S08 - does the backdoor key enable erase and write access to block protected sectors?

[jhaee]

hi,
I have been reading the reference manual and a lot of post on this forum, however it is still very unclear to me if the backdoor key only unlocks the read secured FLASH or if it also unlocks the block protected flash. Enabling erase and reprogramming of the top sectors.

If the backdoor key does not unlock the block protect? Is there another way to do this from the application?

The scenario for which I potential need this feature is this: we have a product (HCS08GT60 based) with a functional bootloader, this bootloader is block protected and takes 2kB of the code space. However due to increasing demand for functionality, the application needs more space. To meet the demand we are considering if it is possible to change the bootloader to a version based on the an2295. For this to work it would be necessary to be able to load an application that could unlock the protected flash and erase it and load a new bootloader and a new size for the protected sectors.

[peg]

Hi,

Using the backdoor to gain access to a secure device, temporarily bypasses security only!

Block protection is a completely seperate thing.

[jhaee]

hi peg,

Thanks for the clarity about the backdoor key.

just to confirm : then there Is no way to get around the block protect from the application?

[peg]

Hi jhaee,

That is correct you can only write to the FPROT register from the BDM.

So once you have enabled any amount of protection by programming NVPROT, you have protected NVPROT so you can no longer modify it here. Then only the BDM can modify FPROT so you are correct that from your code you can not bypass any level of block protection.