PCA10040 dk flash entire erase after linked to jlink

[lzq597]

I'm developing with PCA10040 DK(3.0.0 2022.10), the IDE is SES for ARM 5.42a.

The app is normal after download the application. After a reset or power off and restart, the program works fine. Once I connect the PCA10040 DK with the J-Link on board to J-Flash or J-Link RTT Viewer, the application is erased.

I found this problem by J-flash. Entire flash is erased to 0xFF. I get this problem whether I use the examples in the SDK or my own program on PCA10040. 

But when I use my own PCB and external J-Link, there is not any problem. I can connect to RTT viewer to check logs any time. The flash is normal.

I'm sure I didn't enable read protection.

[Vidar Berg]

Hello,

This version of the nRF52 DK has revision 3 of the nRF52832 with a hardened readback protection mechanism, see https://nrfconnectdocs.nordicsemi.com/pdf/IN/in_142_v1.1.pdf and it is only nRF5 SDK v17.1.0 that supports this revision out of the box. Perhaps you are you using an older SDK? The jlink tools will prompt you to erase the chip if they detect that AP protection is enabled.

Best regards,

Vidar

[lzq597]

I used nRF5_SDK_16.0.0 and 17.1.0, both have this problem. I try again just now with 17.1.0 example ‘ble_app_uart’, it happen just as I say.

[Vidar Berg]

Before programming the ble_app_uart example from SDK v17.1.0, run "nrfjprog --recover" or "nrfutil device recover" from the command line. This command includes writing 0x5A to UICR.APPROTECT to keep approtect unlocked across resets.

[lzq597]

Thanks Vidar, your method is useful. Does this mean that whenever this problem occurs, I need to do a register rewrite the way you said? Is there a one-time solution to avoid this problem?

[lzq597]

I have another question: how should I avoid this problem if I'm using SDK 16.0.0?

[Vidar Berg]

This is a one time operation as long as you do not erase the UICR section or boot the device without a valid FW. 

lzq597 said:

I have another question: how should I avoid this problem if I'm using SDK 16.0.0?

You must upgrade the MDK as stated in IN-142: https://nrfconnectdocs.nordicsemi.com/pdf/IN/in_142_v1.1.pdf