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NRF51422 Bluetooth: Long time between send and receive from message

Fabrice

Hello together,

I' am working on a Bluetooth application and have a problem with the transmitting time of the Bluetooth.

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In this Screenshot you can see the end of my command which i want to send from my NRF422 to my NRF422 Dongle. The second peak from the Debug pin indicates the send of the "Request Transfer" for the Bluetooth message. The Buffering just takes 0.26ms.

image description

In this image I receive and Send my Bluetooth message via UART. (second peak debug pin). The message i received is exactly the same i sent and it is working every time. The Time for the Buffering is just 0.41ms.

image description

Now my Problem: The Time in between send and receive is about 160ms and that's to long. Does someboy has experience with the Bluetooth Stack and knows what could cause the problem?

Thank you.

Best regards,

Fabrice

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    Hi Fabrice,

    When you mark the point of "Request Transfer" what exactly is called at that point ? You queued the command using sd_ble_gattc_write() or sd_ble_gatts_hvx() ? Note that when you call those command, if there is other commands in the buffer, they will be sent first.

    And a BLE packet can only be sent on a connection event, not when you call the API. So if you have a very long connection event, for example 500ms, a packet may have to wait up to 500ms before it's send (with the condition that there is no other packet is queued prior).

    You should check your connection event, try to change it to a lower one for example 7.5ms and check if it can reduce the latency.

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  • 0

    Hi Fabrice,

    When you mark the point of "Request Transfer" what exactly is called at that point ? You queued the command using sd_ble_gattc_write() or sd_ble_gatts_hvx() ? Note that when you call those command, if there is other commands in the buffer, they will be sent first.

    And a BLE packet can only be sent on a connection event, not when you call the API. So if you have a very long connection event, for example 500ms, a packet may have to wait up to 500ms before it's send (with the condition that there is no other packet is queued prior).

    You should check your connection event, try to change it to a lower one for example 7.5ms and check if it can reduce the latency.

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