Need help with mt8870DE in myanmar

[ramza038]

I am from myanmar. I joined mt8870de with headset from my mobile. I used components value from datasheet. But it doesn't work. Plz help me.

 

[simonbramble]

Firstly, thanks for introducing yourself. I had never heard to Myanmar until now... The chip you are trying to use is a DTMF decoder:
https://www.futurlec.com/Zarlink/MT8870DE.shtml

The numbers on a telephone keypad are arranged in rows and columns. Thus button 1 is row 1, column 1. Button 6 is row 2, column 3. When you press the numbers on a typical telephone keypad, it generates 2 tones, one according to the row and one according to the column.

This chip decodes these 2 tones into 4 logic outputs, thus connecting it to your headset will not work. Your headset is expecting an analogue signal and you are giving it a digital one.

It sounds like what you are trying to do it beyond the abilities of this forum, but good luck

 

[ramza038]

I know and i used the component as in datasheet but it doesn't work.i uesed single ended cinfig. Plz help me.

 

[atferrari]

You insist in asking questions about a circuit that you only know. Would you expect an answer from that?

 

[Mikebits]

Your signal level from the headset may be incorrect. You may need to change the gain of the input stage of the decoder. See the data sheet (GS pin).

 

[gagandeep]

hi ,
i am interfacing dtmf 8870 with p89v51rd2, View attachment 63776 circuit attached
i am not getting desired led outputs by connecting nokia phone
please help
RD pin of 8051 to be connected????