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 36 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
8.10.5 Register Weekday_alarm
[1] Default value.
8.10.6 Alarm flag
When all enabled comparisons first match, the alarm flag AF (register Control_2) is set.
AF will remain set until cleared by command. Once AF has been cleared, it will only be set
again when the time increments to match the alarm condition once more. For clearing the
flags, see Section 8.11.6
Alarm registers which have their alarm enable bit AE_x at logic 1 are ignored.
Table 34. Weekday_alarm - weekday alarm register (address 0Eh) bit description
Bit Symbol Value Description
7 AE_W 0 weekday alarm is enabled
1
[1]
weekday alarm is disabled
6to3 - - unused
2 to 0 WEEKDAY_ALARM 0 to 6 weekday alarm information
Example where only the minute alarm is used and no other interrupts are enabled.
Fig 20. Alarm flag timing diagram
001aaf903
44
45
45minute alarm
minutes counter
AF
INT when AIE = 1
46