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Nordic Case Info
  • Case ID: 284832
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LLPM questions

user91008

Dear Nordic engineers

I ask a question about LLPM some time ago and I accidentally closed the discussion.Now there is a new follow up.

devzone.nordicsemi.com/.../llpm-questions

1、This issues has a FAE is working on it.We intercepted the packet and found that communication packet in the air is normal.This problem is because the callback function is not entered.Please give me some  good suggestions for this problem.  

2、Because this issues was only discovered during their internal testing, and there are no related complaints about products currently on the market, we suspect it is a problem with the test computer.Can be put on hold for now.

Now they have some new questions and need your help.

1、How to modify the connection interval of LLPM?We try to use function call set_conn_params in ble_conn_params.c to increase the connection interval  when received USB_DC_SUSPEND event.This is correct.When LLPM mode is enabled,the connection interval parameter ranges from 1000us to 7000us.Now we hope that the power consumption can be lower,so we would like to set the connection interval to be larger,but if modify the larger parameter ,it will not take effect.Is there any other way to modify the connection interval?

2、The LLPM mode communicates with the dongle.When there is a lot of communicates data,the event queue will overflow,causing the connection to be disconnected.Please tell me,how to increase the size of the event queue?

Thank you for your support and best regards~

  • 0

    /** @brief Connection Interval in microseconds. Valid range is 7,500 us to 4,000,000 us in 1,250
    * us steps. If LLPM mode is enabled, parameters in the range 1,000 us to 7,000 us in
    * 1,000 us steps are also accepted.

    1. From your screenshot from the SDC documentation i can see connection intervals specified by Bluetooth (from 7.5 ms increadsed with 1.25 ms step) should work fine too. What value do you use? What was the error code that you observed?

    2. What is the disconnection reason? How you know that the disconnection is related to the event queue overflow? We have not seen anything similar on our dongles, do you introduce additional functionalities to the dongle (so that it performs more operations that could delay Bluetooth processing)?

    Best regards,
    Kenneth

  • 0 in reply to user2111

    Dear Kenneth

    1、The following TXT file is the LOG printed after we failed to modify the connection interval.

    2、In addition, we have solved the problem of event queue overflow. Thanks again for your support.

    3、About the problem of abnormal CAP and NUM indicators，We intercepted the packet and found that communication packet in the air is normal.This problem is because the callback function is not entered.

    Please give me some  good suggestions for this problem.  

    Best regards.

  • 0 in reply to user91008

    Hello,

    1. Are you sure you are not getting any errors from bt_conn_le_param_update()? Is the packet sent on-air? It looks like the interval you are trying to set is (hex) d01 -> 3329, this seems very high, not sure if this is allowed when using a 4second supervisor timout. Maybe you can try with some smaller intervals first, e.g. 10ms or 100ms, and a latency of 10.

    2. Thanks for the update.

    3. I have forwarded your latest input internally, will let you know when I hear back.

    Best regards,
    Kenneth

  • 0 in reply to user2111

    Dear Kenneth

    My city has recently been working from home for a week due to the covid-19 control. I only received the customer update today. I am very sorry.

    1、Setting it to d01 means that the connection interval should be 1ms and d07 means 7ms.

    2、Is there a new update about  the problem of abnormal CAP and NUM indicators?

    Thank you for your support.

    Best regards

  • 0 in reply to user91008

    1. Is there any on-air sniffer log you can share to show what may be happening here on-air? For instance I can find the following limitation, but I don't see how that apply here:

    DRGN-11297: Maximum connection interval of 10 ms before entering LLPM-mode

    The maximum connection interval that can be active when switching to a connection interval of 1 ms is 10 ms.

    Workaround: An application that needs to use a higher interval than 10 ms must perform two connection updates to use 1 ms connection interval:

    • A first update to 10 ms connection interval.

    • A second update to 1 ms connection interval.

    https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/softdevice_controller/limitations.html# 

    It says (Connection lost), but do you have any indication of the disconnect reason on peripheral and central?

    2. I will ping the team again if there is any update.

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