Problems updating a read protected device via DFU

[Roger Clark]

On a nRF52832... I'm trying to create a DFU package to update an existing SDK 11 SD2.0.0 firmware, to update it to SDK 12 SD + new application + secure bootloader But the existing firmware is as appprotect set and the DFU seems to fail somehow

It is possible for single bank DFU to replace the SD + BL + application (in SDK 11) to SDK 12, if read protected?

Its hard to debug what's going on, because our existing installation, is read protected, so I can't simply read back the flash to see what the DFU bootloader has managed to update.

I guess I could put in some code to output messages via UART, but before I start, I thought I'd check whether there is some fundamental reason why this is not possible ?

Edit. Its protected using nrfjprog --rbp ALL

I thought this just did readback protection, or does it also lock the flash somehow

(We have done application updates in the past via DFU, and they worked OK, but not SD + BL updates)

[bjorn-spockeli]

Hi Roger,

you are correct, the nrfjprog --pbp only disconnects the Access Port to prevent the CPU registers and memory-mapped addresses from being read back and does not lock the flash. The BPROT peripheral can be used to prevent application code from erasing or writing to protected blocks. However, the block protection is by default not enabled and you need to explicitly enabled it in code. So If you have not enabled this, then you should not have any issues performing an update of the SD+APP+BL.

Best regards

Bjørn

[Roger Clark]

Thanks Bjørn

I'll check the original source code to see if the programmer who wrote it used BPROT.