Plane: ensure throttle reverse is obeyed in all states

need to use radio_max for failsafe if reversed

ArduPlane/Attitude.cpp

@@ -737,6 +737,14 @@ void Plane::set_servos_idle(void)
     channel_throttle->output_trim();
 }
 
+/*
+  return minimum throttle, taking account of throttle reversal
+ */
+uint16_t Plane::throttle_min(void) const
+{
+    return channel_throttle->get_reverse() ? channel_throttle->radio_max : channel_throttle->radio_min;
+};
+
 
 /*****************************************
 * Set the flight control servos based on the current calculated values
@@ -1004,7 +1012,7 @@ void Plane::set_servos(void)
 
         case AP_Arming::YES_MIN_PWM:
         default:
-            channel_throttle->radio_out = channel_throttle->radio_min;
+            channel_throttle->radio_out = throttle_min();
             break;
         }
     }

ArduPlane/Plane.h

@@ -956,7 +956,8 @@ private:
     uint32_t micros() const;
     void init_capabilities(void);
     void dataflash_periodic(void);
-
+    uint16_t throttle_min(void) const;
+    
 public:
     void mavlink_delay_cb();
     void failsafe_check(void);

ArduPlane/px4_mixer.cpp

@@ -259,7 +259,7 @@ bool Plane::setup_failsafe_mixing(void)
     if (old_state == AP_HAL::Util::SAFETY_ARMED) {
         // make sure the throttle has a non-zero failsafe value before we
         // disable safety. This prevents sending zero PWM during switch over
-        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), channel_throttle->radio_min);
+        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), throttle_min());
     }
 
     // we need to force safety on to allow us to load a mixer. We call

ArduPlane/radio.cpp

@@ -28,7 +28,7 @@ void Plane::set_control_channels(void)
     channel_throttle->set_range(0, 100);
 
     if (!arming.is_armed() && arming.arming_required() == AP_Arming::YES_MIN_PWM) {
-        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), channel_throttle->radio_min);
+        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), throttle_min());
     }
 
     // setup correct scaling for ESCs like the UAVCAN PX4ESC which
@@ -63,7 +63,7 @@ void Plane::init_rc_out()
       configuration error where the user sets CH3_TRIM incorrectly and
       the motor may start on power up
      */
-    channel_throttle->radio_trim = channel_throttle->get_reverse() ? channel_throttle->radio_max : channel_throttle->radio_min;
+    channel_throttle->radio_trim = throttle_min();
     
     if (arming.arming_required() != AP_Arming::YES_ZERO_PWM) {
         channel_throttle->enable_out();
@@ -80,7 +80,7 @@ void Plane::init_rc_out()
     // setup PX4 to output the min throttle when safety off if arming
     // is setup for min on disarm
     if (arming.arming_required() == AP_Arming::YES_MIN_PWM) {
-        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), channel_throttle->radio_min);
+        hal.rcout->set_safety_pwm(1UL<<(rcmap.throttle()-1), throttle_min());
     }
 }