How to disable APPROTECT permanently? DFU is needed

RE: How to disable APPROTECT permanently? DFU is needed

Hung Bui — Mon, 13 Feb 2023 12:19:42 GMT

The code you provided in your question is actually disabling APPROTECT in the hardware. It's the code that written to UICR to disable APPROTECT.
Please see here: https://infocenter.nordicsemi.com/topic/ps_nrf52840/dif.html?cp=5_0_0_3_7_1#concept_udr_mns_1s
In addition to hardware (write to UICR in flash, this only need to be done once) you need to disable it in firmware (write to APPROTECT.DISABLE in the firmware, this need to be performed on every boot)

RE: How to disable APPROTECT permanently? DFU is needed

TitanDaniel — Mon, 13 Feb 2023 11:37:34 GMT

Hi Hung,

I am now disable it with software only, can you please show me how to disable it on hardware?

Regards,

Daniel

RE: How to disable APPROTECT permanently? DFU is needed

Hung Bui — Mon, 13 Feb 2023 10:16:03 GMT

Hi Daniel,
Thanks for letting us know. Please be aware that with the enchanced APPROTECT from revision 3 of the chip you need to disable APPROTECT in both hardware and software. I would assume the older MDK doesn't have the software disable part enabled.

Note that DFU and the bootloader is not affected by APPROTECT. APPROTECT only disconnects the chip from SWD interface (from the programmer) not the bootloader.