0.000011574Hz: The ATtiny85 super-slow-clock Saturday detector

Posted on Tuesday, March 13th, 2018 in AVR by DP


Igendel writes, “What is the lowest possible clock frequency at which a microcontroller can still do useful work? Here’s a little project that attempts to explore this weird question.”

See the full post on his blog here, It’s Every Bit For Itself.

Check out the video after the break.

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3 Responses to “0.000011574Hz: The ATtiny85 super-slow-clock Saturday detector”

  1. KH says:

    So he doesn’t really know what he’s doing. Yawn.

    It’s sensor-controlled. It’s not an oscillator. A leaf covers the window, you’re toast.

    TLV3702? Overkill. The resistors’ current is probably much more than the comparators’ current, if he followed the app note. He’s constrained by the LDR resistance range too. And the 3.3V regulator. 70uA is supposed to impress us? 70uA is really, really terrible, has he read MCU datasheets before? Another fella who thinks he’s smarter than the rest of us. Just use the RC oscillator dude.

  2. KH says:

    In the old days, these things remained on paper forever as whimsical scrawls. Today, they are brandished about on blogs for the entire world to see. Remember folks, not everything you read on blogs is of high quality.

    In short, this ‘project’ is most useful as an overhyped blog post of a useless concept. It will never be practical because it is too fragile to ever work properly for long at its purported objective. No one with more than two brain cells will ever design this thing into something that will actually be used. Please God, don’t let this person design a nuclear plant.

    This is akin to high-concept art. Like gold foil in haute cuisine.

  3. Max says:

    An actual Saturday “detector” built with the same hardware would use the precisely timed slightly varying length of the day (and some built-in astronomy data) to lock into which day out of each seven it needs to light the LED, as opposed to this implementation which relies on you to power it up on the exactly right day (fourty or so days “in advance”, no less – yay Arduino / C!). Granted, that might require access to a somewhat faster clock to do some number crunching occasionally before going back to sleep, which illustrates rather nicely the sole point of doing something like this with an MCU instead of, say, a humble three-bit counter. Other than that – unless I have some good reason to doubt a datasheet, I tend to just believe it when it says “MCU clock: from DC to x MHz”…

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