Handle turntable 180 degree reverse

My PR DCC-EX/EX-Turntable#111 gives a much IMO need for a 180 degree reverse on the turntable.

This will ensure we get correct messaging and commands.

Author: mwinters-stuff

IODevice.h

@@ -425,6 +425,7 @@ class EXTurntable : public IODevice {
     LED_Off = 7,          // Turn LED off
     Acc_On = 8,           // Turn accessory pin on
     Acc_Off = 9,          // Turn accessory pin off
+    Reverse = 18,         // Reverse turntable 180 degrees
   };
 
 private:

IO_EXTurntable.cpp

@@ -72,7 +72,7 @@ void EXTurntable::_loop(unsigned long currentMicros) {
   I2CManager.read(_I2CAddress, readBuffer, 1);
   _stepperStatus = readBuffer[0];
   if (_stepperStatus != _previousStatus && _stepperStatus == 0) { // Broadcast when a rotation finishes
-    if ( _currentActivity < 4) {
+    if ( _currentActivity < ActivityNumber::LED_On || _currentActivity == ActivityNumber::Reverse) {
       _broadcastStatus(_firstVpin, _stepperStatus, _currentActivity);
     }
     _previousStatus = _stepperStatus;
@@ -96,7 +96,7 @@ int EXTurntable::_read(VPIN vpin) {
 void EXTurntable::_broadcastStatus (VPIN vpin, uint8_t status, uint8_t activity) {
   Turntable *tto = Turntable::getByVpin(vpin);
   if (tto) {
-    if (activity < 4) {
+    if (activity < ActivityNumber::LED_On || activity == ActivityNumber::Reverse) {
       tto->setMoving(status);
       CommandDistributor::broadcastTurntable(tto->getId(), tto->getPosition(), status);
     }
@@ -129,9 +129,9 @@ void EXTurntable::_writeAnalogue(VPIN vpin, int value, uint8_t activity, uint16_
   DIAG(F("I2CManager write I2C Address:%d stepsMSB:%d stepsLSB:%d activity:%d"),
     _I2CAddress.toString(), stepsMSB, stepsLSB, activity);
 #else
-  (void)duration;
+   (void)duration;
 #endif
-  if (activity < 4) _stepperStatus = 1;     // Tell the device driver Turntable-EX is busy
+  if (activity < ActivityNumber::LED_On || activity == ActivityNumber::Reverse) _stepperStatus = 1;     // Tell the device driver Turntable-EX is busy
   _previousStatus = _stepperStatus;
   _currentActivity = activity;
   _broadcastStatus(vpin, _stepperStatus, activity); // Broadcast when the rotation starts

Turntables.cpp

@@ -142,6 +142,11 @@ bool Turntable::setPosition(uint16_t id, uint8_t position, uint8_t activity) {
   Turntable *tto = Turntable::get(id);
   if (!tto) return false;
   if (tto->isMoving()) return false;
+  
+  if(activity == EXTurntable::ActivityNumber::Reverse){
+    // A 180-degree turn keeps the same logical track position.
+    position = tto->getPosition();
+  }
   bool ok = tto->setPositionInternal(position, activity);
 
   if (ok) {
@@ -152,7 +157,7 @@ bool Turntable::setPosition(uint16_t id, uint8_t position, uint8_t activity) {
     // Trigger EXRAIL rotateEvent for both types here if changed
 #if defined(EXRAIL_ACTIVE)
     bool rotated = false;
-    if (position != tto->_previousPosition) rotated = true;
+    if (position != tto->_previousPosition || activity == EXTurntable::ActivityNumber::Reverse) rotated = true;
     RMFT2::rotateEvent(id, rotated);
 #endif
   }
@@ -204,12 +209,19 @@ using DevState = IODevice::DeviceStateEnum;
   bool EXTTTurntable::setPositionInternal(uint8_t position, uint8_t activity) {
 #ifndef IO_NO_HAL
     int16_t value;
-    if (position == 0) {
-      value = 0;  // Position 0 is just to send activities
-    } else {
-      if (activity > 1) return false; // If sending a position update, only phase changes valid (0|1)
+    if(activity == EXTurntable::ActivityNumber::Reverse) {
+      // Keep logical position unchanged while issuing the 180 action.
+      position = _turntableData.position;
       value = getPositionValue(position); // Get position value from position list
+    }else {
+      if (position == 0) {
+        value = 0;  // Position 0 is just to send activities
+      } else {
+        if (activity > EXTurntable::ActivityNumber::Turn_PInvert) return false; // If sending a position update, only phase changes valid (0|1)
+        value = getPositionValue(position); // Get position value from position list
+      }
     }
+
     if (position > 0 && !value) return false; // Return false if it's not a valid position
     // Set position via device driver
     _previousPosition = _turntableData.position;