diff --git a/IO_EXIOExpander.h b/IO_EXIOExpander.h
index 724ea42..f284bc1 100644
--- a/IO_EXIOExpander.h
+++ b/IO_EXIOExpander.h
@@ -1,5 +1,5 @@
 /*
- *  © 2021, Peter Cole. All rights reserved.
+ *  © 2022, Peter Cole. All rights reserved.
  *
  *  This file is part of EX-CommandStation
  *
@@ -26,19 +26,14 @@
 * (Note the device driver is included by default)
 *
 * void halSetup() {
-*   // EXIOExpander::create(vpin, num_vpins, i2c_address, digitalPinCount, analoguePinCount);
-*   EXIOExpander::create(800, 18, 0x65, 12, 8);
+*   // EXIOExpander::create(vpin, num_vpins, i2c_address);
+*   EXIOExpander::create(800, 18, 0x65);
 * }
 * 
-* Note when defining the number of digital and analogue pins, there is no way to sanity check
-* this from the device driver, and it is up to the user to define the correct values here.
-*
-* All pins available on the EX-IOExpander device must be accounted for.
-* 
-* Vpins are allocated to digital pins first, and then analogue pins, so digital pins will
-* populate the first part of the specified vpin range, with the analogue pins populating the
-* last part of the vpin range.
-* Eg. for a default Nano, 800 - 811 are digital (D2 - D13), 812 to 817 are analogue (A0 - A3, A6/A7).
+* All pins on an EX-IOExpander device are allocated according to the pin map for the specific
+* device in use. There is no way for the device driver to sanity check pins are used for the
+* correct purpose, however the EX-IOExpander device's pin map will prevent pins being used
+* incorrectly (eg. A6/7 on Nano cannot be used for digital input/output).
 */
 
 #ifndef IO_EX_IOEXPANDER_H
@@ -76,12 +71,15 @@ private:
       _command2Buffer[0] = EXIOINIT;
       _command2Buffer[1] = _nPins;
       // Send config, if EXIOINITA returned, we're good, setup analogue input buffer, otherwise go offline
-      I2CManager.read(_i2cAddress, _receive2Buffer, 2, _command2Buffer, 2);
-      if (_receive2Buffer[0] == EXIOINITA) {
-        _numAnaloguePins = _receive2Buffer[1];
+      I2CManager.read(_i2cAddress, _receive3Buffer, 3, _command2Buffer, 2);
+      if (_receive3Buffer[0] == EXIOINITA) {
+        _numAnaloguePins = _receive3Buffer[1];
+        _numPWMPins = _receive3Buffer[2];
         _analoguePinBytes = _numAnaloguePins * 2;
         _analogueInputStates = (byte*) calloc(_analoguePinBytes, 1);
         _analoguePinMap = (uint8_t*) calloc(_numAnaloguePins, 1);
+        _servoData = (struct ServoData*) calloc(_numPWMPins, 14);
+
       } else {
         DIAG(F("ERROR configuring EX-IOExpander device, I2C:x%x"), _i2cAddress);
         _deviceState = DEVSTATE_FAILED;
@@ -109,15 +107,24 @@ private:
 
   // Digital input pin configuration, used to enable on EX-IOExpander device and set pullups if in use
   bool _configure(VPIN vpin, ConfigTypeEnum configType, int paramCount, int params[]) override {
-    if (configType != CONFIGURE_INPUT) return false;
     if (paramCount != 1) return false;
-    bool pullup = params[0];
     int pin = vpin - _firstVpin;
-    _digitalOutBuffer[0] = EXIODPUP;
-    _digitalOutBuffer[1] = pin;
-    _digitalOutBuffer[2] = pullup;
-    I2CManager.write(_i2cAddress, _digitalOutBuffer, 3);
-    return true;
+    if (configType == CONFIGURE_INPUT) {
+      bool pullup = params[0];
+      _digitalOutBuffer[0] = EXIODPUP;
+      _digitalOutBuffer[1] = pin;
+      _digitalOutBuffer[2] = pullup;
+      I2CManager.write(_i2cAddress, _digitalOutBuffer, 3);
+      return true;
+    } else if (configType == CONFIGURE_SERVO) {
+      DIAG(F("Configure servo at pin %d"), (int)pin);
+      for (int i = 0; i < paramCount; i++) {
+        DIAG(F("Param %d is %x"), (int)i, params[i]);
+      }
+      return true;
+    } else {
+      return false;
+    }
   }
 
   // Analogue input pin configuration, used to enable on EX-IOExpander device
@@ -175,7 +182,7 @@ private:
   }
 
   uint8_t _i2cAddress;
-  uint8_t _numAnaloguePins;
+  uint8_t _numAnaloguePins = 0;
   byte _digitalOutBuffer[3];
   uint8_t _versionBuffer[3];
   uint8_t _majorVer = 0;
@@ -187,8 +194,29 @@ private:
   uint8_t _analoguePinBytes = 0;
   byte _command1Buffer[1];
   byte _command2Buffer[2];
-  byte _receive2Buffer[2];
+  byte _receive3Buffer[3];
   uint8_t* _analoguePinMap;
+  uint8_t _numPWMPins = 0;
+
+  struct ServoData {
+    uint16_t activePosition : 12; // Config parameter
+    uint16_t inactivePosition : 12; // Config parameter
+    uint16_t currentPosition : 12;
+    uint16_t fromPosition : 12;
+    uint16_t toPosition : 12; 
+    uint8_t profile;  // Config parameter
+    uint16_t stepNumber; // Index of current step (starting from 0)
+    uint16_t numSteps;  // Number of steps in animation, or 0 if none in progress.
+    uint8_t currentProfile; // profile being used for current animation.
+    uint16_t duration; // time (tenths of a second) for animation to complete.
+  } ServoData; // 14 bytes per element, i.e. per pin in use
+  
+  struct ServoData* _servoData;
+
+  static const uint8_t _catchupSteps = 5; // number of steps to wait before switching servo off
+  static const byte FLASH _bounceProfile[30];
+
+  const unsigned int refreshInterval = 50; // refresh every 50ms
 
   enum {
     EXIOINIT = 0xE0,    // Flag to initialise setup procedure