ADLINK Technology cPCI-3615 Series, Руководство пользователя

Страница: 81 / 114

Utilities 67
cPCI-3615
7 Utilities
7.1 Watchdog Timer
This section describes the operation of the cPCI-3615’s watchdog
timer (WDT). The primary function of the WDT is to monitor the
cPCI-3615's operation and to reset the system if a software appli-
cation fails to function as programmed. The following WDT func-
tions may be controlled using a software application:
X enabling and disabling
X reloading timeout value
The cPCI-3615 custom WDT circuit is implemented using the
internal I/O of the ITE SuperIO IT8783 which is at 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 tim-
ing out
X Setting the range of the timeout period from 1 second or minute
to maximum 65635 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
cPCI-3615's SuperIO.
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.
For a detailed programming sample, refer to the sample code pro-
vided in the ADLINK All-In-One CD. You can find it in the following
directory:
X:\cPCI\cPCI-3615\WDT .