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ble speed

chenwenbin

I want to speed up the ble transfer,  use the ble_app_uart example,  but the speed is too low ,  sniffer show that the notify pack moredata  is true , but  the follow pack is not the notify pack. what is the mean L2CAP Fragment pack , why so many packs  time is same

 

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    Hello,

    I want to speed up the ble transfer,  use the ble_app_uart example,  but the speed is too low ,

    Please have a look at the SoftDevice throughput documentation. If you make sure that your devices are using the same configuration as detailed in the throughput table you should see similar throughput. Especially with regards to connection interval, connection event length and MTU size.

    why so many packs  time is same

    You should not use the Time column, but instead, go into View and select Delta Time. This is the actual time between packets - and not the COM port time as shown by the Time field. Please do this, so you may accurately see how many packets  are sent each connection event.

    what is the mean L2CAP Fragment pack

    If a packet is bigger than the MTU size, the Link Layer breaks the packet into multiple fragments which it can send in multiple packets.

    sniffer show that the notify pack moredata  is true , but  the follow pack is not the notify pack.

    The most common reason for the central not prompting another packet when the peripheral has set moredata is that the connection event length does not allow for another transmission. Please increase your connection event length and see if this lets you send more packets per connection event.

    Best regards,
    Karl

  • 0 in reply to Karl Ylvisaker

    Is nrf 52810 not support data length extent (DLE)? What is the mean of connection event length

  • 0 in reply to chenwenbin

    Yes, the nRF52810 does indeed support Data Length Extension (DLE). DLE allows the devices to negotiate a payload larger than the original 27 byte limit of BLE prior to 4.2. So in essence, DLE lets you use PDU's of up to 251 bytes.

    Connection Event Length is how long the devices may communicate each event. Say for example that you are using a connection even length of 1 ms with a connection interval of 7.5 ms. In this case, every 7.5 ms there will be a connection event, in which the devices may communicate for a total of 1 ms each time. You can read more about this here, or visualize the impact of your connection parameters using the Online Power Profiler.

    Best regards,
    Karl

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  • 0 in reply to chenwenbin

    Yes, the nRF52810 does indeed support Data Length Extension (DLE). DLE allows the devices to negotiate a payload larger than the original 27 byte limit of BLE prior to 4.2. So in essence, DLE lets you use PDU's of up to 251 bytes.

    Connection Event Length is how long the devices may communicate each event. Say for example that you are using a connection even length of 1 ms with a connection interval of 7.5 ms. In this case, every 7.5 ms there will be a connection event, in which the devices may communicate for a total of 1 ms each time. You can read more about this here, or visualize the impact of your connection parameters using the Online Power Profiler.

    Best regards,
    Karl

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