about dtmf

hi everyone.
i m new to arduino so no much idea.can anyone help me with the arduino coding for device control using dtmf.any suggestions are heartly welcomed.

"device control using dtmf"

What is your intent? Most folks seem to want to generate dtmf (google tone library dtmf) or decode dtmf (seems to require external chip, google shows those as well).

thanks for the quick reply.
i m intending to automatic hook off telephone line after 3-4 rings n then device control using dtmf.i m using mt8870 decoder for decoding the dual tone.the problem is the said this is 4 bit decoder but use 5 pins for output.can u help plz.

http://pdf1.alldatasheet.com/datasheet-pdf/view/77085/MITEL/MT8870.html My reading of the datasheet says you get the 4 bit output Q1-4, and a 5th pin STD that goes High to tell you when Q1-4 have valid data on them.

4 bit decoder but use 5 pins for output.can u help plz.

You need a 16 pin demultiplex chip or two 74HC238 demultiplex chips like shown on the below sweet 16 dtmf decoder.

http://www.rainbowkits.com/kits/TT-16p.html

zoomkat,

The MT8870 appears to provide a hex 0 to F output, one just needs to latch that output when the STD line goes high. Seems much simpler than messing around with 16 voltages.

I'm sure it would take quite a while to get that over to India as well. maharjan, you are in India, yes? You should update your profile with location.

The MT8870 appears to provide a hex 0 to F output, one just needs to latch that output when the STD line goes high. Seems much simpler than messing around with 16 voltages.

I suppose that equates to connecting Q1-Q4 to four arduino digital inputs and using a truth table in the arduino code for those four inputs.

Or shift them in, then do a switch(dtmf){case 0:, case 1:, etc} action with them.

I suppose that equates to connecting Q1-Q4 to four arduino digital inputs and using a truth table in the arduino code for those four inputs.

Yup thats how I would do it... perhaps put it all on the same port with the latch on an interrupt...will make it easier...