Program and Erase protection of Flash sectors

[pederrogo]

Hello,

We are using the MPC5744P and would like to somehow protect a flash sector so that it cannot be erased. For example the 256K flash sector starting at address 0x01100000.

While running in the boot SW it should be possible to erase and program the sector, but once entering the Application SW we would like to have the protection enabled.

We know about the Lock registers, e.g. C55FMC_LOCK2 and C55FMC_LOCK3. But, how to protect so that these registers are not writeable?

Best Regards,

Peder Rogö

[petervlna]

Hi,

The lock registers (C55FMC_LOCKn) are not protected by register protection.

But a value of 1 in a bit of the lock register signifies that the corresponding block is locked for program and
erase.

So even if the unlock is done via unintentionally you still have to execute program /erase in order to change the flash content.

The probability of this is extremely low.

If you want to secure this even more you can periodically check C55FMC_LOCKn register content by SW.

regards,

Peter