On Fri, 28 Apr 2000, Dmitry Kiryashov wrote:

> You can take 12C672 and write your own one.
> That is not so hard. Also it fits 8dip.

Yeah, you tell him Dmitry. It's a piece of cake! All you got do is go to
http://www.dattalo.com/technical/theory/dtmf.html and rack your noodle for a
couple of hours and the code will drizzle right out. Once you get the decoder
working, you can goto http://www.dattalo.com/technical/software/pic/picsine.html
and figure out how to mix two sine waves for the DTMF transmitter. Trivial! I2C?
I can't give you that one since it belongs to a former employer. Shouldn't take
more than a few hours to write though. Eh?

Sarcasm aside, this is quite a bit of work. I never have heard of an IC such as
the one you wish to have. I'd suggest using an off-the-shelf DTMF decoder and a
PIC. The pic can do the I2C/SPI and the DTMF generator. The dedicated DTMF
decoder is more reliable than a plain ol' PIC.

Scott