DTMF

[riya]

Hello every one,

I want to move my robot by interfacing a mobile through a DTMF decoder. I know the h-bridge arrangement for driving the motors. I have a 9170b decoder. After establishing the call, if I press 1 the motor is on, for 2 it should be off. My doubt is how can I make to know the decoder, is there any code for DTMF decoding? My controller is pic 16f877a.

I hope you understand my problem. Please let me know about DTMF syntaxes.

Thank you.

[temtronic]

That's a Holtek chip and very easy to use,though there isn't a 'driver' here that I'm aware of.

You could tie the DataValid pin to the ExtInt pin of the PIC,and the 4 datapins to say the low nibble of PortB.
When the DTMF rcvr gets a valid tone pair, it pulses DV high,so in your ExtISR you just need to read PortB, mask off the high nibble and save the lower four bits in a variable(maybe call it new_DTMF_code ?), also set a 'flag' variable' to tell 'main' ,new data/command has arrived.then exit the ISR.

Within your 'MAIN' program, you'll need to setup a table that corresponds to the DTMF tonepairs/keypresses, similar to the 'keypad' example that CCS supplies.

Operation is simple..everytime a DTMF 'command' arrives, the ISR is entered, the datapair is stored,the 'new data flag is set' and then in 'MAIN', you decide what action is to happen(go left, forward, stop,etc) as well as clearing the new data flag.

[riya]

thank u so much sir for your response i'll ...try the code and post here.