How to find out when BLE_NUS has successfully send a packet?

[justPassingBy]

Hello everyone,

Currently I'm altering the "ble_app_uart" and "ble_app_uart_c" examples (both under examples/ble_peripheral) to suit my needs. What I currently need to know is exactly when the packet has arrived on the other side. To my understanding the Bluetooth part will receive an acknowledgement on successful transmission, so this should technically be possible. However, I don't know what event will be triggered (so that I can attach some code under the event handler) in that case. Does anyone else do?

Many thanks for your help.

Edit: To clarify, the Enhanced ShockBurst protocol for example has an event "NRF_ESB_EVENT_TX_SUCCESS", under the nrf_esb_event_handler, which is triggered whenever an acknowledgement has been received.

[justPassingBy]

Anyone? It seems like a pretty trivial use case.

[run_ar]

You will get an event, see the documentation for sd_ble_gatts_hvx. The event:BLE_GATTS_EVT_HVN_TX_COMPLETE.

Note that you won't necessarily get the event right away, it will be generated when the SD has time to do so. so the event will include a count of the number of freed tx buffers. Also note that BLE has "lasy ack" so the last packet sent by the slave in a connection event will not be acked on the LL until the next connection event. So I'm afraid BLE is not suited to know exactly when the packet arrives on the other side. What accuracy do you need?