https://devzone.nordicsemi.com/f/nordic-q-a/886/readback-register-and-securityOn the nRF51822, I see that by programming the readback protect register, one can prevent reading code regions 0 and 1 from the SWD interface. However, if one had access to the SWD interface, a debugger, and the nrfjprog tool, it appears that the UICRen-USTelligent Community 13Fri, 15 Nov 2013 11:45:15 GMThttps://devzone.nordicsemi.com/thread/4337?ContentTypeID=1Fri, 15 Nov 2013 11:45:15 GMT137ad170-7792-4731-bb38-c0d22fbe4515:876bc418-0d2b-4199-b7d9-d64196a3cd4fOle Morten<p>As far as I know, enabling read-back protection should give the full protection you&#39;re after. The ERASEUICR register is not available on an nRF51822, since it doesn&#39;t have any pre-programmed code, as shown in table 4 in the nRF51822 Reference Manual, and hence there should be no way of getting access to code on an nRF51822 if read-back protection has been set. The only way to disable protection would be to do an erase-all, in which case the protected code would also be gone.</p><div style="clear:both;"></div>