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MT8880C DTMF transceiver with  9S12C128

Question asked by Nigel Johnson on Apr 8, 2014
Latest reply on Apr 16, 2014 by Carl Barnes

I am trying to use the MT8880C DTMF transceiver in a ham radio repeater controller, using the 9S12C128 chip, and programming it with gcc.

 

I have it working fine for output setting it up by the instructions in the data sheet. As part of a POST, I send all the DTMF digits in non-burst mode OK.

 

Again, following the guide in the data sheet, when I add the code to read the data register when I get an IRQ from valid DTMF, it subsequently starts sending constant tone even though I don;t tell it to, and forever hold the IRQ line down LO.@

 

I am hoping someone has been there before and can shine some light on the problem!

 

thanks for any help,

 

Nigel ve3id

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