cellphone operated land rover connection to mobile phone problematic

Posted on Feb 6, 2014

Using Nokia 2300 for my project and the original earphones that came with it. They work properly when listening to radio, or talking to someone over the phone. However, the MT8870 IC does not give output when I connect it to my AT89S52 microcontroller. I have written a simple program to transfer everything from port 0 to port 1 (in which an LED board is connected) - so that the corresponding

cellphone operated land rover connection to mobile phone problematic
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output of the MT8870 (binary) will be shown on the LED board. But it continuously shows 0000, even on pressing keys. I would be better if you check just the MT8870 receiver part first, remove your microcontroller and see the output of DTMF decoder using multimeter. this will ensure that a part of your circuit is working fine. then you can check controller side if things are going wrong. Thank you everyone for your efforts! I went to my instructor and he suggested a few resistors and capacitor changes, am going to try that and hope it will work!

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