Specifications

8.4 Watchdog Timer
The VP 110/01x board includes a hardware Watchdog timer which can be used by the operating
software to monitor the normal operation of the system. The timer is enabled by a board switch
(see Figure 8-1) and controlled by software. Once enabled it must be restarted at regular
intervals. If it is not restarted for a period of approximately 1 second, the timer will expire and
cause a Non-Maskable Interrupt or reset to the local processor. See Section 8.4.3 for further
details of watchdog timer operation.
The watchdog timer facility is provided by a Maxim MAX705 power-on reset supervisor chip and
additional hardware.
8-6 VP 110/01x
Additional Local I/O Functions
Switch4-Watchdog Timer
OFF - Enabled
ON - Disabled
ON
OFF
1
2
3
4
Figure 8-1 Watchdog Timer Switch