IEI Integration uIBX-200-VX800 v2.00 User Manual
Page 112
uIBX-200-R20/VX800 Embedded System
Page 102
NOTE:
The following discussion applies to DOS. Contact IEI support or visit the IEI
website for drivers for other operating systems.
The Watchdog Timer is a hardware-based timer that attempts to restart the system when it
stops working. The system may stop working because of external EMI or software bugs.
The Watchdog Timer ensures that standalone systems like ATMs will automatically
attempt to restart in the case of system problems.
I/O
address A61h
start counter
output A61h twice
stop counter
output A61h = 0
A tolerance of at least 10% must be maintained to avoid unknown routines within the
operating system (DOS), such as disk I/O that can be very time-consuming.
NOTE:
The Watchdog Timer is activated through software. The software
application that activates the Watchdog Timer must also deactivate it
when closed. If the Watchdog Timer is not deactivated, the system will
automatically restart after the Timer has finished its countdown.
EXAMPLE PROGRAM:
mov dx, 0A61h
mov al 03h
out dx, al
out dx, al