From 17743dc4137425ab0f511d12352683255033a79a Mon Sep 17 00:00:00 2001
From: Jonny Roeker <jonny.roeker.public@t-online.de>
Date: Sat, 25 May 2024 17:42:40 +0200
Subject: [PATCH] =?UTF-8?q?AP=5FCompass:=20Scale=20adjusted=20QMC5883L=20?=
 =?UTF-8?q?=09ge=C3=A4ndert:=20=20=20=20=20=20=20libraries/AP=5FCompass/AP?=
 =?UTF-8?q?=5FCompass=5FQMC5883L.cpp?=
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---
 libraries/AP_Compass/AP_Compass_QMC5883L.cpp | 24 +++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/libraries/AP_Compass/AP_Compass_QMC5883L.cpp b/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
index ad1bea4989..ea36cbd7a9 100644
--- a/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
+++ b/libraries/AP_Compass/AP_Compass_QMC5883L.cpp
@@ -27,12 +27,13 @@
 #include <AP_HAL/AP_HAL.h>
 #include <AP_HAL/utility/sparse-endian.h>
 #include <AP_Math/AP_Math.h>
+#include <GCS_MAVLink/GCS.h>
 
 #define QMC5883L_REG_CONF1 0x09
 #define QMC5883L_REG_CONF2 0x0A
 
 // data output rates for 5883L
-#define QMC5883L_ODR_10HZ (0x00 << 2)
+#define QMC5883L_ODR_10HZ  (0x00 << 2)
 #define QMC5883L_ODR_50HZ  (0x01 << 2)
 #define QMC5883L_ODR_100HZ (0x02 << 2)
 #define QMC5883L_ODR_200HZ (0x03 << 2)
@@ -46,8 +47,8 @@
 
 #define QMC5883L_OSR_512 (0x00 << 6)
 #define QMC5883L_OSR_256 (0x01 << 6)
-#define QMC5883L_OSR_128	(0x10 << 6)
-#define QMC5883L_OSR_64	(0x11	<< 6)
+#define QMC5883L_OSR_128 (0x10 << 6)
+#define QMC5883L_OSR_64	 (0x11 << 6)
 
 #define QMC5883L_RST 0x80
 
@@ -99,14 +100,14 @@ bool AP_Compass_QMC5883L::init()
     	 goto fail;
     }
 
+    /* Registers 0x20 and 0x21 are not documented in the data sheet and do not show any function during operation */
+
     if (!_dev->write_register(0x0B, 0x01)||
-    	 !_dev->write_register(0x20, 0x40)||
-		 !_dev->write_register(0x21, 0x01)||
-		 !_dev->write_register(QMC5883L_REG_CONF1,
-						QMC5883L_MODE_CONTINUOUS|
-						QMC5883L_ODR_100HZ|
-						QMC5883L_OSR_512|
-						QMC5883L_RNG_8G)) {
+        !_dev->write_register(QMC5883L_REG_CONF1,
+				QMC5883L_MODE_CONTINUOUS|
+				QMC5883L_ODR_100HZ|
+				QMC5883L_OSR_512|
+				QMC5883L_RNG_8G)) {
     		  	  goto fail;
      }
 
@@ -165,7 +166,8 @@ void AP_Compass_QMC5883L::timer()
     	le16_t rz;
     } buffer;
 
-    const float range_scale = 1000.0f / 3000.0f;
+    /* Most modules deliver a value four times higher */
+    const float range_scale = 1000.0f / (3000.0f  * 4.0f);
 
     uint8_t status;
     if(!_dev->read_registers(QMC5883L_REG_STATUS,&status,1)){