I use JLinkExe with a script to read the UICR of a nRF51422 processor. When the processor is secured, the UICR can still be read and can contain useful user information. Now with JLink version 6 the processor is automatic unsecured, which means a mass erase and so also the UICR information is lost. We use the UICR for a unique identifier and hardware information.
With Windows there should be a possibility to hook JLINK_SYS_UnsecureDialog() and block the mass erase. We use Linux for our development environment and this function is not available. How can I block the automatic unsecure function for Linux and use JLinkExe to read the UICR of the nRF51422? Should we go back to version 4 or is there another solution?

kind regards, Erik Postma

Hello Nino,

With the nRF51422 it is possible to block reading the device with the first part of the UICR. The first register in the UICR is CLENR0, which divides the flash in two regions. The fiirst region is mostly used for a softdevice like BLE or ANT. The next register is RBPCONF. it contains two values (PR0 and PALL). By writing 0 in these values reading back the flash is protected. This method I use for securing my code.

Is it not possible to make a JLink version, that just reports that the processor is secured and mentions the availability of the unsecure command? A user can type unsecure him/herself. With version 4 of JLink there was no automatic unsecure process.

Kind regards, Erik Postma