pcf8564a NXP Semiconductors, pcf8564a Datasheet - Page 15

• Manufacturer Part Number: pcf8564a
• Description: Real Time Clock And Calendar
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF8564A_1
Product data sheet
8.7 Register CLKOUT_ctrl and clock output
The generation of interrupts from the alarm function is controlled via bit AIE. If bit AIE is
enabled, the INT pin follows the condition of bit AF. AF will remain set until cleared by the
interface. Once AF has been cleared it will only be set again when the time increments to
match the alarm condition once more. Alarm registers which have their AE_x bit at logic 1
are ignored.
A programmable square wave is available at pin CLKOUT. Operation is controlled by the
FE bit in register CLKOUT_ctrl at address 0Dh and the CLKOUT output enable pin
(CLKOE). To enable pin CLKOUT pin CLKOE must be set HIGH.
Frequencies of 32.768 kHz (default), 1.024 kHz, 32 Hz and 1 Hz can be generated for use
as a system clock, microcontroller clock, input to a charge pump, or for calibration of the
oscillator.
Fig 8.
(1) Only when all enabled alarm settings are matching.
It’s only on increment to a matched case that the alarm flag is set, see
Alarm function block diagram
check now signal
WEEKDAY ALARM
MINUTE ALARM
WEEKDAY TIME
HOUR ALARM
MINUTE TIME
DAY ALARM
HOUR TIME
DAY TIME
Rev. 1 — 8 October 2009
=
=
=
=
AE_W
AE_M
AE_H
AE_D
set alarm flag, AF
Real time clock and calendar
AE_M= 1
example
013aaa088
Section
PCF8564A
1
0
(1)
© NXP B.V. 2009. All rights reserved.
8.6.5.
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