BLE Accelerometer bytes

CybMcloud

I'm building a small app using bluetooth low energy communication, for new C series board (firmware version 1.2.1)

so i was able to control LED lights, and to subscribe for notifys of button push event

but I can't make accelerometer to work

one of the reasons being - can't find documented description of what bytes to send, I've tried to analyze some of available examples i could find and it seems like Accelerometer is module number 3, then seems like i should be sending 3 in the second byte, then 01 or 00? - and I'm going through this "guessing" process instead of just being able to read somewhere this byte means this, and this byte - that

also which UUID should I allow notifications from to receive accelerometer updates?

I'm setting it to main RX characteristic, and that's how i get butten push notifications, but may be problem with accelerometer is that i am not addressing right UUID or characteristic?

this is greeting from my board when i connect it:

["1800","1801","180f","180a","326a9000-85cb-9195-d9dd-464cfbbae75a"],"characteristics":[
{"service":"1800","characteristic":"2a00","properties":["Read","Write"]},
{"service":"1800","characteristic":"2a01","properties":["Read"]},
{"service":"1800","characteristic":"2a04","properties":["Read"]},
{"service":"1801","characteristic":"2a05","properties":["Indicate"],"descriptors":[{"uuid":"2902"}]},
{"service":"180f","characteristic":"2a19","properties":["Read","Notify"],"descriptors":[{"uuid":"2902"}]},
{"service":"180a","characteristic":"2a29","properties":["Read"]},
{"service":"180a","characteristic":"2a24","properties":["Read"]},
{"service":"180a","characteristic":"2a25","properties":["Read"]},
{"service":"180a","characteristic":"2a27","properties":["Read"]},
{"service":"180a","characteristic":"2a26","properties":["Read"]},
{"service":"326a9000-85cb-9195-d9dd-464cfbbae75a","characteristic":"326a9001-85cb-9195-d9dd-464cfbbae75a","properties":["Read","WriteWithoutResponse","Write"]}, ------------(main TX uuid)
{"service":"326a9000-85cb-9195-d9dd-464cfbbae75a","characteristic":"326a9006-85cb-9195-d9dd-464cfbbae75a","properties":["Read","Notify"],"descriptors":[{"uuid":"2902"}]}]} --------------- (main RX uuid)

I've tried 180f->2a19 and it fires some single number(usually in range from 46 to 52) every... 10 seconds and that's it, so it's not an accelerometer

I have tried Reading all the other uuid->chars from this least, they read some static numbers, none of them begins with byte "3" - so not an accelerometer neither (btw would be also nice to see description of those uuids and where they come from)

variants of calling accelerometer I have tried so far are:

0x03, 0x03, 0x00, 0x00, 0x20, 0x00, 0x00 -> sample code says it's the command to start the accelerometer
0x03, 0x02, 0x01 - "enable x axis"
0x03, 0x04, 0x01 - "enable y axis"
0x03, 0x01, 0x01 - "enable z axis"

taken from: https://github.com/ldeluca/metawear/blob/master/plugins/com.lisaseacat.metawear/www/metawear.js

for example setting button to send notifications is 0x01, 0x01, 0x01 - and it works fine after I also setup notify subscription to main RX channel

another variant of accelerometer call, which I found in some JAVA program for more advanced CPro board or something like that was:

0x03, 0x0d, 0x04, 0x0a
0x03, 0x0a, 0x00, 0x14, 0x14, 0x14
0x03, 0x03, 0x20, 0x0c
0x03, 0x07, 0x07, 0x30, 0x81, 0x0b, 0xc0
0x03, 0x01, 0x01

taken from some java example... from this example: https://github.com/brainexe/node-metawear/blob/master/src/registers/accelerometer.js

so only thing I can understand from here is that 03 is truly accelerometer module ID, but what do other parameters do - unkown, neither of these examples start acelerometer(or I am not reading proper UUID/char combination)

no error is returned from Cboard neither, button push and LED control keeps on working properly

thanks for any help

Eric

Is there a reason why you are not using the Android API?  

CybMcloud

I'm writing on phonegap and will need to integrate this functionality into a lot of different things also developed using phonegap

Eric

The C++ library serves as the documentation of the MetaWear protocol; you should check out the source code + unit tests to find what you need.  Since you're using a C board, the bmi160 accelerometer implementation and unit tests will be of particular interest.

Alternatively, if I understand how PhoneGap works, we have a Cordova plugin that should cover what you need.

CybMcloud

I'll check everything above

about cordova plugin: I was unable to import it to application, either it's outdated version or something doesn't work with it

neither pgb nor npm versions can be found by phonegap

CybMcloud

as much as i understand from C++ example, BMI160 start command should look as 3,1,1 right?

will accelerometer updates coming in through the normal Rx port ( 9006) or different one?

CybMcloud

so thank you, i was able to find appropirate bytes in .py test files

for anyone who might be looking for same data, for BMi160 accelerometer, starting commands are:

0x03, 0x04, 0x01
0x03, 0x01, 0x01
0x03, 0x02, 0x01, 0x00

this pretty much fires it up and the information comes flowing into main Rx "port" (incase if u have subscribed for it's notifications beforehand ofcourse)

for some basic configuration use:

0x03, 0x03, 0x27, 0x03 (setting to 50 hz)
0x02, 0x03, 0x28, 0x0c (setting range to 16G)

turning off:
0x03, 0x02, 0x00, 0x01
0x03, 0x04, 0x00
0x03, 0x01, 0x00

lgleasain

Were you using the Cordova plugin here https://github.com/mbientlab-projects/cordova-plugin-metawear  ?  I'm circling back around to this,  but have already implemented accelerometer and LED functionality in the current version.

Can you give me some more information about your application so that I can help to get this plugin working for you?  IE:  What is the problem you are running into when trying to include the plugin,  what version of phonegap/cordova are you running etc..

Long term it is going to save you a lot of work the one we are working on instead of you needing to roll your own.