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Nordic Case Info
  • Case ID: 331755
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Empty connection intervals after sending/receiving a complete packet

marklander

Hi guys,

 i show you an image here where I am sending from my board a text file ( about 75KB ) to nordic toolbox via nus, I use notify to send ( but I have similar situation when receiving from nrf toolbox).

Basically I see some empty connection interval ( 3 usually ) between a notify indication and the next one, also if probably data could be sent also in that period. I am using an MTU of 259 ( i will attach also sniffer log).

All is working, but obviously that silent of 3 connection intervals slows my data rate. Could that be an Android limitation? I tried with 3 android phones and seems identical, they all force my connection interval to 11.25 ms.

In red the event id 2938 with full packet incoming and notified, the 3 empty intervals in blue.

Full log:

empty_intervals.pcapng

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  • 0

    Hi,

    If the stack has data to send, I would not expect empty packets. How are you pushing the data in your implementation?

    Also, if you want a higher throughput I would consider using data length extension so that you can send longer packets also at the GAP layer and avoid fragmentation.

  • 0 in reply to Einar Thorsrud

    Ok some details more:

    • I am using a 100KB text file copied inside a macro in nrf toolbox to send an I am using write_without_response to send from master ( android device ) to slave ( my embedded board ) and notify in the other direction.
    • Due to my small microcontroller i am on s112 which not have the possibility to use DLE, but i tried also with that and I cannot see a big improvement. I can try again with s113 anyway which supports DLE.

    I was reading something similar here...post.

    Thanks for your support  and if I can send some more infos to get more data rate tell me if you need some logs...now I am still around a rough 9 to 11 KB/s

    Did another round activating DLE with S113:

    Also in the pic above you can see that some connection intervals are empty. Sniffer log below.4048.sniffer.pcapng.

    Here parameters of connection:

    And DLE req:

    Res:

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  • 0 in reply to Einar Thorsrud

    Ok some details more:

    • I am using a 100KB text file copied inside a macro in nrf toolbox to send an I am using write_without_response to send from master ( android device ) to slave ( my embedded board ) and notify in the other direction.
    • Due to my small microcontroller i am on s112 which not have the possibility to use DLE, but i tried also with that and I cannot see a big improvement. I can try again with s113 anyway which supports DLE.

    I was reading something similar here...post.

    Thanks for your support  and if I can send some more infos to get more data rate tell me if you need some logs...now I am still around a rough 9 to 11 KB/s

    Did another round activating DLE with S113:

    Also in the pic above you can see that some connection intervals are empty. Sniffer log below.4048.sniffer.pcapng.

    Here parameters of connection:

    And DLE req:

    Res:

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