From 88a230e897ef8d416a37878d0f7637bd968c4a4e Mon Sep 17 00:00:00 2001
From: Randy Mackay <rmackay9@yahoo.com>
Date: Mon, 27 Aug 2018 16:03:43 +0900
Subject: [PATCH] Rover: DPTH message only written if range finder last read
 time changed

---
 APMrover2/Log.cpp | 7 +++++++
 APMrover2/Rover.h | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/APMrover2/Log.cpp b/APMrover2/Log.cpp
index ebed896252..47f44644e4 100644
--- a/APMrover2/Log.cpp
+++ b/APMrover2/Log.cpp
@@ -60,6 +60,13 @@ void Rover::Log_Write_Depth()
         return;
     }
 
+    // check if new sensor reading has arrived
+    uint32_t reading_ms = rangefinder.last_reading_ms(ROTATION_PITCH_270);
+    if (reading_ms == rangefinder_last_reading_ms) {
+        return;
+    }
+    rangefinder_last_reading_ms = reading_ms;
+
     DataFlash.Log_Write("DPTH", "TimeUS,Lat,Lng,Depth",
                         "sDUm", "FGG0", "QLLf",
                         AP_HAL::micros64(),
diff --git a/APMrover2/Rover.h b/APMrover2/Rover.h
index d7fe194102..5fd48f2797 100644
--- a/APMrover2/Rover.h
+++ b/APMrover2/Rover.h
@@ -280,6 +280,9 @@ private:
         uint32_t detected_time_ms;
     } obstacle;
 
+    // range finder last update (used for DPTH logging)
+    uint32_t rangefinder_last_reading_ms;
+
     // Ground speed
     // The amount current ground speed is below min ground speed.  meters per second
     float ground_speed;