Question 33663 in React native Question posted in
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iOS BLE unstable connection – React native

I’m currently developing a react native app in combination with a device. The device and the app communicate via BLE. So far everything works as expected but I’m having issues with the connection stability of the iOS app and the device. What would happen is that the device would connect and I can update some characteristics but it would regularly either disconnect with a CBErrorDomain 7 or the response for a write would timeout. The implementation on the app or device side does not seem to be the problem as Android works stable and the device also disconnects when connecting with the LightBlue app.

I’ve already updated the BLE connection parameters as suggested here:
https://developer.apple.com/library/archive/qa/qa1931/_index.html.
This has increased the stability but did not resolve the problems completely. I’ve tried playing around with the values but so far no luck.

The current set of parameters we are using are:

conn_min_interval: 15
conn_max_interval: 15
conn_latency: 0
supervision_timeout: 2000
adv_min_interval: 1285
adv_max_interval: 1285

My question now would be if somebody has an idea what other things I could check or which parameter to tune?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Finally, I've found the answer to my problem. The problem was that the pairing procedure of the BLE server was faulty and thus iOS was unable to have a stable connection. Now that this is fixed the connection is very stable.

    I'm still unsure why iOS was able to have any communication at all without the pairing but I hope that this helps some people in the future.


  2. 0

    Are you checking the maximumWriteValueLength and making sure your writes are smaller than this? A likely cause of your problems is overwhelming the device and it fails to keep up with sending ACKs. What version of Bluetooth does your device support, and does it implement DLE (Data Length Extension)?

    Your conn_min_interval and conn_max_interval are suspicious. Asking for 15ms with no leeway is likely to negotiate to 30ms instead. (See 41.6 Connection Parameters) Is your device comfortable with being re-negotiated to something other than 15ms? Can your device actually keep up with 15ms and no connection latency if it does get that? I’m betting it can’t. Try setting your connection interval to 30ms (or even a bit slower), and you might even try setting your connection latency to 1 to make the connection a bit more forgiving (though I’d focus more on slowing the CI than increasing latency; increasing latency would be more of a hack in this case).

    All my suspicions are around your peripheral not keeping up with its side of the connection. If you have any synchronous activities in response to the data, you need to make sure that it’s not blocking your BLE stack from sending the required responses.

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