[sdiy] Clock signal detector

[Scott Gravenhorst]

Martin Naef <mnaef at navisto.ch> wrote:
>Is there any particular reason not to use a microcontroller for this? 
>It's an absolutely trivial single chip solution I'd personally do with 
>an AVR ATtiny25 (DIP8) and its internal counter module:
>
>- Reset counter on positive edge on pin (interrupt), set clock detect 
>output high
>- On counter overflow (or compare match), set clock detect output low.
>
>Clocking (internal) and compare value of the counter can be set freely 
>to tweak the timeout value. Power consumption will be minimal as the 
>controller will spend most of its time in sleep mode and can be clocked 
>low. It's maybe 20 lines of C code...
>

While it _could_ do the job, it's a bit of overkill.  Might be better to save a
microcontroller for something more complex and use a 555 timer in a one-shot
configuration for this.  It's one of the things the 555 was designed for.



-- ScottG
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