https://devzone.nordicsemi.com/f/nordic-q-a/13050/issue-when-sending-multiple-notifications-consecutively-on-single-characteristicI just ran a few experiments on calling sd_ble_gatts_hvx() multiple times based on SDK v10&#39;s ble_app_uart example. I have configure the app so that it for each external event, for 15 times, it increments a byte and call sd_ble_gatts_hvx() with that byteen-USTelligent Community 13Thu, 07 Apr 2016 21:18:30 GMThttps://devzone.nordicsemi.com/thread/49750?ContentTypeID=1Thu, 07 Apr 2016 21:18:30 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3bb0f235-c100-4208-a788-7e0321c16ad8John<p>When you call sd_ble_gatts_hvx it doesn&#39;t immediately send your packet. The packet is queued up in the stack and the function call returns. The stack only has a limited number of buffers (6) before it runs out of buffers to hold your packets. When that happens the stack will return a BLE_ERROR_NO_TX_BUFFERS error code and you need to wait for a BLE_EVT_TX_COMPLETE from the stack before you can queue up more packets to send.</p> <p>This answer may help you out with this: <a href="https://devzone.nordicsemi.com/question/880/s110-sending-multiple-notifications-per-connection-event/">TX Complete</a></p><div style="clear:both;"></div>