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Analog Angle Article

Why I love a real reset switch–and why you should design one in (if you can)

The so-called on/off switch many of today's products is a misnomer. In many designs, it's really a “soft-switch” function that puts the unit to sleep, but doesn't actually disconnect the power supply. And even if the switch does truly turn the power off, so what? All that nonvolatile memory has locked in your set-up and preferences, and you can't clear them. So then what do you do?

This situation became painfully clear to me when my home network crashed. It's a fairly basic setup, with a DSL modem and a router; the router supports two hard-wired PCs and one, and sometimes two, wireless connections. When the system went crashed, I shut everything down, and restarted the PCs, the modem, and the router. When that didn't work, I stripped the system back to its basic configuration of the DSL modem alone and one hardwired PC, which I eventually got to work (I'll spare you the details, I am sure you have similar stories).

I thought my problems were over, as I would just have to add back the router, recable, power up, and be done. A few hours later, the router still would not work, even though I even re-loaded the router's set-up CD and followed all the fresh-start installation steps. I checked cables for proper connections and even verified each cable's integrity, since my past experience has taught me the hard way that the very process of debugging often induces new, unrelated problems, especially with cables which are repeatedly disconnected and reconnected. (Although neither the modem nor router has an on/off switch, I cut and restored their power by using a companion dc-power switchbox I built out of sheer frustration, see “Strong satisfaction from simple projects”.)

Finally, in desperation, I started going through the 150-page router reference manual which was on the CD along with the setup wizard. One small part caught my eye: it said that you could do a real reset to “factory-fresh” conditions by using a straightened paper clip to push a tiny reset button hidden inside, behind one of the many small, identical-looking vent holes in the back of the unit. I did that and was then able to re-initialize the router, configure it, and network just fine. All was well, at last.

I assume the router circuitry had somehow dropped a bit, lost its way, whatever. I'll never know since there are no available forensics or logging tools. What matters is that even re-doing the basic initialization process did not help, and powering up and down also was of no use. It took a real, switch-induced reset to restore the router to its original state. I thank the designers for putting it in, even if they hid it well!

And does your product need one? It's no admission of imperfection on your part to put one in, even if hidden. Even in the best designs, stuff happens! ♦

1 comment on “Why I love a real reset switch–and why you should design one in (if you can)

  1. MarioFred
    April 20, 2020

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