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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.

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