STM32F398VE datasheet(24/151 Pages) STMICROELECTRONICS

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Functional overview

STM32F398VE

24/151

DocID027227 Rev 2

3.18.4

Independent watchdog (IWDG)

The independent watchdog is based on a 12-bit downcounter and 8-bit prescaler. It is

clocked from an independent 40 kHz internal RC and as it operates independently from the

main clock, it can operate in Stop and Standby modes. It can be used either as a watchdog

to reset the device when a problem occurs, or as a free running timer for application timeout

management. It is hardware or software configurable through the option bytes. The counter

can be frozen in debug mode.

3.18.5

Window watchdog (WWDG)

The window watchdog is based on a 7-bit downcounter that can be set as free running. It

can be used as a watchdog to reset the device when a problem occurs. It is clocked from

the main clock. It has an early warning interrupt capability and the counter can be frozen in

debug mode.

3.18.6

SysTick timer

This timer is dedicated to real-time operating systems, but could also be used as a standard

down counter. It features:



A 24-bit down counter



Autoreload capability



Maskable system interrupt generation when the counter reaches 0.



Programmable clock source

3.19

Real-time clock (RTC) and backup registers

The RTC and the 16 backup registers are supplied through a switch that takes power from

either the VDD supply when present or the VBAT pin. The backup registers are sixteen 32-bit

registers used to store 64 bytes of user application data when VDD power is not present.

They are not reset by a system or power reset, or when the device wakes up from Standby

mode.

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