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 47 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
8.13 Interrupt output, INT
PCF2127AT has an interrupt output pin INT which is open-drain, active LOW. Interrupts
may be sourced from different places:
• second or minute timer
• countdown timer
When SI, MI, CDTIE, WD_CD, AIE, TSIE, BIE, BLIE are all disabled, INT will remain high-impedance.
Fig 25. Interrupt block diagram
BLF: BATTERY
LOW FLAG
SET
set battery
low flag, BLF
to interface:
read BLF
BLIE
001aag070
from battery
low detection
circuit: clear BF
CLEAR
BF: BATTERY
FLAG
SET
set battery
flag, BF
to interface:
read BF
BIE
from interface:
clear BF
CLEAR
TSFx: TIMESTAMP
FLAG
SET
set timestamp
flag, TSFx
to interface:
read TSFx
TSIE
from interface:
clear TSFx
CLEAR
AF: ALARM
FLAG
SET
set alarm
flag, AF
to interface:
read AF
AIE
from interface:
clear AF
CLEAR
WDTF:
WATCHDOG
TIMER FLAG
SET
WATCHDOG
COUNTER
to interface:
read WDTF
WD_CD[1:0] = 00
WD_CD[1:0] = 01
MCU loading
watchdog counter
CLEAR
CDTF:
COUNTDOWN
TIMER FLAG
SET
COUNTDOWN
COUNTER
to interface:
read CDTF
CDTIE
INT pin
0
1
WD_CD[1:0] = 01
from interface:
clear CDTF
CLEAR
PULSE
GENERATOR 2
TRIGGER
CLEAR
MSF:
MINUTE
SECOND FLAG
SET
MINUTES COUNTER
SECONDS COUNTER
to interface:
read MSF
SI/MI
TI_TP
0
1
from interface:
clear MSF
CLEAR
SI
MI
PULSE
GENERATOR 1
TRIGGER
CLEAR