Emergency Stop

(Summer Circuits 2010 article)

The big fear of every developer of a microcontroller or computer-driven control system is that the computer or controller could crash while it is in the middle of controlling something and that the output signal will remain on 'full throttle'. In this scenario motors could continue to spin faster and faster or a heating element could become red hot, without the system taking any corrective action. In reality, any control system needs some sort of emergency stop, which will turn everything off the moment something goes wrong.