WIP: Enable reading of sensor data

[thePanz]

Rebase of #894 from @atx

[danielegobbetti]

+1 for me (but I don't have a miband 2 to test)

[thePanz]

@danielegobbetti I am working on it, but this is my first project for Android. I am still looking for some hints and tips to how to test/debug on my device... any help? :)

[ligantx]

i have mi band 2 and i want to test the raw accelerometer data, but i dont know how to use the submitted code... i downloaded Gadgetbridge app and paired my mi band 2..but there is no Fetch sensor data option in Debug...do i have to do any firmware update?

[thePanz]

@jimkaragian this feature is not shipped with the app, you need to compile the source code and run the "self-compiled" app on your phone.
I had no time to continue this Pull-Request, sorry

[ligantx]

@thePanz sorry for asking but im totally new to this area..how to compile an apk?
i mean normally there is a make file etc..
now i see there is a gradle folder (and gradle is a build tool right?)...so i download the Gadgetbridge-master file, change the code to your_code for Mi Band 2..and then compile it with gradle? (is there any tutorial or something for this procedure?)
thank you in advance..(i can delete the comment if its considered off-topic)

[thePanz]

@jimkaragian about the code: you can just clone my repository :) and yes, graddle is a building tool: I use IntelliJ to compile the code, but had to reset my machine and I don't have a building environment anymore at the moment.

Hope any of the maintainers will help here with the "compiling" questions, it could be cool if such instructions were available in the main repository too, under a how to compile section? @danielegobbetti

[h3ndrik]

is this also implemented in the mi band 3 firmware?

[thePanz]

@h3ndrik I have no clue about the MiBand3. Actually I wasn't even able to test this on my MiBand2 :(

[Epictek]

Did some work on parsing the output to XYZ values.

diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband2/MiBand2Support.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband2/MiBand2Support.java
index 7773ca4f..85108b45 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband2/MiBand2Support.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband2/MiBand2Support.java
@@ -1163,13 +1165,16 @@ public class MiBand2Support extends AbstractBTLEDeviceSupport {
      * @param value The data bytes
      */
     private void handleSensorData(byte[] value) {
-        String string = "";
-        for (byte b : value) {
-            string = string.concat(String.format(" 0x%4x", b));
-        }
-        LOG.warn("Received sensor data:" + string);
-
-        if ((value.length - 2) % 6 != 0) {
+        int i = 2;
+        if (value.length >= 2 && (value.length - 2) % 6 == 0) {
+            while (i < value.length) {
+                double x = (((value[i] & 255) | ((value[i + 1] & 255) << 8)) << 16) >> 16;
+                double y = (((value[i + 2] & 255) | ((value[i + 3] & 255) << 8)) << 16) >> 16;
+                double z = ((((value[i + 5] & 255) << 8) | (value[i + 4] & 255)) << 16) >> 16;
+                LOG.warn("X: " + x + " Y: " + y +" Z: " + z);
+                i += 6;
+            }
+        } else {
             LOG.warn("Got unexpected sensor data with length: " + value.length);
         }
     }

and here is some example output

2018-08-30 02:27:56.722 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -76.0 Y: 200.0 Z: 103.0
2018-08-30 02:27:56.725 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -81.0 Y: 199.0 Z: 104.0
2018-08-30 02:27:56.726 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -80.0 Y: 200.0 Z: 102.0
2018-08-30 02:27:56.734 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -84.0 Y: 199.0 Z: 102.0
2018-08-30 02:27:56.736 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -80.0 Y: 200.0 Z: 103.0
2018-08-30 02:27:56.736 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -80.0 Y: 195.0 Z: 108.0
2018-08-30 02:27:56.744 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -81.0 Y: 199.0 Z: 104.0
2018-08-30 02:27:56.745 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -79.0 Y: 200.0 Z: 103.0
2018-08-30 02:27:56.746 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -82.0 Y: 201.0 Z: 103.0
2018-08-30 02:27:56.755 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -88.0 Y: 200.0 Z: 96.0
2018-08-30 02:27:56.755 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -72.0 Y: 195.0 Z: 96.0
2018-08-30 02:27:56.756 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -79.0 Y: 198.0 Z: 99.0
2018-08-30 02:27:56.762 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -80.0 Y: 194.0 Z: 94.0
2018-08-30 02:27:56.763 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -89.0 Y: 184.0 Z: 94.0
2018-08-30 02:27:56.763 17391-17415/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -89.0 Y: 187.0 Z: 83.0
2018-08-30 02:27:56.771 17391-17414/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -87.0 Y: 188.0 Z: 63.0
2018-08-30 02:27:56.772 17391-17414/nodomain.freeyourgadget.gadgetbridge W/nodomain.freeyourgadget.gadgetbridge.service.devices.miband2.MiBand2Support: X: -104.0 Y: 177.0 Z: 60.0