Register Protection of SPC560Dxx

[Central SUPPORT]

I do not quite understand paragraph 29.3 "Modes of operation" of RM0045 Reference Manual for SPC 56D Line MCUs. It says:

1. Can my firmware change the protection dynamically, i.e. protect resp. unprotect registers?
2. Is there any register that can get the source of reset?

                                                

NOTE: This question and answer originated from a customer support case which was handled by us. We regularly review support cases and add any helpful ones here for all to benefit from.

[Central SUPPORT]

1) You should activate the register protection of the safety related registers.

There are 2 possibilities to protect the registers either with hard or soft lock protection:

• if a register is protected by the "hard lock", only a reset can remove the lock
• if a register is protected by the "soft lock", the software can remove the lock.

From the safety standpoint, the hard lock is a better choice because even if the software "gets crazy" it can't remove the lock.

2) Yes, the user can read the source of the last reset by looking at the status registers of the RGM, FES and DES.