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Keep-Alive circuit — Parallax Forums

Keep-Alive circuit

mojorizingmojorizing Posts: 249
edited 2006-05-09 13:36 in General Discussion
Is there such a standalone chip that periodically sends a serial request to a microprocessor, and if it doesn't receive a reply in a certain amount of time, it resets the microprocessor? I could use another microprocessor but I was wondering if there is a 4 pin "supervisory" chip out on the market that has this functionality.

Thanks, Kevin

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Comments

  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-05-08 22:31
    Kevin,

    most microcontrollers, like the SXes have a built-in watchdog timer. When it is activated, the software must periodically reset this timer. If it does not, the watchdog will reset the controller. IOW, if the program is going "nuts", i.e. if it does not periodically loop across the "reset watchdog" instruction, the controller will restart.

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    Greetings from Germany,

    G
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2006-05-09 13:36
    There is this little TO-92 device (TC32M)
    http://ww1.microchip.com/downloads/en/DeviceDoc/21402C.pdf
    However, it works just opposite: the mcu must toggle a pin
    on the TC32M or else the TC32M will reset the mcu.

    regards peter
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