ADLINK Technology CT-61, User Manual

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Utilities 33
CT-61
7 Utilities
7.1 Watchdog Timer
This section describes the operation of the CT-61’s watchdog
timer (WDT). The primary function of the WDT is to monitor the
CT-61's operation and to reset the system if a software application
fails to function as programmed. The following WDT functions may
be controlled using a software application:
X enabling and disabling
X
reloading timeout value
The CT-61 custom WDT circuit is implemented using the internal
IO of the ITE Super I/O IT8783 which is at address 2Eh of LPC.
The basic functions of the WDT include:
X
Starting the timer countdown
X
Enabling or disabling WDT
X
Enabling or disabling WDT countdown LED ON
X Reloading the timeout value to keep the watchdog from timing
out
X Setting the range of the timeout period from 1 to 15300 seconds
or minutes
X Sending a RESET signal to the system when the watchdog
times out
Using the Watchdog in an Application
The following section describes using the WDT functions in an
application. The WDT reset function is explained in the previous
section. This can be controlled through the registers in the CT-61's
Super I/O.
An application using the reset feature enables the watchdog func-
tion, sets the count-down period, and reloads the timeout value
periodically to keep it from resetting the system. If the timer count-
down value is not reloaded, the watchdog resets the system hard-
ware after its counter reaches zero.