Problem: Powercycle microcontroller when it stops transmitting a signal (heartbeat)

Question: What device can I use to detect the signal and send an output signal? I am looking for something small as this devices function is very simplistic. (another microcontroller? timer? etc...)

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    \$\begingroup\$ What about the internal watchdog? \$\endgroup\$ – Todor Simeonov Oct 5 '17 at 16:51
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    \$\begingroup\$ Your stated problem is not a problem, but a proposed workaround. A crutch. You should understand why it is stopping the transmission in the first place. \$\endgroup\$ – Eugene Sh. Oct 5 '17 at 16:53
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    \$\begingroup\$ Are you looking for a complete power-cycle of a microcontroller and the entire surrounding circuit's low impedance voltage rail, as well, and not just a microcontroller or circuit "reset" pulse? \$\endgroup\$ – jonk Oct 5 '17 at 17:18
  • \$\begingroup\$ @EugeneSh. You are correct this is a workaround but I need to install this since some crashes occur randomly (network fail, component crash, memory fail) and I am too far away to manually reboot \$\endgroup\$ – SChand Oct 5 '17 at 17:55
  • \$\begingroup\$ @TodorSimeonov is the internal watchdog 100% reliable? I have to make sure the system I put in place will never need intervention unless a cable is cut or unit unplugged \$\endgroup\$ – SChand Oct 5 '17 at 17:56

What you are looking for is called a "watchdog circuit" or "watchdog timer". They make cheap single ICs that can do this for you. Your microcontroller may even already have one built-in!

Look here.

Here is a datasheet for a common one.

  • \$\begingroup\$ is it possible to do this watchdog reset when a script crashes? \$\endgroup\$ – SChand Oct 7 '17 at 0:11
  • \$\begingroup\$ Yes. You would have the script toggle a pin on the watchdog timer. When the script crashes the timer stops getting the input and triggers a reset. \$\endgroup\$ – evildemonic Oct 9 '17 at 14:49

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