It doesn't have to be instantaneous in processor time. I'm willing to go a =

few cycles. I doubt anyone would notice a few microsecond of lag time. But, =

I agree with you about using an external circuit to provide a logical =

signal. Easier to work with.
Thank you

----- Original Message -----
From: "Jan-Erik S=F6derholm" <jan-erik.soderholm@telia.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Saturday, November 11, 2006 8:15 PM
Subject: Re: [PIC] signal detection

> dax2@hotmail.com wrote :
> > I need to use a 12F675 to detect an audio signal of
> > about a volt.  Any ideas ?
> > Thank you.
>
>
> Hi.
>
> How fast do you have to "detect" and also how fast
> do you have to detect that there is *no* audio signal ?
>
> The easiest way (for the PIC) is of course to build a
> simple external circuit that gives a logical high or low
> when detecting the signal. Then you can use a simple
> digital I/O pin and get a little shorter (and faster)
> PIC code.
>
> One problem with "reading" the original audio signal,
> is that you *could* be doing the ADC-conversion right
> when the level is low enought to give a false "no-audio"
> answer. So you probably whant to have some signal
> smothing (integration) circuit anyway. This depends
> on what reaction times you expect.
> Best Regards,
> Jan-Erik.
>
>
>
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