Setting connection parameters

Alex · October 2016

Hi all,

In a previous thread that I wrote, Eric mentioned settings the max connection interval to 7.5 to be able to stream at 50Hz. I previously already played with the settings, and was using something around 15.

When trying to set it to 7.5, I noticed a regression in the behaviour. After diving into this for a bit I noticed that any maxConnectionInterval below 12 is not accepted by the sensor. To be sure the minConnectionInterval wasn't the problem, I explicitly set that one to 7.5.

I am using an R and CPro sensor with an Android (Cordova) application and both sensors show the same behaviour.

The flow is:

* connect sensor

* wait for Connected state

* set min/max interval and commit

If the max value is 12 or above I see the following in the Android log:

10-03 13:06:22.443: D/BluetoothGatt(23578): onClientConnParamsChanged() - Device=CE:EC:00:B4:84:F3 interval=9 status=0

But as soon as I change it to something lower, nothing is shown and the sensor can't keep up with the 50Hz.

Is this a bug? Or am I doing something wrong?

Alex · October 2016

And again I've probably found the answer myself. For anyone wondering, apparently Android 6+ changed to a minimum off 11.25. I've confirmed this with my device, and can verify this..

.

Whether or not this is an Android bug or on purpose is unclear to me. It is, however, really annoying. With something like cordova I now have to take the OS into consideration, while I would expect Android etc, to follow the BLE spec..

See:

http://stackoverflow.com/questions/34617061/android-6-0-marsmallow-ble-connection-parameters

https://code.google.com/p/android/issues/detail?id=199521

Setting connection parameters

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