AP_NavEKF: minor comment fix

No functional change

libraries/AP_NavEKF/AP_NavEKF.cpp

@@ -4516,8 +4516,9 @@ Quaternion NavEKF::calcQuatAndFieldStates(float roll, float pitch)
             // store the yaw change so that it can be retrieved externally for use by the control loops to prevent yaw disturbances following a reset
             Vector3f tempEuler;
             state.quat.to_euler(tempEuler.x, tempEuler.y, tempEuler.z);
+            // this check ensures we accumulate the resets that occur within a single iteration of the EKF
             if (imuSampleTime_ms != lastYawReset_ms) {
-                yawResetAngle = 0;
+                yawResetAngle = 0.0f;
             }
             yawResetAngle += wrap_PI(yaw - tempEuler.z);
             lastYawReset_ms = imuSampleTime_ms;
@@ -4877,9 +4878,9 @@ return the filter fault status as a bitmasked integer
  1 = velocities are NaN
  2 = badly conditioned X magnetometer fusion
  3 = badly conditioned Y magnetometer fusion
- 5 = badly conditioned Z magnetometer fusion
- 6 = badly conditioned airspeed fusion
- 7 = badly conditioned synthetic sideslip fusion
+ 4 = badly conditioned Z magnetometer fusion
+ 5 = badly conditioned airspeed fusion
+ 6 = badly conditioned synthetic sideslip fusion
  7 = filter is not initialised
 */
 void  NavEKF::getFilterFaults(uint8_t &faults) const
@@ -5400,7 +5401,7 @@ void NavEKF::alignMagStateDeclination()
 }
 
 // return the amount of yaw angle change due to the last yaw angle reset in radians
-// returns the system time at which the yaw angle was reset
+// returns the time of the last yaw angle reset or 0 if no reset has ever occurred
 uint32_t NavEKF::getLastYawResetAngle(float &yawAng)
 {
     yawAng = yawResetAngle;

libraries/AP_NavEKF/AP_NavEKF.h

@@ -225,9 +225,9 @@ public:
      1 = velocities are NaN
      2 = badly conditioned X magnetometer fusion
      3 = badly conditioned Y magnetometer fusion
-     5 = badly conditioned Z magnetometer fusion
-     6 = badly conditioned airspeed fusion
-     7 = badly conditioned synthetic sideslip fusion
+     4 = badly conditioned Z magnetometer fusion
+     5 = badly conditioned airspeed fusion
+     6 = badly conditioned synthetic sideslip fusion
      7 = filter is not initialised
     */
     void  getFilterFaults(uint8_t &faults) const;
@@ -238,10 +238,10 @@ public:
      1 = velocity measurement timeout
      2 = height measurement timeout
      3 = magnetometer measurement timeout
+     4 = true airspeed measurement timeout
      5 = unassigned
      6 = unassigned
      7 = unassigned
-     7 = unassigned
     */
     void  getFilterTimeouts(uint8_t &timeouts) const;
 
@@ -259,7 +259,7 @@ public:
     bool getHeightControlLimit(float &height) const;
 
     // return the amount of yaw angle change due to the last yaw angle reset in radians
-    // returns the system time at which the yaw angle was reset
+    // returns the time of the last yaw angle reset or 0 if no reset has ever occurred
     uint32_t getLastYawResetAngle(float &yawAng);
 
     // report any reason for why the backend is refusing to initialise