Fix settable flight mode channel

src/AutoPilotPlugins/APM/APMFlightModesComponent.qml

@@ -39,6 +39,9 @@ QGCView {
     property bool   _channel7OptionsAvailable:  controller.parameterExists(-1, "CH7_OPT")   // Not available in all firmware types
     property bool   _channel9OptionsAvailable:  controller.parameterExists(-1, "CH9_OPT")   // Not available in all firmware types
     property int    _channelOptionCount:         _channel7OptionsAvailable ? (_channel9OptionsAvailable ? 6 : 2) : 0
+    property Fact   _nullFact
+    property bool   _fltmodeChExists:           controller.parameterExists(-1, "FLTMODE_CH")
+    property Fact   _fltmodeCh:                 _fltmodeChExists ? controller.getParameterFact(-1, "FLTMODE_CH") : _nullFact
 
     QGCPalette { id: qgcPal; colorGroupEnabled: panel.enabled }
 
@@ -59,7 +62,7 @@ QGCView {
 
             QGCLabel {
                 id:             flightModeLabel
-                text:           "Channel 5 Flight Mode Settings"
+                text:           "Flight Mode Settings" + (_fltmodeChExists ? "" : " (Channel 5)")
                 font.weight:    Font.DemiBold
             }
 
@@ -75,10 +78,28 @@ QGCView {
                     id:                 flightModeColumn
                     anchors.margins:    ScreenTools.defaultFontPixelWidth
                     anchors.left:       parent.left
-                    //  anchors.right:      parent.right
                     anchors.top:        parent.top
                     spacing:            ScreenTools.defaultFontPixelHeight
 
+                    Row {
+                        spacing:    _margins
+                        visible:    _fltmodeChExists
+
+                        QGCLabel {
+                            id:                 modeChannelLabel
+                            anchors.baseline:   modeChannelCombo.baseline
+                            text:               "Flight mode channel:"
+                        }
+
+                        QGCComboBox {
+                            id:             modeChannelCombo
+                            width:          ScreenTools.defaultFontPixelWidth * 15
+                            model:          [ "Not assigned", "Channel 1", "Channel 2","Channel 3","Channel 4","Channel 5","Channel 6","Channel 7","Channel 8" ]
+                            currentIndex:   _fltmodeCh.value
+                            onActivated:    _fltmodeCh.value = index
+                        }
+                    }
+
                     Repeater {
                         model:  6
 

src/AutoPilotPlugins/APM/APMFlightModesComponentController.cc

@@ -32,8 +32,6 @@ APMFlightModesComponentController::APMFlightModesComponentController(void)
     : _activeFlightMode(0)
     , _channelCount(Vehicle::cMaxRcChannels)
     , _fixedWing(_vehicle->vehicleType() == MAV_TYPE_FIXED_WING)
-    , _flightModeChannel(5)
-
 {
     QStringList usedParams;
     usedParams << QStringLiteral("FLTMODE1") << QStringLiteral("FLTMODE2") << QStringLiteral("FLTMODE3")
@@ -42,10 +40,6 @@ APMFlightModesComponentController::APMFlightModesComponentController(void)
         return;
     }
 
-    if (parameterExists(FactSystem::defaultComponentId, QStringLiteral("FLTMODE_CH"))) {
-        _flightModeChannel = getParameterFact(FactSystem::defaultComponentId, QStringLiteral("FLTMODE_CH"))->rawValue().toInt();
-    }
-
     _rgChannelOptionEnabled << QVariant(false) << QVariant(false) << QVariant(false) << QVariant(false) << QVariant(false) << QVariant(false);
     
     connect(_vehicle, &Vehicle::rcChannelsChanged, this, &APMFlightModesComponentController::_rcChannelsChanged);
@@ -54,12 +48,18 @@ APMFlightModesComponentController::APMFlightModesComponentController(void)
 /// Connected to Vehicle::rcChannelsChanged signal
 void APMFlightModesComponentController::_rcChannelsChanged(int channelCount, int pwmValues[Vehicle::cMaxRcChannels])
 {
-    if (_flightModeChannel > channelCount) {
+    int flightModeChannel = 4;
+
+    if (parameterExists(FactSystem::defaultComponentId, QStringLiteral("FLTMODE_CH"))) {
+        flightModeChannel = getParameterFact(FactSystem::defaultComponentId, QStringLiteral("FLTMODE_CH"))->rawValue().toInt() - 1;
+    }
+
+    if (flightModeChannel >= channelCount) {
         return;
     }
 
     _activeFlightMode = 0;
-    int channelValue = pwmValues[_flightModeChannel - 1];
+    int channelValue = pwmValues[flightModeChannel];
     if (channelValue != -1) {
         bool found = false;
         int rgThreshold[] = { 1230, 1360, 1490, 1620, 1749 };

src/AutoPilotPlugins/APM/APMFlightModesComponentController.h

@@ -62,7 +62,6 @@ private:
     int             _channelCount;
     QVariantList    _rgChannelOptionEnabled;
     bool            _fixedWing;
-    int             _flightModeChannel;
 };
 
 #endif