AN3133 datasheet(18/43 Pages) STMICROELECTRONICS

Part #	AN3133

Description	A real-time clock is a computer clock that keeps track of the current time

PDF	43 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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Programming the RTC

AN3133

18/43

Doc ID 16956 Rev 5

2.3

Programming the Auto-wakeup unit

Table 6 describes the steps required to configure the Auto-wakeup unit.

Table 6.

Steps to configure the Auto wake-up unit

Step

What to do

How to do it

Comments

Disable the wakeup timer.

Clear WUTE bit in

RTC_CR2 register.

Ensure access to Wakeup auto-reload

counter and bits WUCKSEL[2:0] is allowed.

Poll WUTWF until it

is set in RTC_ISR1.

It takes approximately 2

RTCCLK clock cycles.

Program the value into the wakeup timer.

Set RTC_WUTRL

and RTC_WUTRH.

See Section 3.4:

Maximum and minimum

RTC wakeup period.

Select the desired clock source.

Program

WUCKSEL[2:0] bits

in RTC_CR1 register.

Re-enable the wakeup timer.

Set WUTE bit in

RTC_CR2 register.

The wakeup timer

restarts down-counting.

AN3133 Datasheet(PDF) 18 Page - STMicroelectronics