PCF8583
NXP Semiconductors
Clock and calendar with 240 x 8-bit RAM
MUX
mode
oscillator
select
CLOCK/CALENDAR
counter
control
ALARM
TIMER
clock
alarm
alarm
control alarm
timer
timer
control
overflow
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
ALARM CONTROL
REGISTER
CONTROL/STATUS
REGISTER (1)
timer overflow
interrupt
alarm
interrupt
INT
013aaa377
(1) If the alarm enable bit of the control and status register is reset (logic 0), a 1 Hz signal is observed on the interrupt pin INT.
Fig 12. Alarm and timer interrupt logic diagram
7.8 Event counter mode
Event counter mode is selected by bits 4 and 5 which are logic 10 in the control and status
register. The event counter mode is used to count pulses externally applied to the
oscillator input (OSCO left open-circuit).
The event counter stores up to 6 digits of data, which are stored as 6 hexadecimal values
located in the registers 1h, 2h, and 3h. Therefore, up to 1 million events may be recorded.
An event counter alarm occurs when the event counter registers match the value
programmed in the registers 9h, Ah, and Bh, and the event alarm is enabled (bits 4 and 5
which are logic 01 in the alarm control register). In this event, the alarm flag (bit 1 of the
control and status register) is set. The inverted value of this flag can be transferred to the
interrupt pin (pin 7) by setting the alarm interrupt enable in the alarm control register. In
PCF8583
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© NXP B.V. 2010. All rights reserved.
Product data sheet
Rev. 06 — 6 October 2010
12 of 37
NXP [ NXP ]
