ArduCopter: add Airspeed support

ArduCopter/AP_Arming.cpp

@@ -62,6 +62,9 @@ bool AP_Arming_Copter::run_pre_arm_checks(bool display_failure)
         & gcs_failsafe_check(display_failure)
         & winch_checks(display_failure)
         & alt_checks(display_failure)
+#if AP_AIRSPEED_ENABLED
+        & AP_Arming::airspeed_checks(display_failure)
+#endif
         & AP_Arming::pre_arm_checks(display_failure);
 }
 

ArduCopter/GCS_Mavlink.cpp

@@ -195,6 +195,16 @@ void GCS_MAVLINK_Copter::send_nav_controller_output() const
 
 float GCS_MAVLINK_Copter::vfr_hud_airspeed() const
 {
+#if AP_AIRSPEED_ENABLED
+    // airspeed sensors are best. While the AHRS airspeed_estimate
+    // will use an airspeed sensor, that value is constrained by the
+    // ground speed. When reporting we should send the true airspeed
+    // value if possible:
+    if (copter.airspeed.enabled() && copter.airspeed.healthy()) {
+        return copter.airspeed.get_airspeed();
+    }
+#endif
+    
     Vector3f airspeed_vec_bf;
     if (AP::ahrs().airspeed_vector_true(airspeed_vec_bf)) {
         // we are running the EKF3 wind estimation code which can give

ArduCopter/system.cpp

@@ -111,6 +111,10 @@ void Copter::init_ardupilot()
     AP::compass().set_log_bit(MASK_LOG_COMPASS);
     AP::compass().init();
 
+#if AP_AIRSPEED_ENABLED
+    airspeed.set_log_bit(MASK_LOG_IMU);
+#endif
+
 #if AC_OAPATHPLANNER_ENABLED == ENABLED
     g2.oa.init();
 #endif