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 39 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
Remark: WDTF is read only and cannot be cleared by command. WDTF can be cleared
by:
• loading a value in register Watchdg_tim_val
• reading of the register Control_2
Writing a logic 0 or logic 1 to WDTF has no effect.
• When the watchdog timer counter reaches 1, the watchdog timer flag WDTF is set
logic 1
• When a minute or second interrupt occurs, the minute/second flag MSF is set logic 1
(see Section 8.13.1
)
Counter reached 1, WDTF is set logic 1, and an interrupt is generated.
Fig 21. WD_CD[1:0] = 10: watchdog activates an interrupt when timed out
Counter reached 1, WDTF is set logic 1, reset pulse on the RST pin is generated for a time equal
to t
w(rst)
.
Fig 22. WD_CD[1:0] = 11: watchdog activates a reset pulse when timed out
001aag062
watchdog
timer value
WDTF
n = 1 n
MCU
INT
001aag063
watchdog
timer value
WDTF
t
w(rst)
n = 1 n
MCU
RST