DS1386/1386P

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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 zero. When

zero 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 are 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 countdown register is internal and is not

readable. Writing registers C and D to 0 will disable the watchdog alarm feature.