Systick Timer; Real-Time Clock (Rtc) And Backup Registers; Inter-Integrated Circuit Interface (I 2 C) - STMicroelectronics STM32F050G6 Manual

Functional overview
3.11.5

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)
3.12

Real-time clock (RTC) and backup registers

The RTC and the 5 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 when the device wakes up from Standby
mode.
The RTC is an independent BCD timer/counter. Its main features are the following:
●
Calendar with subsecond, seconds, minutes, hours (12 or 24 format), week day, date,
month, year, in BCD (binary-coded decimal) format.
● Automatically correction for 28, 29 (leap year), 30, and 31 day of the month.
●
Programmable alarm with wake up from Stop and Standby mode capability.
● On-the-fly correction from 1 to 32767 RTC clock pulses. This can be used to
synchronize it with a master clock.
●
Digital calibration circuit with 1 ppm resolution, to compensate for quartz crystal
inaccuracy.
●
2 anti-tamper detection pins with programmable filter. The MCU can be woken up from
Stop and Standby modes on tamper event detection.
● Timestamp feature which can be used to save the calendar content. This function can
triggered by an event on the timestamp pin, or by a tamper event. The MCU can be
woken up from Stop and Standby modes on timestamp event detection.
The RTC clock sources can be:
●
A 32.768 kHz external crystal
●
A resonator or oscillator
●
The internal low-power RC oscillator (typical frequency of 40 kHz)
● The high-speed external clock divided by 32.
3.13 Inter-integrated circuit interface (I
2
The I C interface (I2C1) can operate in multimaster or slave mode. It can support Standard
mode (up to 100 kbit/s), Fast mode (up to 400 kbit/s) and Fast Mode Plus (up to 1 Mbit/s)
with 20 mA output drive.
It supports 7-bit and 10-bit addressing modes, multiple 7-bit slave addresses (2 addresses,
1 with configurable mask). It also includes programmable analog and digital noise filters.
20/98
pin. The backup registers are five 32-bit
BAT
2
Doc ID 023079 Rev 3
power is not present.
DD
C)
STM32F050xx