(LOL ... Well, I was trying ...)

So do all your systems rely on a watchdog then?

Here's what I mean.

I agree that we make things as safe as possible, especially where it's free. But there is a possible downside, and people forget this:

When software is used to protect against nasty physical problems, like intermittent spikes on a pin, that protection can be switched in for the final product, but NOT during development and testing. Otherwise, the problem might get WORSE in the field, and you'll kick yourself that you didn't know about it in test.

Suppose there was a PCB routing problem - the switch line was too near to a mains signal. There are spikes on the switch pin, but small enough to be suppressed by the debounce. Nobody knows it's there.

Now, in service, on the other side of the world, the mains is noisier. Suddenly, intermittent problems that were suppressed by software in test.

And noone has yet explained to me why a switch pin on a SBC should be more likely to get noise than an edge triggered int pin - which is more sensitive and maybe more critical.

By all means, play it safe in the field ... but ... you either trust your hardware or you don't.