How to use J-link to encrypt nRF51422?

[Charleslee]

Hi guys First of all, I know nRFgo can be very convenient for application encryption, but in order to improve the mass production efficiency,I merged the application code with softdevice then load the merged hex file by J-flash

The question is, how the j-link achieve readback protection without modifying software(Because our customers have confirmed the software)?

Our local Nordic FAE provides a method by setting j-flash as follows: 0x0003C000 is the starting address of application

But a bug has occured! When using this setting load hex file ： condition one：if I connect directly with the nRFgo after loading hex file, I still can read the code;condition two：if I try to read application code by j-flash after loading hex file immediately，the readback protection come into effect ，then connect with nRFgo ，readback protection Is also valid so I got very confused

[Susheel Nuguru]

You can use nrfjprog --rpb option

 --rbp <level>           Enables the readback protection mechanism. Valid
                         argument options are CR0 and ALL.
                         Limitations:
                         For nRF52 devices, the CR0 argument option is
                         invalid.
                         Side effects:
                         After an --rbp operation is performed, the
                         available operations are reduced.
                         For nRF51 devices, and if argument option ALL is
                         used, --pinreset will not work on certain older
                         devices.
                         For nRF52 devices, only --pinreset, --debugreset
                         or --recover operations are available after --rbp.

[testy]

Add "Reset" to the "Exit steps", then perform Target\Auto as stated in the J-Flash User Guide. The address 0x10001000/step #2/ looks strange - 0x10001014 should be better...