STM32F412XE datasheet(36/201 Pages) STMICROELECTRONICS

36 / 201 page

Functional overview

STM32F412xE/G

36/201

DocID028087 Rev 7

3.23.4

Independent watchdog

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

clocked from an independent 32 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.

3.23.5

Window watchdog

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.

3.23.6

SysTick timer

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

downcounter. It features:

•

A 24-bit downcounter

•

Autoreload capability

•

Maskable system interrupt generation when the counter reaches 0

•

Programmable clock source.

3.24

Inter-integrated circuit interface (I2C)

The devices feature up to four I2C bus interfaces which can operate in multimaster and

slave modes:

•

One I2C interface supports the Standard mode (up to 100 kHz), Fast-mode (up to

400 kHz) modes and Fast-mode plus (up to 1 MHz).

•

Three I2C interfaces support the Standard mode (up to 100 KHz) and the Fast mode

(up to 400 KHz). Their frequency can be increased up to 1 MHz. For more details on

the complete solution, refer to the nearest STMicroelectronics sales office.

All I2C interfaces features 7/10-bit addressing mode and 7-bit addressing mode (as slave)

and embed a hardware CRC generation/verification.

They can be served by DMA and they support SMBus 2.0/PMBus.

The devices also include programmable analog and digital noise filters (see Table 6).

Table 6. Comparison of I2C analog and digital filters

Analog filter

Digital filter

Pulse width of

suppressed spikes

≥ 50 ns

Programmable length from 1 to 15 I2C peripheral clocks

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