65.5.6 Operating Modes

The SECUMOD is supplied by the VDDBU power supply. It is not possible to program the SECUMOD if VDDBU is not present.

The SECUMOD macrocell is able to operate in two different modes:

  • When all supplies are present and can be monitored, the SECUMOD can be switched to Normal mode.
  • Otherwise, the SECUMOD must be in Backup mode.
Note: After a powerup reset, the SECUMOD is in Backup mode.

The mode is selected by setting either SECUMOD_CR.NORMAL or SECUMOD_CR.BACKUP.

Note: The user must set SECUMOD_CR.BACKUP to enter Backup mode prior to shutting off the VDDCORE power supplies.

In both modes, the user can enable or disable a protection by writing in the corresponding Mode Protection register. See Activation or Deactivation of Protections for more information.