From a458f1bf5f402831178d35c00e07b55b346adfa7 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Tue, 22 Jul 2014 18:07:48 +1000
Subject: [PATCH] AP_Baro: minor improvements to Baro HIL code health check

---
 libraries/AP_Baro/AP_Baro.cpp     |  6 ++++--
 libraries/AP_Baro/AP_Baro_HIL.cpp | 13 ++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/libraries/AP_Baro/AP_Baro.cpp b/libraries/AP_Baro/AP_Baro.cpp
index 3f1f3dc69a..e4f40da04f 100644
--- a/libraries/AP_Baro/AP_Baro.cpp
+++ b/libraries/AP_Baro/AP_Baro.cpp
@@ -125,7 +125,8 @@ void AP_Baro::calibrate()
 */
 void AP_Baro::update_calibration()
 {
-    _ground_pressure.set(get_pressure());
+    float pressure = get_pressure();
+    _ground_pressure.set(pressure);
     _ground_temperature.set(get_temperature());
 }
 
@@ -166,7 +167,8 @@ float AP_Baro::get_altitude(void)
         return _altitude + _alt_offset;
     }
 
-    _altitude = get_altitude_difference(_ground_pressure, get_pressure());
+    float pressure = get_pressure();
+    _altitude = get_altitude_difference(_ground_pressure, pressure);
 
     _last_altitude_t = _last_update;
 
diff --git a/libraries/AP_Baro/AP_Baro_HIL.cpp b/libraries/AP_Baro/AP_Baro_HIL.cpp
index a33b3c809e..835e8b9509 100644
--- a/libraries/AP_Baro/AP_Baro_HIL.cpp
+++ b/libraries/AP_Baro/AP_Baro_HIL.cpp
@@ -9,6 +9,7 @@ extern const AP_HAL::HAL& hal;
 // Public Methods //////////////////////////////////////////////////////////////
 bool AP_Baro_HIL::init()
 {
+    healthy = false;
     return true;
 }
 
@@ -35,11 +36,13 @@ uint8_t AP_Baro_HIL::read()
 
 void AP_Baro_HIL::setHIL(float pressure, float temperature)
 {
-    _count = 1;
-    _pressure_sum = pressure;
-    _temperature_sum = temperature;
-    _last_update = hal.scheduler->millis();
-    healthy = true;
+    if (pressure > 0) {
+        _count = 1;
+        _pressure_sum = pressure;
+        _temperature_sum = temperature;
+        _last_update = hal.scheduler->millis();
+        healthy = true;
+    }
 }