https://devzone.nordicsemi.com/f/nordic-q-a/79358/is-it-possible-to-check-if-a-kmu-slot-is-usedHello, I am using NCS v1.5.0 and would like to check is a KMU slot is being used or not. I erased the whole SoC and tried reading the directly the registers, in secure mode, as follows: but the value is always 0xdeaddead. The same value is readen-USTelligent Community 13Thu, 09 Sep 2021 17:29:51 GMThttps://devzone.nordicsemi.com/thread/328885?ContentTypeID=1Thu, 09 Sep 2021 17:29:51 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b1274517-8161-469a-a6e6-6f59eeb44c6eHakon<p>Hello,</p> <p></p> [quote user=""]but the value is always 0xdeaddead.[/quote] <p>From the KMU documentation;</p> <p>&quot;Step 2 will be blocked and word 0xDEADDEAD will be returned on AHB if any of the following violations are detected:</p> <ul> <li>No key slot selected</li> <li>Key slot not configured as readable</li> <li>Key slot is revoked</li> <li>AHB read to KEYSLOT.KEY[ID-1].VALUE[0-3] registers not belonging to selected key slot&quot;</li> </ul> <p>&nbsp;</p> <p>&nbsp;</p> [quote user=""]Is it possible to check if a KMU slot&nbsp;is in use ?&nbsp;[/quote] <p>&nbsp;I&#39;m not aware of any ways to check this, but you can look at <a href="https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf9160%2Fkmu.html&amp;cp=2_0_0_5_7">this</a> and <a href="https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf9160%2Fuicr.html&amp;cp=2_0_0_3_5_0_8&amp;anchor=register.KEYSLOT.CONFIG.PERM">this</a> and see if there are any registers you can use for that.</p><div style="clear:both;"></div>