PCF8563
NXP Semiconductors
Real-time clock/calendar
8.8.2 Register Timer
Table 24. Timer - timer value register (address 0Fh) bit description
Bit
Symbol
Value
Description
countdown period in seconds:
7 to 0
TIMER[7:0]
00h to FFh
n
CountdownPeriod =
--------------------------------------------------------------
SourceClockFrequency
where n is the countdown value
Table 25. Timer register bits value range
Bit
7
6
5
4
3
2
1
0
128
64
32
16
8
4
2
1
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.
PCF8563
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Product data sheet
Rev. 10 — 3 April 2012
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NXP [ NXP ]
