From 76da561970ea879cb652eedd0124f6855237f442 Mon Sep 17 00:00:00 2001
From: Randy Mackay <rmackay9@yahoo.com>
Date: Tue, 15 Sep 2015 15:58:43 +0900
Subject: [PATCH] Copter: replace vehicle compass consistency check

---
 ArduCopter/config.h   |  5 -----
 ArduCopter/motors.cpp | 14 +-------------
 2 files changed, 1 insertion(+), 18 deletions(-)

diff --git a/ArduCopter/config.h b/ArduCopter/config.h
index 2698df963b..540788089d 100644
--- a/ArduCopter/config.h
+++ b/ArduCopter/config.h
@@ -307,11 +307,6 @@
  #endif
 #endif
 
-// arming check's maximum acceptable vector difference between internal and external compass after vectors are normalized to field length of 1.0
-#ifndef COMPASS_ACCEPTABLE_VECTOR_DIFF
-  #define COMPASS_ACCEPTABLE_VECTOR_DIFF    0.75f    // pre arm compass check will fail if internal vs external compass direction differ by more than 45 degrees
- #endif
-
 //////////////////////////////////////////////////////////////////////////////
 //  OPTICAL_FLOW
 #ifndef OPTFLOW
diff --git a/ArduCopter/motors.cpp b/ArduCopter/motors.cpp
index d40e91174a..4cceabbcc1 100644
--- a/ArduCopter/motors.cpp
+++ b/ArduCopter/motors.cpp
@@ -365,25 +365,13 @@ bool Copter::pre_arm_checks(bool display_failure)
             return false;
         }
 
-#if COMPASS_MAX_INSTANCES > 1
         // check all compasses point in roughly same direction
-        if (compass.get_count() > 1) {
-            Vector3f prime_mag_vec = compass.get_field();
-            prime_mag_vec.normalize();
-            for(uint8_t i=0; i<compass.get_count(); i++) {
-                // get next compass
-                Vector3f mag_vec = compass.get_field(i);
-                mag_vec.normalize();
-                Vector3f vec_diff = mag_vec - prime_mag_vec;
-                if (compass.use_for_yaw(i) && vec_diff.length() > COMPASS_ACCEPTABLE_VECTOR_DIFF) {
+        if (!compass.consistent()) {
                     if (display_failure) {
                         gcs_send_text_P(SEVERITY_HIGH,PSTR("PreArm: inconsistent compasses"));
                     }
                     return false;
                 }
-            }
-        }
-#endif
 
     }