinMap(4,A0,A1,A2,A3)
+
+#endif
\ No newline at end of file
diff --git a/myPinMap.example.h b/myPinMap.example.h
deleted file mode 100644
index 3afebc1..0000000
--- a/myPinMap.example.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/*
- *  © 2022 Peter Cole. All rights reserved.
- *
- *  This is the example configuration file for the EX-IOExpander pin map file.
- * 
- *  It is highly recommended to copy this to "myPinMap.h" and modify to suit your specific
- *  requirements.
- * 
- *  NOTE: Modifications to this file will be overwritten by future software updates.
- */
-#ifndef MYPINMAP_H
-#define MYPINMAP_H
-
-/////////////////////////////////////////////////////////////////////////////////////
-//  Define the number of I/O pins to be configured on the EX-IOExpander device
-// 
-#define NUMBER_OF_DIGITAL_PINS 12
-#define NUMBER_OF_ANALOGUE_PINS 4
-
-/////////////////////////////////////////////////////////////////////////////////////
-//  Define the pin map
-// 
-//  You must define the correct number of pins as per NUMBER_OF_PINS above
-//
-static uint8_t digitalPinMap[NUMBER_OF_DIGITAL_PINS] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13};
-static uint8_t analoguePinMap[NUMBER_OF_ANALOGUE_PINS] = {A0, A1, A2, A3};
-
-#endif
\ No newline at end of file