STM32L072KB datasheet(33/147 Pages) STMICROELECTRONICS

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STM32L072xx

Functional overview

3.16.4

SysTick timer

This timer is dedicated to the OS, but could also be used as a standard downcounter. It is

based on a 24-bit downcounter with autoreload capability and a programmable clock

source. It features a maskable system interrupt generation when the counter reaches ‘0’.

3.16.5

Independent watchdog (IWDG)

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

clocked from an independent 37 kHz internal RC and, as it operates independently of 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.

3.16.6

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.

3.17

Communication interfaces

3.17.1

I2C bus

Up to three I2C interfaces (I2C1 and I2C3) can operate in multimaster or slave modes.

Each I2C interface can support Standard mode (Sm, up to 100 kbit/s), Fast mode (Fm, up to

400 kbit/s) and Fast Mode Plus (Fm+, up to 1 Mbit/s) with 20 mA output drive on some I/Os.

7-bit and 10-bit addressing modes, multiple 7-bit slave addresses (2 addresses, 1 with

configurable mask) are also supported as well as programmable analog and digital noise

filters.

In addition, I2C1 and I2C3 provide hardware support for SMBus 2.0 and PMBus 1.1: ARP

capability, Host notify protocol, hardware CRC (PEC) generation/verification, timeouts

verifications and ALERT protocol management. I2C1/I2C3 also have a clock domain

Table 11. 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

Benefits

Available in Stop mode

1. Extra filtering capability vs.

standard requirements.



2. Stable length

Drawbacks

Variations depending on

temperature, voltage, process

Wakeup from Stop on address

match is not available when digital

filter is enabled.

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