Datasheet

PCF2127AT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6 — 11 July 2013 49 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
The pulse generator for the minute/second interrupt operates from an internal 64 Hz clock
and generates a pulse of
1
⁄
64
seconds in duration.
8.13.2 Countdown timer interrupts
The generation of interrupts from the countdown timer is controlled by the CDTIE bit
(register Control_2).
The interrupt may be generated as a pulsed signal at every countdown period or as a
permanently active signal which follows the status of the countdown timer flag CDTF. Bit
TI_TP is used to control this bit.
In this example, bit TI_TP is logic 1 and the MSF flag is not cleared after an interrupt.
Fig 26. INT example for SI and MI when TI_TP is logic 1
In this example, bit TI_TP is logic 0 and the MSF flag is cleared after an interrupt.
Fig 27. INT example for SI and MI when TI_TP is logic 0
001aaf905
58 59 59 00
11
seconds counter
minutes counter
INT when SI enabled
MSF when SI enabled
INT when only MI enabled
MSF when only MI enabled
12
00 01
001aag072
58seconds counter
minutes counter
INT when SI enable
MSF when SI enable
INT when only MI enabled
MSF when only MI enabled
59 59
11
00 00 01
12