SOIC DTMF encoder/decoder IC needed

"Phil in Melbourne" a écrit dans le message de news:

DTMF chips are definitively obsolete, as everybody is now doing DTMF generation and detection by software. The easiest solution would be I think to use a low cost microcontroller with built-in analog resources, like the PSoC from Cypress (in particular as the PSoC Designer development tools do support DTMF generation, and as applications notes exists I think for DTMF detection...). The smallest chips will probably be enough.

Friendly, Robert Lacoste

There is no need for a dedicated DTMF chip. The DTMF encoding and decoding is perfectly done by a microcontroller.

Vladimir Vassilevsky DSP and Mixed Signal Consultant

Try Google on "CML Micro".

...and, for detection, often not as well as the dedicated ICs did. There were a lot of clever techniques used back then to avoid falsing and really dig signals out of the mud, whereas if you look at the app notes for doing it in software today, the quality tends to be all over the board. Many don't even use the old Bell Labs test tapes that were specifically designed to characterize the quality of a decoder.

Granted, with almost all phone calls going digital except for the last bit of analog between a home and a concentrator/central office, lower quality DTMF decoders aren't as much of a problem as they once might have been.

See the PDF of my patent...

at

Nothing quite beats analog for pulling signals out of the noise.

...Jim Thompson

Hope these are useful.