https://devzone.nordicsemi.com/f/nordic-q-a/112776/acl-peripheral-cannot-be-used-in-main-processingHello. I am trying to write protect the Flash area using nrf52840&#39;s ACL peripheral. I tried to perform the same process on the main processing side by referring to nrf_bootloader_flash_protect() in nrf_bootloader_app_start_final.c, but an exceptionen-USTelligent Community 13Mon, 08 Jul 2024 04:09:00 GMThttps://devzone.nordicsemi.com/thread/492590?ContentTypeID=1Mon, 08 Jul 2024 04:09:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:fa1f24aa-baf4-44f1-959d-07727a9f2857Rockedge<pre id="tw-target-text" class="tw-data-text tw-text-large tw-ta" dir="ltr" data-ved="2ahUKEwiIkPDayJaHAxVVh68BHWFIBN4Q3ewLegQIBRAU"><span class="Y2IQFc" lang="en">Hello Vidar Berg. Thank you for your reply. I understand that access to the ACL register is restricted while SoftDevice is running. That&#39;s right, SoftDevice was working. Also, after checking the SoftDevice manual, I found that it is possible to write to the ACL register using sd_protected_register_write(). Thank you very much.</span></pre><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/492422?ContentTypeID=1Fri, 05 Jul 2024 10:49:56 GMT137ad170-7792-4731-bb38-c0d22fbe4515:dc24f7f4-6cfd-4445-80b5-4cd874ca377bVidar Berg<p>Hello,&nbsp;</p> <p>It should not be a problem to use the ACL while running the main app, but it is important to note that you can&#39;t access this peripheral directly while the Softdevice is enabled .</p> <p><img style="max-height:240px;max-width:320px;" src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/pastedimage1720176510293v1.png" alt=" " /></p> <p>Ref.&nbsp;<a href="https://docs.nordicsemi.com/bundle/sds_s140/page/SDS/s1xx/sd_resource_reqs/hw_block_interrupt_vector.html">Softdevice reserved peripherals</a></p> <p>What kind of exception did you get when you tried to configured the ACL in your app?</p> <p>Best regards.</p> <p>Vidar</p><div style="clear:both;"></div>