What does "Lock entire chip from readback" do at nRFgo Studio?

[MANGO]

Hi, I use the nRFgo Studio to download the softdevice.

Recently I learned how to convert a hex file when I work with IAR.

So I tried my hex file with the nRFgo Studio.

Anyways, there was one curious thing.

What does "Lock entire chip from readback" do?

-Regards, Mango922

[endnode]

This settings causes write to UICR.RBCONF register at the end of programming which locks the chip from flash read-back. This is highly advised for devices going out of production to the field otherwise anyone equipped with JTAG/SWD programmer could read your entire firmware from flash, dis-assemble it etc...

You do not need to worry during development and you can even check this because RB protection is not permanent. It only forces full NVM erase if you want to program it but you can do it again. It also does not prevent FW itself to re-write flash internally (and if you set-up registers correctly you can rewrite basically whole flash - e.g. by using MBR routines from bottom 4kB of the Soft Device).

As far as I know there is no hard lock which would lock programming interface forever so theoretically your HW will be always vulnerable to attackers with SWD programmers because they can erase them and potentially re-program. However this requires physical access to the device and you can damage it usually by easier way.

You can see details of UICR and other settings in Nordic's Reference Manual (v3.0 - chapter 8).