From a66658c8296d19b7b7188f4f2ea3cd06bbe483a5 Mon Sep 17 00:00:00 2001
From: srwareham <ebriouscoding@gmail.com>
Date: Fri, 8 Mar 2019 08:37:21 -0500
Subject: [PATCH] Fix force QN-Scale to KG (#429)

added unit support for QN scale
---
 .../core/bluetooth/BluetoothCommunication.java    |  8 ++++++++
 .../core/bluetooth/BluetoothQNScale.java          | 15 +++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothCommunication.java b/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothCommunication.java
index 12063d1f..c57a313d 100644
--- a/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothCommunication.java
+++ b/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothCommunication.java
@@ -426,6 +426,14 @@ public abstract class BluetoothCommunication {
         return checksum;
     }
 
+    protected byte sumChecksum(byte[] data, int offset, int length) {
+        byte checksum = 0;
+        for (int i = offset; i < offset + length; ++i) {
+            checksum += data[i];
+        }
+        return checksum;
+    }
+
     /**
      * Test in a byte if a bit is set (1) or not (0)
      *
diff --git a/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothQNScale.java b/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothQNScale.java
index 1db66cf2..b8bfb628 100644
--- a/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothQNScale.java
+++ b/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothQNScale.java
@@ -95,8 +95,19 @@ public class BluetoothQNScale extends BluetoothCommunication {
                 setIndicationOn(CUSTOM2_MEASUREMENT_CHARACTERISTIC);
                 break;
             case 2:
-                // write magicnumber 0x130915011000000042 to 0xffe3
-                byte[] ffe3magicBytes = new byte[]{(byte) 0x13, (byte) 0x09, (byte) 0x15, (byte) 0x01, (byte) 0x10, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x42};
+                final ScaleUser scaleUser = OpenScale.getInstance().getSelectedScaleUser();
+                final Converters.WeightUnit scaleUserWeightUnit = scaleUser.getScaleUnit();
+                // Value of 0x01 = KG. 0x02 = LB. Requests with stones unit are sent as LB, with post-processing in vendor app.
+                byte weightUnitByte = (byte) 0x01;
+                // Default weight unit KG. If user config set to LB or ST, scale will show LB units, consistent with vendor app
+                if (scaleUserWeightUnit == Converters.WeightUnit.LB || scaleUserWeightUnit == Converters.WeightUnit.ST){
+                    weightUnitByte = (byte) 0x02;
+                }
+                // write magicnumber 0x130915[WEIGHT_BYTE]10000000[CHECK_SUM] to 0xffe3
+                // 0x01 weight byte = KG. 0x02 weight byte = LB.
+                byte[] ffe3magicBytes = new byte[]{(byte) 0x13, (byte) 0x09, (byte) 0x15, weightUnitByte, (byte) 0x10, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00};
+                // Set last byte to be checksum
+                ffe3magicBytes[ffe3magicBytes.length -1] = sumChecksum(ffe3magicBytes, 0, ffe3magicBytes.length - 1);
                 writeBytes(CUSTOM3_MEASUREMENT_CHARACTERISTIC, ffe3magicBytes);
                 break;
             case 3: