https://devzone.nordicsemi.com/f/nordic-q-a/17547/update-characteristic-every-1-second-with-notification-while-ci-set-to-3-secondsHi, i update my characteristic every 1 second with a new value. the notification is set for the characteristic and it will notify my phone about the new value. at the same time i set the connection interval to between 3 seconds to 3.5 seconds. en-USTelligent Community 13Mon, 07 Nov 2016 14:01:19 GMThttps://devzone.nordicsemi.com/thread/67465?ContentTypeID=1Mon, 07 Nov 2016 14:01:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:aed6d1c0-4efc-4ff8-8eaa-8b4d42c54635Petter Myhre<p>I&#39;m not sure what you mean by that you are updating your characteristic value. I&#39;m guessing that you are just sending notifications by calling sd_ble_gatts_hvx(), and that you are not calling sd_ble_gatts_value_set().</p> <p>Every time sd_ble_gatts_hvx() is called and returns NRF_SUCCESS the notification will be put into a buffer and sent in the next <strong>available</strong> connection interval. If there is no buffer available it will return BLE_ERROR_NO_TX_PACKETS, which means that the notification will not be sent, and you must retry at a later point in time. So if you have buffered 3 notifications these will all be sent, not only the last one.</p> <p>The central device dictates the CI, the only thing the peripheral can do is to send a <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s130.api.v2.0.1/group___b_l_e___g_a_p___c_p_u___m_s_c.html?cp=3_6_2_1_0_2_1_3_7">CPU request</a>, then it&#39;s up the central to accept or reject this request. Also, at least on Android you can request connection priority with <a href="https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#requestConnectionPriority(int)">this</a> API.</p><div style="clear:both;"></div>