W83627DHG Datasheet, PDF (188/268 Pages) Winbond – WINBOND LPC I/O

W83627DHG
16. WATCHDOG TIMER
The WDTO# pin is a multi-function pin with GP50 functions and is configured to the WDTO# function, if
Configuration Register CR[2Dh], bit 0 is set to zero.
The Watchdog Timer of the W83627DHG consists of an 8-bit programmable time-out counter and a
control and status register. The time-out counter ranges from 1 to 255 minutes in the minute mode, or 1
to 255 seconds in the second mode. The units of Watchdog Timer counter are selected at Logical
Device 8, CR[F5h], bit[3]. The time-out value is set at Logical Device 8, CR[F6h]. Writing zero disables
the Watchdog Timer function. Writing any non-zero value to this register causes the counter to load this
value into the Watchdog Timer counter and start counting down.
The W83627DHG outputs a low signal to the WDTO# pin (pin 77) when a time-out event occurs. In
other words, when the value is counted down to zero, the timer stops, and the W83627DHG sets the
WDTO# status bit in Logical Device 8, CR[F7h], bit[4], outputting a low signal to the WDTO# pin(pin 77).
Writing a zero will clear the status bit and the WDTO# pin returns to high. Writing a zero will clear the
status bit. This bit will also be cleared if LRESET# or PWROK# signal is asserted.
Additionally, GP40 (pin 85), GP42 (pin 83), GP44 (pin 81) and GP46 (pin 79) provides an alternative
WDTO# function. This function can be configured by the relative GPIO control register.
Please note that the output type of WDTO# (pin 77) and GP42 (pin 83) is push-pull and that of GP40
(pin 85), GP44 (pin 81) and GP46 (pin 79) is open-drain.
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Publication Release Date: Aug, 22, 2007
Version 1.4