https://devzone.nordicsemi.com/f/nordic-q-a/1130/why-the-reset-flags-are-the-samewhen I enter the system off mode then used a GPIO to wake up the IC, the &quot;RESETREAS&quot; register show &quot;Reset due to wake-up from OFF mode when wakeup is triggered from the DETECT signal from GPIO&quot;. But when I cut off the power of IC, then connect theen-USTelligent Community 13Mon, 16 Dec 2013 10:12:01 GMThttps://devzone.nordicsemi.com/thread/5278?ContentTypeID=1Mon, 16 Dec 2013 10:12:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5cd420a4-8732-4c21-90c9-3a5e56d1a11dOle Morten<p>Unfortunately, there is an issue with the RESETREAS on revision CA/C0 of the chip, which is documented in <a href="https://www.nordicsemi.com/eng/content/download/29490/494569/file/nRF51822-PAN%20v2.0.pdf">the PAN</a>. The suggested workaround is to write to the GPREGRET register before entering system off, and then check this value to know whether it was a power-on-reset or a wake from off.</p><div style="clear:both;"></div>