21.1.2 Register Write Protection

To prevent any single software error from modifying the configuration of the Reset Controller (RSTC), Shutdown Controller (SHDWC), Real-time Timer (RTT), Slow Clock Controller (SCKC), General Purpose Backup Register (GPBR), Real-time Clock (RTC) and Watchdog Timer (WDT), some registers of these peripherals can be write-protected by setting the WPEN and/or WPITEN bits in the System Controller Write Protection Mode register (SYSC_WPMR).

Note: The WDT embeds additional write protection mechanisms.

When write protection is enabled, any attempt to write these registers is reported in the System Controller Write Protection Status register (SYSC_WPSR).

The following registers can be write-protected when SYSC_WPMR.WPEN=1:

  • RSTC Mode Register
  • SHDWC Mode Register
  • SHDWC Wakeup Inputs Register
  • SCKC Configuration Register
  • RTC Control Register
  • RTC Mode Register
  • RTC Time Alarm Register
  • RTC Calendar Alarm Register
  • RTT Mode Register
  • RTT Alarm Register
  • RTT Modulo Selection Register
  • GPBR Full Clear Register
  • GPBR Registers

The following registers can be write-protected when SYSC_WPMR.WPITEN=1:

  • RTC Interrupt Enable Register
  • RTC Interrupt Disable Register