User`s manual

Utilities 47
5 Utilities
5.1 Watchdog Timer
This section explains the operation of the cPCI-6841’s watchdog
timer. The primary function of the watchdog timer is to monitor the
cPCI-6841 Series SBC’s operation and to reset the system if the
software fails to function as programmed. The watchdog timer can
be software controlled in the following ways:
X enabled and disabled
X reloading timeout value
Figure 5-1: cPCI-6841 Watchdog Timer Architecture
The CPCI-6841 Series custom watchdog timer circuit is imple-
mented using the Winbond W83627HF. It contains three Registers
(CRF5, CRF6 and CRF7 of logical device 8) for controlling the
watchdog timer and retrieving its status. The basic functions of the
watchdog timer are:
X Set the timeout interval of the watchdog
X Start timer count down
X Enable/disable watchdog
X Reload the timeout value to keep watchog from timing out
X Set the range of the timeout period from 1 to 255 seconds,
or 1 to 255 minutes. It is set by control register.