How SD_MBR_COMMAND_COPY_BL works under SD132 7.0.1 when bootloader is protected by BPROT?

[Adam BZH]

Currently our product shipped with SD132 7.0.1, and bootloader/dfu compiled with SDK 16.0.0

We are testing update the bootloader on production devices, and want know how the process actually works

From arm's document, once BPROT is set, the only way to clear it is to reset the device, so how the SD/MBR manage to replace the bootloader under BPROT protect?

Is SD/MBR changing reset vector before reset the chip to clear BPROT? then continue on with the BL replacement?

From my testing, the process is successful, but we would like to make sure there is no other things to worry about before rolling out.

[Einar Thorsrud]

Hi,

As you write, BPROT is disabled at reset. And the MBR runs immediately after reset, before jumping to the bootloader (which then enabled BPROT).

(To initiate a bootloader update the bootloader writes relevant parameters to the MBR params page before reset, and this is always checked by the MBR at startup).