About disconnection issue on IOS

[muralikrishnan]

Hai,

we are using nRF52832  and Nordic connect for our development and testing work

we are facing disconnection issue on android after ~3min so we changed the CONNECTION_MIN_INTERVAL=8 to 15ms,CONNECTION_MAX_INTERVAL=10 to 20ms

now andriod disconnection issue solved but IOS disconnection issue was not yet solved using Nordic connect ,

Test case

we changed the interval of min and max interval =(30 to 50) (not working)

we changed the interval of min and max interval =(20 to 100) (not working)

so kindly proved some solution for this 

[Mttrinh]

Hi,

we changed the interval of min and max interval =(30 to 50) (not working)

we changed the interval of min and max interval =(20 to 100) (not working)

Not totally sure what you mean by this, can you clarify? What is the min interval and what is the max interval?

Also check out the Accessory Design Guidelines for Apple Devices, under "25.6 Connection Parameters".

[Mttrinh]

What example are you using? Is it unmodified except for the connection parameter?

Which SDK and Softdevice are you using?

[muralikrishnan]

hi Mttrinh,

we are used sdk=15.2 and soft device version=6.1.0

[Mttrinh]

Hi,

Could you also tell me which example you are using and if you have made any modifications to it?

Could you also tell me which iOS devices you used for testing and which iOS version they are running? If you have only tested with one iOS device, could you try with other iOS devices as well?

[muralikrishnan]

Hi,

we used i phone 10 XR  then no modification done

[Mttrinh]

Hi,

Could you answer all of my questions in the previous reply? It helps me narrow it down, and easier for me to help you.

Mttrinh said:

Could you also tell me which example you are using and if you have made any modifications to it?

Could you also tell me which iOS devices you used for testing and which iOS version they are running? If you have only tested with one iOS device, could you try with other iOS devices as well?

[SorenKonekt]

Hello, we have exactly same issue on an NRF52832, softdevice S132, NRF SDK 15, various iphone models, but especially iphone 7 (13.3) and iphone 6s (newest possible IOS).. iphone 6 seems to be much less affected by this than 6s for some reason. Perhaps due to the IOS version.
When I put the iphone aside and sleep the screen, I can see on device log that connection parameters are changed to:
min conn. interval: 480ms
max conn. interval: 480ms

conn. timeout : 4s

slave latency: 0

Phone and device will eventually loose connection, and this seems to be very random. Sometimes it takes several hours to reproduce, and sometimes it happens 4-6 times in one hour.

This is getting very critical and we are ready to try more or less anything. Please Mttrinh if you can provide us with any guidelines or ideas, this is very useful. 

Best

Søren

[Mttrinh]

Hi,

What have you set your connection parameteres to? If you haven't already done so, I would recommend checking out the "Accessory Design Guidelines for Apple Devices" link in my first reply.

What softdevice version are you using? Are you using an example from our SDK to test this? Have you done any modifications to the example?

If you have access to other phones, could you try testing with the same models but different iOS? To check if the iOS version affects the connection.

Also a sniffer trace would be helpful to see what happens over-the-air in the different scenarios.

[SorenKonekt]

Hello Mttrinh

Connection parameters are set according to Apple's accesory design guidelines.
Min connection interval is 300ms and max is 500ms

we are using soft device 132

Our code is much customized to fit our needs, so I'm sure our HW team has done modifications (or made it from scratch, I'm not sure). 

here is sniffer trace. one with normal disconnect and one with disconnect happening despite device and phone are very near to each other. 

https://docs.google.com/spreadsheets/d/1zdk1QG4YRO6hO3bD8OvXlyyPiJ7sKyVfh9bP5hiPtTE/edit?usp=sharing

it's not easy for me to change IOS since we cannot downgrade it, and we don't have plenty of iphone 6s's lying around (the ones that have the issue)

[Mttrinh]

Hi,

I have taken a look at the sniffer traces that you sent me. I noticed that the trace for the disconnect issue, it seems that the device doesn't go back to advertising normally after the disconnect. Could you try to debug your application and find out where it hangs and what error code this function returns when the disconnect occur?

[SorenKonekt]

yes, i am currently trying to reproduce the issue with a Bluetooth Profiler installed on the test phone. This should enable some more extensive system logging. Will get back to you asap. Thank you!

[SorenKonekt]

Mttrinh

so i reproduced the issue (phone and device disconnects although they are 50cm apart on a table). 

Phone bluetooth profiler system logs are here https://drive.google.com/drive/folders/1fkDzhdO8SILxDQgkYUUUaHPzM1lNbV_H?usp=sharing

And this is the message we see in our app log when the disconnect happens:

2020/01/13 10:23:29:952  BLE service disconnected with peripheral. UUID: 4ACCEE9B-0B3D-1EA1-1ED9-EF3E8A03DEBD. Error description: The connection has timed out unexpectedly.