interfacing dtmf with atmega644p

how do i interface a dtmf decoder with an atmega644p...???wat does the PIND command do???

Also i need to use the dtmf signal as interrupt..can it be done???

Which DTMF decoder chip are you using???

Usually they present 4 bits of data and a "Data Valid" bit...

ht9170b

OK, use the application Circuit on Page 11. HT9170B Datasheet

D0..D3 are 4 pins to digital inputs.

DV (Data Valid) can be polled or you could use it as an interrupt...

The table of 4-bit values and DTMF codes are on page 10..

I have code for DTMF receive (with interrupt) and transmit on my blog . . .

Someone here:

with a similar problem.

w(h)at does the PIND command do???

PIND is the microprocessor register that is used to read the data that some external device (your DTMF decoder) has put on the microcessor pins corresponding to Port D.

PIND must therefore be an Arduino command to read that information and one would expect to find an explanation/example in the 'Port Manipulation' information at Arduino Reference - Arduino Reference. I couldn't find either one.

Using the 'Data Valid' signal to trigger an interrupt and using Port Manipulation to read the DTMF information is about as straightforward as you can get when it comes to your interfacing project.

Don