Independent Watchdog (Iwdg); System Window Watchdog (Wwdg); Systick Timer; Real-Time Clock (Rtc) And Backup Registers - STMicroelectronics STM32F042F4 Manual

STM32F042x4 STM32F042x6
TIM16 and TIM17 have a complementary output with dead-time generation and
independent DMA request generation.
Their counters can be frozen in debug mode.
3.12.3

Independent watchdog (IWDG)

The independent watchdog is based on an 8-bit prescaler and 12-bit downcounter with
user-defined refresh window. 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.
3.12.4

System window watchdog (WWDG)

The system 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 APB clock (PCLK). It has an early warning interrupt capability and the
counter can be frozen in debug mode.
3.12.5

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 (HCLK or HCLK/8)
3.13

Real-time clock (RTC) and backup registers

The RTC and the five backup registers are supplied through a switch that takes power either
on V supply when present or through the V
DD
registers used to store 20 bytes of user application data when V
They are not reset by a system or power reset, or at wake up from Standby mode.
pin. The backup registers are five 32-bit
BAT
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Functional overview
power is not present.
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