Harry Febianto wrote:
>
> Hi,
>
> I have a final project for my college. I plan to detect dtmf signal from
>
> telephone to be decoded. I use PIC 16F84. And I have some
> possibilities/theorys. Using interrupt and counter together or counter
> only
> or ADC 1bit (or 8 bit ADC).
>
> I think I need some literatures, and many thanks if you can give me some
>
> references that I can download. Which one is better for above theorys ?
> Or
> do you have any advise or some example program ?
>
> Thank you very much for your help.
>
> Best Regards,
>
> Harry Febianto

As others have already said, using a dedicated DTMF decoder IC is the
preferred way to decode DTMF. But..., if you're somewhat demented like
myself then take a look at:


http://www.interstice.com/~sdattalo/technical/theory/dtmf.html

As I've said in previous posts on this subject: this algorithm works
well, but additional analog signal processing is required to make it
robust.

Scott