Datasheet

PCF8563 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
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
7 6 5 4 3 2 1 0
1286432168421
CountdownPeriod
n
SourceClockFrequency
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