Lanner LEC-7220 - Manual (Page 19)

19
Programming Watchdog Timer
Embedded and Industrial Computing
Appendix A
Appendix A:
Programming System
Watchdog Timer of the
LEC-7220
A watchdog timer is a piece of hardware that can be
used to automatically detect system anomalies and reset
the processor in case there are any problems. Generally
speaking, a watchdog timer is based on a counter that
counts down from an initial value to zero. The software
selects the counter’s initial value and periodically restarts
it. Should the counter reach zero before the software
restarts it, the software is presumed to be malfunctioning
and the processor’s reset signal is asserted. Thus, the
processor will be restarted as if a human operator had
cycled the power.
For sample watchdog code, see watchdog folder under
LEC-7220 Utility on the Driver and Manual CD
Executing through the Command Line:
Execute the WD.EXE file under DOS (WD.EXE and CWSDPMI.
EXE should be placed on same directory), then enter the
values from 0~255. The system will reboot automatically
according to the time-out you set.