Post by thread:DTMF Recognition/generation with PIC only

HI! How can I recognize/generate a DTMF tone with only a pic? Thanks very much! Andrew ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: dl.http://www.juno.com/get/tagj.

Andrew, I've done something similar (but not DTMF) and have used an A/D within the PIC to capture the signal and determine it's "approximate" frequency by a math routine. This PIC is the 8-pin 12C671 (as an example). David {Original Message removed}

You can get theory on it from http://www.dattalo.com/technical/theory/dtmf.html Didn't there used to be some DTMF code there, Mr. Dattalo? -Randy Glenn spam_OUTPICxpertTakeThisOuTtechie.com - http://i.am/PICxpert Ineptitude is a sure indicator of intellect. =========== To unsubscribe, send a message containing the text "unsubscribe PICLIST" to .....LISTSERVKILLspam@spam@MITVMA.MIT.EDU {Original Message removed}

On Sat, 11 Mar 2000, Randy Glenn wrote: > You can get theory on it from > http://www.dattalo.com/technical/theory/dtmf.html > > Didn't there used to be some DTMF code there, Mr. Dattalo? No. I had written some MATLAB/Octave programs to do some of the theoretical analysis, but I never did make the code public. The PIC code I did write was for a contract and consequently can't be disclosed. Prior to the contract, I did have a version that didn't work too well. A few people saw it (and the MATLAB code), but I really don't want to release it. Since the contract I had thought of another way to implement the algorithm. Unfortunately, it takes a considerable amount of time to thoroughly test this. BTW, the algorithm - which is described on the web page, is public. It is only the code (written by me) that implements it that is not public. But, in all honesty I'd recommend getting a DTMF decoder IC. The only reason to implement this is if cost or space is a really critical issue. Scott

<snip> > But, in all honesty I'd recommend getting a DTMF decoder IC. The > only reason to implement this is if cost or space is a really critical > issue. Decoders are not available from digikey or I wouldn't be asking this question. Decoders *WERE* available but are now 'no longer carried' or 'obsolete'. Also space is a *small* issue. Thanks, Andrew > Scott ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: dl.http://www.juno.com/get/tagj.

>----- Original Message ----- >From: Andrew T Kelley <k_andrewKILLspamJUNO.COM> >To: <.....PICLISTKILLspam.....MITVMA.MIT.EDU> >Sent: Saturday, March 11, 2000 2:30 PM >Subject: DTMF Recognition/generation with PIC only > >> HI! >> How can I recognize/generate a DTMF tone with only a pic? >> >> Thanks very much! >> Andrew >> If you are really intent on doing it with a PIC, you might checkout something called "Goertzel's algorithm", but I don't know where you can get code for it. It's a real tone filtering algorithm, and not something that counts zero-crossings, etc. Requires analog A/D input. I once did some calculations and decided a PIC running at 4 Mhz could do Goertzel just fast enough to meet the DTMF minimum speed requirements - better if running 10-20 Mhz. However, then I just went ahead and used a $5 MC145436 chip anyway. [what can I say?]. BTW, I still have a few of the '436 chips left that I could part with for less than what I paid for them [did I say that?]. regards, - Dan Michaels Oricom Technologies http://www.sni.net/~oricom ==========================

<x-flowed>Scenix has a Virtual Peripheral to do this for the SX parts. http://www.scenix.com. Bill >From: Dan Michaels <EraseMEoricomspam_OUTTakeThisOuTLYNX.SNI.NET> >Reply-To: pic microcontroller discussion list <PICLISTspam_OUTMITVMA.MIT.EDU> >To: @spam@PICLISTKILLspamMITVMA.MIT.EDU >Subject: Re: DTMF Recognition/generation with PIC only >Date: Sat, 11 Mar 2000 18:52:38 -0700 > > >{Original Message removed}

Harris CD22204 DTMF Receiver, $4.00 at Gerber. Andrew T Kelley wrote: > Decoders are not available from digikey or I wouldn't be asking this > question. Decoders *WERE* available but are now 'no longer carried' or > 'obsolete'. Also space is a *small* issue.

>Harris CD22204 DTMF Receiver, $4.00 at Gerber. Andrew T Kelley wrote: > Decoders are not available from digikey or I wouldn't be asking this > question. Decoders *WERE* available but are now 'no longer carried' or > 'obsolete'. Also space is a *small* issue. Motorola MC145436P DTMF decoder (pin for pin compatible with SSI 204 chip) - $2.49 !! at JDR(http://www.jdr.com) See ARRL 1990 Handbook (p. 34-3) for a simple DTMF decoder project that works very well and has good noise immunity - MC145436P and 4514 (4 bit latch/ 4-16 decoder) are the only chips. PC boards available from FAR Circuits at http://www.cl.ais.net/farcir/ ("SIMPLE DTMF DECODER USING THE SSI202 IC WITH BCD & DECADE OUTPUT FOR LED's" and he might well have copies of the original article. I have built 2 and there are probably thousands in use by hams. Charlie WA2IPZ Burley, Idaho KILLspamcstackKILLspamsafelink.net

Hi, AFAIK the MT8870 is generally available. It does a wonder, really! Regards, Imre On Sat, 11 Mar 2000, Andrew T Kelley wrote: {Quote hidden}> <snip> > > But, in all honesty I'd recommend getting a DTMF decoder IC. The > > only reason to implement this is if cost or space is a really critical > > issue. > > Decoders are not available from digikey or I wouldn't be asking this > question. Decoders *WERE* available but are now 'no longer carried' or > 'obsolete'. Also space is a *small* issue. > > Thanks, > Andrew > > > Scott > > ________________________________________________________________ > YOU'RE PAYING TOO MUCH FOR THE INTERNET! > Juno now offers FREE Internet Access! > Try it today - there's no risk! For your FREE software, visit: > dl.http://www.juno.com/get/tagj. > >