https://devzone.nordicsemi.com/f/nordic-q-a/16034/can-uart-peripherial-activity-wakeup-device-from-sleepDear Sir, I am new in nRF51 and used the ble_app_uart example in our application (nRF51), need power saving function but not necessary power off. The sample code will power off nRF51 as below, and only can wakeup by pressing button. static voiden-USTelligent Community 13Sat, 27 Aug 2016 09:11:19 GMThttps://devzone.nordicsemi.com/thread/61155?ContentTypeID=1Sat, 27 Aug 2016 09:11:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:13169e1b-fa6a-4cf1-84eb-30cda32a022cRK<ol> <li> <p>don&#39;t have any of that power off code, just use sd_app_evt_wait() which will sleep the chip whenever there&#39;s nothing for the CPU to do.</p> </li> <li> <p>If you&#39;re in power-off mode then you will lose any UART data, but if you are just sleeping (sd_app_evt_wait()) then the UART will clock in data and generate an interrupt which will bring you out of sleep mode, as long as you are using interrupts for it.</p> </li> <li> <p>The device only sleeps when you run code which sleep it, ie the power off code you show, or sd_app_evt_wait(), so you already know when you&#39;re sleeping.</p> </li> <li> <p>Don&#39;t really understand what you&#39;re asking here.</p> </li> </ol><div style="clear:both;"></div>