Flash protection with DFU on nrF52832

[Nabil]

Hello, 

I'm using : 

- SDK 11 s132

- nRF52832 

I want to protect my flash against dumping from swd but I'm working also with DFU from our custom app. 

Is it possible to update from DFU when flash is protected with APPROTECT ?

Thank you.

[Nguyen Hoan Hoang]

yes.

[Nabil]

Hello, 

I have tried it but it seem that it doesn't work. After updated the app doesn't start with protection but working very well without protection.

Thank you

[Nguyen Hoan Hoang]

I found that some times I had to DFU it twice for it to work.  I haven't found the problem yet.   DFU the first time didn't work. DFU the second time worked.

[Vidar Berg]

Hello,

APPROTECT prevents external access through the debug interface, but does not affect the CPU's access to memory internally. In other words, it shouldn't affect the DFU process. How are you enabling the readback protection, with the programmer, or from the bootloader/app?

[Vidar Berg]

Nguyen Hoan Hoang, are you using the WD timer in your app? Maybe you are seeing  a WD timeout when it fails?   

[Nabil]

Hello, 

I'm only working with : 

$ nrfjprog --family nrf52 --rbp all 

Is that enough ? I didn't add anything more on the soft. Neither in boot nor in app. 

Thank you very much 

[Vidar Berg]

That should work. Did you reset the board afterwards? E.g., nrfjprog --pinreset.  

[Nabil]

It's working but it seem that it's not working when you make a device Firmware update OTA. 

Is it normal that you have to update twice for the application to work?  

Thank you ? 

[Nguyen Hoan Hoang]

Not normal.  I have that issue too with DFU.  Had to DFU twice for it to work.  Don't know why.  This is with SDK14.2.  

[Vidar Berg]

Agree, this isn't normal. Have you tried to do the same with the pre-compiled bootloader? Steps to test pre-compiled bootloader: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v11.0.0/bledfu_example_running.html?cp=4_0_8_4_3_1_1_0_2#bledfu_example_running_test