DS1486 Datasheet, PDF (6/17 Pages) Dallas Semiconductor – RAMified Watchdog Timekeeper

DS1486/DS1486P
WATCHDOG ALARM REGISTERS
Registers C and D contain the time for the Watchdog Alarm. The two registers contain a time count from
00.01 to 99.99 seconds in BCD. The value written into the Watchdog Alarm Registers can be written or
read in any order. Any access to Register C or D will cause the Watchdog Alarm to reinitialize and clears
the Watchdog Flag bit and the Watchdog Interrupt Output. When a new value is entered or the Watchdog
Registers are read, the Watchdog Timer will start counting down from the entered value to 0. When 0 is
reached, the Watchdog Interrupt Output will go to the active state. The Watchdog Timer Countdown is
interrupted and reinitialized back to the entered value every time either of the registers is accessed. In this
manner, controlled periodic accesses to the Watchdog Timer can prevent the Watchdog Alarm from
going to an active level. If access does not occur, countdown alarm will be repetitive. The Watchdog
Alarm Registers always read the entered value. The actual count-down register is internal and is not
readable. Writing registers C and D to 0 will disable the Watchdog Alarm feature.
DS1486 RAMIFIED TIMEKEEPER REGISTERS Figure 2
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