A neat enough article, but surprised it didn't talk about an electronic watchdog: basically pulsing a gpio pin to trigger a recharge of a cap which holds a tran

A neat enough article, but surprised it didn't talk about an electronic watchdog: basically pulsing a gpio pin to trigger a recharge of a cap which holds a transistor active for a second or so, and that transistor drives eg a relay. An alternate method uses a gpio to reset a 555 timer. This will allow machinery to cut off when the embedded circuit stops looping. That is, any attached machinery would have a guaranteed NO (normally open) circuit and can only be engaged when all the watchdogs are working properly. Some mcu pins also go into an unknown state (neither guaranteed high nor low), so resetting a cpu can have bad consequences if it's driving big machinery, if not designed correctly. One project I had a pc sending software watchdog pings to several independent devices and each of those had an actual hardware watchdog (as opposed to the cpu resetting one in the article). I used the watchdog to physically control the power to contactors: no watchdog = no power = nothing activates. The system controlled firing of gas burners and fans etc, but the design was very safe, heaps of redundancy and was guaranteed to fail into a safe mode at any instant.