PCF2123_09 Datasheet, PDF (26/55 Pages) NXP Semiconductors – SPI Real time clock/calendar

NXP Semiconductors
PCF2123
SPI Real time clock/calendar
countdown counter 01
n
CDTF
INT
SCL
instruction
(1)
8th clock
CLEAR INSTRUCTION
001aaf909
(1) Indicates normal duration of INT pulse (bit TI_TP = 1).
Fig 19. Example of shortening the INT pulse by clearing the TF flag
The timing shown for clearing bit TF in Figure 19 is also valid for the non-pulsed interrupt
mode, i.e., when bit TI_TP = 0; INT may be shortened by setting bit TIE to logic 0.
9.9.3 Alarm interrupts
The generation of interrupts from the alarm function is controlled via bit AIE (see Table 6).
If bit AIE is enabled, the INT pin follows the condition of bit AF. Clearing bit AF will
immediately clear INT. No pulse generation is possible for alarm interrupts (see
Figure 20).
minute counter 44 45
minute alarm 45
AF
INT
SCL
instruction
8th clock
CLEAR INSTRUCTION
001aaf910
Example where only the minute alarm is used and no other interrupts are enabled.
Fig 20. AF timing
9.9.3.1 Correction pulse interrupts
Interrupt pulses generated by correction events can be shortened by writing logic 1 to bit
CIE in register Control_1.
PCF2123_2
Product data sheet
Rev. 02 — 4 December 2009
© NXP B.V. 2009. All rights reserved.
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