dtmf project for pic 16f84

[jkmadsci]

As a brain tease i once tried to program a pic 1684 as a standalone
dtmf decoder. I used the atod function and was able to read the signals
very clearly. The only idea that helped was to count the frequency of the wave.
This solution only decoded the 3 columns. If anyone has any ideas i would greatly appreciate the help. P.S. i fully understand the dtmf concept
, but cant seem to generate an algorithem that breaks down the wave.
Ive also tried using qbasic to reproduce the waves on the pc screen to get a glimpse at what to do, but even having all 12 patterns in front of me i cant figure it out???

 

[StupidDum]

To know knowledge, it couldnt be decoded using software on PIC.
I would suggest you to use DTMF decoder IC to simplify thing.

 

[Nigel Goodwin]

The problem is that DTMF is two unrelated frequencies at the same time, so you can't do a simple frequency count. You would probably need to use FFT (Fast Fourier Transform) to do it purely in software.

You might like to look at , which may give some ideas.