https://devzone.nordicsemi.com/f/nordic-q-a/12730/ble-uart-send-bytesI&#39;m using ble_nus_string_send() to send 15 bytes over BLE UART. As expected it sends 15 bytes, however on occasion 14 bytes are sent instead of 15 bytes. Would there be a particular reason for this to occur? void uart_event_handle(app_uart_evt_ten-USTelligent Community 13Tue, 29 Mar 2016 13:28:25 GMThttps://devzone.nordicsemi.com/thread/48336?ContentTypeID=1Tue, 29 Mar 2016 13:28:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:52bcea7d-bcd4-4471-8815-4b714302a17cypearson<p>This error was due to a android app bug.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/48337?ContentTypeID=1Tue, 29 Mar 2016 11:00:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:54be3c6e-c9ad-4f8b-a1e0-f1191d1583e4Stefan Birnir Sverrisson<p>Hi</p> <p>Are you surely calling ble_nus_sting_send function with index = 15 every time? Any error code returned from ble_nus_sting_send function? Are you perhaps only sending one byte every time? To maximize throughput, you should set 20 bytes in each packet, i.e. call ble_nus_sting_send first when you have accumulated 20 bytes for transmission. One call to ble_nus_sting_send will transmit one data packet over BLE.</p> <p>Are you using the standard ble_app_uart example from nRF51 SDK 11.0.0? nRF51 or nRF52? What softdevice?</p> <p>Perhaps the <a href="https://devzone.nordicsemi.com/question/41090/what-does-sd_ble_tx_buffer_count_get-return/?answer=43938#post-id-43938">softdevice buffer</a> is full. In that case, you will receive error <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s110.api.v8.0.0/group__ble__err.html?cp=2_6_0_0_0_2_0_2_3#ga901e1bc3ccae29eff9fb31cabdbb5e02">BLE_ERROR_NO_TX_BUFFERS</a>. See also these threads <a href="https://devzone.nordicsemi.com/question/2540/understanding-ble_evt_tx_complete/">(1)</a> <a href="https://devzone.nordicsemi.com/question/72219/stream-live-sensor-data-from-ble_uart-application/?answer=72687#post-id-72687">(2)</a> and the documentation for <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s110.api.v8.0.0/group___b_l_e___g_a_t_t_s___f_u_n_c_t_i_o_n_s.html?cp=2_6_0_0_0_2_3_5_2#ga313fe43c2e93267da668572e885945db">sd_ble_gatts_hvx</a> which is the function used to send notification packets.</p><div style="clear:both;"></div>