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Hi I'm trying to interface this transceiver chip with my avr. I understand the databits should be connected to my avr. However am unsure of what to do with the rest of the pins. Also how would you get the chip to dial a number.

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3 Answers

up vote 3 down vote

The datasheet doesn't give a timing diagram for writing to the MT8889, but it contains a number of connection diagrams for different processors, like this one:

enter image description here

I would consult write timing diagram in the microprocessor's datasheet to see how the different signals relate.

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He's using an AVR so he only needs a single output to drive the CS pin. – Leon Heller Apr 16 '11 at 10:35
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I'd forget about that chip and implement DTMF transmission in software. Here is an Atmel app. note describing DTMF generation. It's cheaper than using an external chip, and the frequencies may be fine-tuned if necessary. Given the complexity of the MT8889CE interface, using the Atmel software will save a lot of time.

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you don't explain why the software solution would be better. Also, the Atmel appnote only describes a generator, while the MT8889 is a generator/decoder. – stevenvh Apr 16 '11 at 9:34
He only wants a dialler! – Leon Heller Apr 16 '11 at 9:41
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Okay, but why is the software solution better? – stevenvh Apr 16 '11 at 10:07
I added it to my answer, although it's quite obvious! – Leon Heller Apr 16 '11 at 10:26
up vote 0 down vote

Please see the circuit below. I have this IC connected to ATMega162.

enter image description here

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