PCF8563 datasheet(18/50 Pages) NXP

18 / 50 page

PCF8563

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Product data sheet

Rev. 10 — 3 April 2012

18 of 50

NXP Semiconductors

PCF8563

Real-time clock/calendar

8.8.2 Register Timer

The register Timer is an 8-bit binary countdown timer. It is enabled and disabled via the

Timer_control register bit TE. The source clock for the timer is also selected by the

Timer_control register. Other timer properties such as interrupt generation are controlled

via the register Control_status_2.

For accurate read back of the count down value, it is recommended to read the register

twice and check for consistent results, since it is not possible to freeze the countdown

timer counter during read back.

Table 24.

Timer - timer value register (address 0Fh) bit description

Bit

Symbol

Value

Description

7 to 0

TIMER[7:0]

00h to FFh

countdown period in seconds:

where n is the countdown value

Table 25.

Timer register bits value range

Bit

128

8421

CountdownPeriod

SourceClockFrequency

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PCF8563 Datasheet(PDF) 18 Page - NXP Semiconductors