PCF2123BS/1 NXP Semiconductors, PCF2123BS/1 Datasheet - Page 20

• Manufacturer Part Number: PCF2123BS/1
• Manufacturer: NXP Semiconductors

Specifications of PCF2123BS/1

• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
Table 25.
PCF2123
Product data sheet
Bit
7 to 0
Symbol
COUNTDOWN_TIMER[7:0]
Countdown_timer - countdown timer register (address 0Ah) bit description
8.6.1 Register Timer_clkout
8.6.2 Register Countdown_timer
8.6.3 Minute and second interrupt
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.
Table 24.
[1]
[2]
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
Bit
7
6 to 4 COF[2:0]
3
2
1 to 0 CTD[1:0]
Values of COF[2:0] see
Default value.
Symbol
-
TE
-
Timer_clkout - timer control register (address 0Eh) bit description
Value
0h to FFh
All information provided in this document is subject to legal disclaimers.
Table
Rev. 5 — 27 April 2011
Value
-
[1]
0
1
-
00
01
10
11
[2]
Description
countdown period in seconds:
where n is the countdown value
CountdownPeriod
35.
Figure
Description
unused
CLKOUT control
countdown timer is disabled
countdown timer is enabled
unused
4.096 kHz countdown timer source clock
64 Hz countdown timer source clock
1 Hz countdown timer source clock
1
⁄
60
14.
Hz countdown timer source clock
=
-------------------------------------------------------------- -
SourceClockFrequency
n
SPI Real time clock/calendar
PCF2123
© NXP B.V. 2011. All rights reserved.
Reference
Section 8.6.4
Reference
-
Section 8.8
Section 8.6.4
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