https://devzone.nordicsemi.com/f/nordic-q-a/67978/bmd-350-not-waking-up-from-system-off-mode-even-after-accelerometer-interruptHi all, We have designed a PCB where we use BMD-350 ( which is based on nrf52832 ) , HX711 and the accelerometer ( MMA8452Q ) as primary components. The device is supposed to stay in a deep sleep mode and wake up only when the accelerometer detectsen-USTelligent Community 13Thu, 05 Nov 2020 14:16:35 GMThttps://devzone.nordicsemi.com/thread/278628?ContentTypeID=1Thu, 05 Nov 2020 14:16:35 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c4573881-d05b-4f48-b3bc-3ba37282f1b2Karl Ylvisaker<p>Hello,</p> [quote user=""]Though we have tested the code with sd_app_event_wait () and it works fine, we wanted to test the deepest sleep mode i.e. System off mode of BLE.[/quote] <p>It sounds like you are on the right path here, but I suspect a slight modification to your code is necessary to achieve this. The pin needs to be configured as a specific wakeup pin before going to SYSTEM OFF, while as waking from sd_app_evt_wait ( SYSTEM ON ) only requires an event.<br /><br />This is demonstrated in a lot of the BLE peripheral examples in the SDK, and I highly recommend that you take a look at how it is implemented there.<br />For example, you could take a look at the <em>sleep_mode_enter</em> function of <a href="https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/ble_sdk_app_hids_keyboard.html">the BLE Peripheral HID Keyboard example from the SDK v.17.0.2</a>.<br />This functions is called to put the device in SYSTEM OFF, and prepares it for wakeup as the last thing it does before going to SYSTEM OFF.<br /><br />Please do not hesitate to let me know if anything should still be unclear, or if you have any questions related to this.<br /><br />Best regards,<br />Karl</p><div style="clear:both;"></div>