DTMF decoder using microcontrollers?!

[sayfollah]

dtmf decoder +op amp

does anybody have an idea how to make a microcontroller (pic, atmel..) decode DTMF signals without the use of an external decoding chip?

can u help?

 

[shafee001]

dtmf decoder

you couldnot, you need filters to decode DTMF tones, which is too difficult to be built using MC assemply, it's better to use 8870 DTMF decoder

 

[Weis Guy]

microcontroller with dtmf decoder

i've done creating DTMF GENERATOR using PIC and MATRIX keypad. I've used PROTON+ PICBASIC COMPILER.maybe there's a way in decoding the output of the DTMF!ü

 

[artem]

notes on mt8870

Why you are not searching the web ? ))
**broken link removed**

 

[sayfollah]

mt8880 application

thx artem, that helped me much..

by the way, you see iam new here, how can i tell that you helped me?

 

[artem]

pic18 dtmf decoder

It does not matter to me. ) Just help others.

And of course, micrchip has very good Application notes and may be this one concerns subject as well :
DTMF Detection Using PIC18 Microcontrollers
**broken link removed**

 

[phucdull]

mt88xx and pic

Use MT8870 is the best. Why do you want to make it so hard?.

 

[Davood Amerion]

dtmf decoder in microcontroller

Hi;
you also can search the web for Goertzel algorithm.

Regards,
Davood Amerion

 

[bobcat1]

dtmf detection using microcontroller

Hi

SI-LABS have an app not for the 8051Fxxx for decoding DTMF signal all written in C language

www.silabs.com

All the best

Bobi

 

[Make_Pic]

microcontroller dtmf

Hi

SI-LABS have an app not for the 8051Fxxx for decoding DTMF signal all written in C language

www.silabs.com

All the best

Bobi

About what application you talk? AN122 - here there is only outputs DTMF tones!

Added after 20 minutes:

Hi;
you also can search the web for Goertzel algorithm.

Regards,
Davood Amerion

here there are good description of decoding DTMF tones:

**broken link removed**

 

[phucdull]

dtmf decoder+microcontroler

Suppose that a telephone (A) calls another (B). So how to know when the B picks the handset up?.
I am using MT8870 to decode numbers pressed by user. How to know when thi B picks handset up by using a MCU such as ATMEGA8515L

//Sorry for my terrible English!

 

[shmily]

dtmf decoder microcontroller c

use MT8880

 

[phucdull]

daa mt8880

use MT8880

My dear, I have just skimed the Datasheet of MT8880 as well as MT8870. But it has no pin that says when the telephone B pick the handset up. If you could do this with MT8870 or MT8880, pls show me in detail.
Thank in Advance

//Sorry for my terrible English!

 

[UroBoros]

dtmf decoder using pic microcontroller

Suppose that a telephone (A) calls another (B). So how to know when the B picks the handset up?.
I am using MT8870 to decode numbers pressed by user. How to know when thi B picks handset up by using a MCU such as ATMEGA8515L

My information in this case...

That fesility is provided by the telephone company(Exchange)

For public call office lines they are providing this feature and based on this signal the call metering system starts reading when the other party picks up.

It is done by the polarity reversal of lines I think..

I have no much idea.

but is this a clue?

please post if you find a way without the help of telephone company.

Thanks
picstudent

 

[phucdull]

decoder dtmf radio control

Ok, contineu our story. Someone have told me that when the telephone B pick handset up, the Voltage being on Telephoneline wil drop dramatically from 40V to a lower level of electric potential. Isn't it?. If so, how to recognize this by microcontroller?

 

[UroBoros]

dtmf decoder picbasic

Hai

This you are talking about the case of our first telephone (which you used to call telephone b.)

When your phone is in Hook the DC voltage will be around 48volts(+-)
When you pick up your phone the DC voltage present in the line suddenly drops to 12v or 15v range.(Varies from company to campany slightly)

The company provides a high impedence line and when telephone circutary loads that circuit it drops to 12 volts and you get dial from exchange.

If this is your situation you can detect it by a simple op amp comparator.

but my problem is how to detect weather the otherside picked or not.


with regards
picstudent

 

[phucdull]

If this is your situation you can detect it by a simple op amp comparator. But my problem is how to detect weather the otherside picked or not.


with regards
picstudent

Ok, my problem is like to you, weather the otherside picked or not.
It seems to be harder when you call a Mobilefone instead of a home phone.

//Sorry for my terrible English

 

[UroBoros]

Hai

I dont think it makes any diference weather we called Mobile or landline.

After we dial a number I think rest is controlled only by Exchange.

So that system have to pass us some information.

Let us wait for other Guys responses.

picstudent

 

[nvd]

Why not listen to ring signal heard through the speaker?

 

[UroBoros]

How?

Can you elaborate little more?

picstudent