Warn on reversed throttle (#3655)

src/AutoPilotPlugins/Common/RadioComponent.qml

@@ -64,6 +64,7 @@ QGCView {
 
         onChannelCountChanged:              updateChannelCount()
         onFunctionMappingChangedAPMReboot:  showMessage(qsTr("Reboot required"), qsTr("Your stick mappings have changed, you must reboot the vehicle for correct operation."), StandardButton.Ok)
+        onThrottleReversedCalFailure:       showMessage(qsTr("Throttle channel reversed"), qsTr("Calibration failed. The throttle channel on your transmitter is reversed. You must correct this on your transmitter in order to complete calibration."), StandardButton.Ok)
     }
 
     onCompleted: {

src/AutoPilotPlugins/Common/RadioComponentController.cc

@@ -325,7 +325,7 @@ void RadioComponentController::_saveAllTrims(void)
     // trims reset to correct values.
     
     for (int i=0; i<_chanCount; i++) {
-        qCDebug(RadioComponentControllerLog) << "_saveAllTrims trim" << _rcRawValue[i];
+        qCDebug(RadioComponentControllerLog) << "_saveAllTrims channel trim" << i<< _rcRawValue[i];
         _rgChannelInfo[i].rcTrim = _rcRawValue[i];
     }
     _advanceState();
@@ -752,6 +752,11 @@ void RadioComponentController::_writeCalibration(void)
         _uas->stopCalibration();
     }
 
+    if (!_px4Vehicle() && _rgChannelInfo[_rgFunctionChannelMapping[rcCalFunctionThrottle]].reversed) {
+        // A reversed throttle could lead to dangerous power up issues if the firmware doesn't handle it absolutely correctly in all places.
+        // So in this case fail the calibration for anything other than PX4 which is known to be able to handle this correctly.
+        emit throttleReversedCalFailure();
+    } else {
         _validateCalibration();
 
         QString minTpl("RC%1_MIN");
@@ -821,6 +826,7 @@ void RadioComponentController::_writeCalibration(void)
                 }
             }
         }
+    }
 
     if (_px4Vehicle()) {
         // If the RC_CHAN_COUNT parameter is available write the channel count

src/AutoPilotPlugins/Common/RadioComponentController.h

@@ -124,12 +124,15 @@ signals:
     void imageHelpChanged(QString source);
     void transmitterModeChanged(int mode);
     
-    // @brief Signalled when in unit test mode and a message box should be displayed by the next button
+    /// Signalled when in unit test mode and a message box should be displayed by the next button
     void nextButtonMessageBoxDisplayed(void);
 
-    // Signaled to QML to indicator reboot is required
+    /// Signalled to QML to indicate reboot is required
     void functionMappingChangedAPMReboot(void);
 
+    /// Signalled to Qml to indicate cal failure due to reversed throttle
+    void throttleReversedCalFailure(void);
+
 private slots:
     void _rcChannelsChanged(int channelCount, int pwmValues[Vehicle::cMaxRcChannels]);