PCF212311 데이터 시트보기 (PDF) - NXP Semiconductors.
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PCF212311 Datasheet PDF : 63 Pages
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NXP Semiconductors
PCF2123
SPI Real time clock/calendar
8.6 Timer functions
The countdown timer has four selectable source clocks allowing for countdown periods in
the range from 244 μs to 4 h 15 min. There are also two pre-defined timers which can be
used to generate an interrupt once per second or once per minute. For periods greater
than 4 hours, the alarm function can be used. Registers 01h, 0Eh and 0Fh are used to
control the timer function and output.
8.6.1 Register Timer_clkout
Table 24. Timer_clkout - timer control register (address 0Eh) bit description
Bit Symbol
Value
Description
Reference
7
-
-
unused
-
6 to 4 COF[2:0]
[1]
CLKOUT control
Section 8.8
3
TE
0
countdown timer is disabled
Section 8.6.4
1
countdown timer is enabled
2
-
-
unused
1 to 0 CTD[1:0]
00
4.096 kHz countdown timer source clock
01
64 Hz countdown timer source clock
10
1 Hz countdown timer source clock
11[2]
1⁄60 Hz countdown timer source clock
[1] Values of COF[2:0] see Table 35.
[2] Default value.
8.6.2 Register Countdown_timer
Table 25. Countdown_timer - countdown timer register (address 0Ah) bit description
Bit Symbol
Value
Description
7 to 0 COUNTDOWN_TIMER[7:0] 0h to FFh countdown period in seconds:
CountdownPeriod = -------------------------------n-------------------------------
SourceClockFrequency
where n is the countdown value
Reference
Section 8.6.4
8.6.3 Minute and second interrupt
The minute and second interrupts (bits MI and SI) are pre-defined timers for generating
periodic interrupts. The timers can be enabled independently from one another. However,
a minute interrupt enabled on top of a second interrupt will not be distinguishable since it
will occur at the same time; see Figure 14.
PCF2123
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 5 — 27 April 2011
© NXP B.V. 2011. All rights reserved.
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