Android issues with BLE

[soumil]

Hi,

I am facing some issues on the Android part of the BLE.

Firstly it takes around 20 seconds for the android phone in scanning mode to find the nordic board. This happen only for the first time and not after that.

I also face a lag when connection is established and it takes around 10 seconds to display the result on the phone.

I am using a moto e phone which has android 6.0. Any particular reasons on why this happens.

[Petter Myhre]

What app are you using to scan? What advertising interval are you using? What do you mean by "This happen only for the first time and not after that"? What connection interval are you using? How are you sending the information to the smart phone? Does the smart phone read the result, or does the nRF5 send a notification with the result?

[soumil]

We have made our own app using the android Ble library. The advertising interval i am using on the nordic board is 500ms. When i say it happens only for one time and not after that means that when scanning is done for the first time, the phone takes a long time to find the nordic device but once paired/connected once, then the next time device discovery happens quickly. How do you set the connection interval in android?The peripheral connection parameters are set as min to 500 ms and max to 1000 ms. The smartphone reads the custom characteristic after connection.

[Petter Myhre]

Could it be that you are using a different advertising interval when you restart advertising on a disconnect?

You could try decreasing the advertising interval and see if that makes a difference. Or you could try changing the SCAN_MODE_LOW_LATENCY when you scan.

See this for how to check the actual connection interval.

[soumil]

Okay thanks would try this. Do we know for different scan modes what are the scanning intervals set on the phone side. For example in case of SCAN_MODE_LOW_LATENCY, what is the scanning interval? Also can i change the connection parameters from the firmware side. Is it using connection params update ?

[Petter Myhre]

I don't know what the scan intervals/windows are on Android, but I found this. As a peripheral you can only request a connection parameter update, it is up to the central device to actually do it. See this for more information.