ADLINK Technology NuPRO-720, Руководство пользователя

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Watch Dog Timer 47
NuPRO-720
4 Watch Dog Timer
NuPRO-720 implements a watch dog timer (WDT) embedded in
the LPC based Winbond 83627HG Super I/O controller.
The Watchdog timer consists of a one-second/minute resolution
counter (CRF6 on logical device 8 of 83627HG) and two watch
dog control registers (CRF5 and CRF7 on logical device 8). Once
a value is set in the WDT, the timer begins to count down.
Any movement in the keyboard, mouse, or software reset of the
value will cause a reload of the timer value. The Watchdog output
is connected to “reset”. If the system hangs without a software re-
trigger, the system will be reset.
The watch dog timer has a one second granularity up to 255 sec-
onds or a one minute granularity up to 255 minutes. The keyboard
and mouse will only reset the WDT if Bit 7 and 6 of CRF7 is set;
that is values greater than C0h or 192 decimal.
To configure the registers and set up the watch dog timer, the fol-
lowing sequence should be followed:
X Write 87h to location 2Eh twice to enter extended function
mode
X Configure the registers to set up the WDT
X Write 0AAh to location 2Eh to exit the extended function
mode