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DTMF Tranciever MT8880

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Noman Yousaf

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Nov 19, 2003
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Lahore Pakistan
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i want to use MT8880 transiever i read the data sheet but could'nt under stand, how to use.
i can use assambly language of AT89XXXX.
if any body has used it, please tell me how to use it as encoder at least.
or any othe ic which can be used as dtmf encoder.

thanks in advance

pic mt8880

Hi Noman,
DTMF encoder is an IC which produces a combination of two frequencies depending upon the number pressed.
Just connect the IC as per the datasheet it will work.
No need to programing MT8880 it is just an encoder.

If you needto interface to microcontroller few lines
like D3,D2,D1,D0, CS etc has to be connected to microcontroller.
The interface is as simple as turn on MT8880 and write required number into
four data pins, or read from from it. Some DTMF decoders have Data valid signal as output. (Refer Holtek DTMF decoders)

MT8880 Interface to PIC is given in the link below
**broken link removed**

mt8880 circuit

this file contains a cm8870 DTMF decoder interfaced with AT89c51.
also the circuit has a ring detection function
hope that help u


mt8880 dtmf pdf

hi noman,it is exactly what sudhir.k.a told.
u just connect the sample circuit given in the data need of going for microcontroller.

mt8880 interfacing with pic

Noman I did the same thing with an 89C52.

You can refer to the pdf document as posted above.
In the software, set up 4 pins for input.
you also need another input pin for STD.

In the source code just poll STD. When it goes high, read 4 bit port for number pressed. You will probably need some debouncing code also. What I did was just wait until STD went low, then proceed to read port.

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