iPhone 7 series dropping connection after approximately 40 seconds

[Aleksandar Kahriman]

Hello,

Let me start off by saying that in our use case we are transferring large amounts of data (megabytes) through BLE. This works fine on iPhone 6s+, iPhone SE, iPhone X, but not on the iPhone 7 series. On both iPhone 7 and iPhone 7+ the connection just drops after approximately 40 seconds. iOS logs state "Unknown Error". I implemented DFU protocol in the same application and that works fine, never dropping connection.

My connection parameters are:

Current config

  {

    // Minimum Connection Interval in 1.25 ms units

    MSEC_TO_UNITS(7.5, UNIT_1_25_MS),    

    // Maximum Connection Interval in 1.25 ms units

    MSEC_TO_UNITS(7.5, UNIT_1_25_MS),

    // Slave Latency in number of connection events

    0,

    // Connection Supervision Timeout in 10 ms units

    MSEC_TO_UNITS(250, UNIT_10_MS),

  }

Thanks in advance for showing interest in this problem. If I can supply you with any further information, please don't hesitate to ask.

[Bjørn Kvaale]

Could you please upload a sniffer trace? That should make it easier to debug this issue.

[Aleksandar Kahriman]

The only logs I have access to at the moment are RTT Viewer terminal logs from firmware side. Can you please explain to me how to get the sniffer trace and if I can do that without changing anything in the firmware?

[Bjørn Kvaale]

Sorry for the delayed response. I have been on vacation. Download the sniffer user guide v2.2. here. The sniffer trace just sniffs the bluetooth communication between the two devices. You will not have to make any changes in the FW, however you will need another nrf51 or 52 based device to use as a sniffer.