SPIRO THE TECH GURU

Back

explained view of Watchdog Timer

By Admin on

                     A timing device such that it is set for apreset time interval and an event must occurduring that interval else the device willgenerate the timeout signal on failure to getthat event in the watched time interval. On that event, the watchdog timer isdisabled to disable generation of timeout orreset Timeout may result in processor start aservice routine or start from beginning

Example:

                    Assume that we anticipate that a set of tasksmust finish in 100 ms interval.• The watchdog timer is disabled and stoppedby the program instruction in case the tasksfinish within 100 ms interval.• In case task does not finish (not disabled bythe program instruction), watchdog timergenerates interrupts after 100 ms andexecutes a routine, which is programmed torun because there is failure of finishing thetask in anticipated interval.

Watchdog timer application:

                   An application in mobile phone is thatdisplay is off in case no GUIinteraction takes place within awatched time interval.• The interval is usually set at 15 s, 20 s,25 s, 30 s in mobile phone.• This saves power.

                   An application in temperaturecontroller is that if controller takes noaction to switch off the current withinpreset watched time interval, thecurrent is switched off and warningsignal is raised as indication ofcontroller failure. Failure to switch offcurrent may burst a boiler in whichwater is heated.


  1. A software task can also beprogrammed as a watchdog timer 
  2. Microcontroller may also provide for awatchdog timer.
SPIRO Google Plus