Softdevice protection and nordic DFU

[AlwinG]

Hi.

I have built an ble application which runs on the nrf52832 with softdevice S132 V 6.0.0.
In addition to the application and the softdevice I program a bootloader on the device.
So I'm able to use the nordic DFU!

When programming the device I can choose following options:

- Lock Softdevice from readback

- Enable Softdevice protection

- Lock entire chip from readback

Does one of these options affect the funtion of the nordic DFU?

Thanks.

Alwin

[Vidar Berg]

Hi Alwin, 

The first two options you listed should not be available on the nRF52 series. The Softdevice is secured with the MWU peripheral, which cannot be disabled with a programming flag (Maybe you are using nRFgo studio for programming?). On the 52 series, you can lock the entire chip from readback. Readback protection will not impact DFU as it is only the Debug interface that gets disabled.  

[AlwinG]

Hi Vidar,

Thanks for answering!

Yes I use nRFgo studio to load the images.

There I can check or uncheck these options (Lock SD from readback, enable SD protection, lock chip from readback).

Do they have no effect?

[Vidar Berg]

Hi, these checkboxes are greyed out in my version of nRFGo studio (1.21.2.10). In any case, these options should not be enabled when programming 52 series, nor should they have been displayed.  nRFGo studio has been replaced by the programmer app in nRF connect for desktop.

[AlwinG]

Hi.

Now I tested it with the nRF connect app "Programmer" (V 2.6.2) and read the migration document (nrf51 to nrf52).

As you said the CLENR0 is not available on the nrf51 and the new MWU protects the softdevice.

To enable read-back I have to use the APPROTECT.

... is that correct?

According to application notes and devzone I can set the APPROTECT  in FW. But how can i set this read-back with nRF connect?

If I set the read-back in nRFgo Studio, I can't read it with nRFconnect and I found no option to recover the nRF52!

[Vidar Berg]

Hi,

Correct, you can enable readback protection by writing to the APPROTECT register in UICR.  Unfortunately, enabling and disabling of readback protection does not seem to be supported in nRF connect yet. Do you have nrfjprog installed? The following commands are used to enable/disable readback protection:

nrfjprog --rbp all // enables readback protection by writing to UICR.APPROTECT

nrfjprog --recover // Performs a full chip erase to disable readback protection

[AlwinG]

Hi Vidar.

Yes I have nrfjprog installed.

Thanks for answering!