interfacing

Started by npp February 1, 2006
is there any important point to be considered while interfacing the
DTMF chip to the phone line?
i 'm currently working on a DTMF decoder proj and got stuck at the
interfacing between the telephone line and the DTMF MT8870 and the
interfacing between MT8870 and PIC18F452.
somebody pls suggest me on this. 
thanks.

npp wrote:
> is there any important point to be considered while interfacing the > DTMF chip to the phone line? > i 'm currently working on a DTMF decoder proj and got stuck at the > interfacing between the telephone line and the DTMF MT8870 and the > interfacing between MT8870 and PIC18F452. > somebody pls suggest me on this. > thanks.
My suggestion is to be more specific about where you are stuck. Cheers! --M
The most important point to consider would be that, without a line
interface circuit, the chip will likely fry.  Check out
http://assets.zarlink.com/AN/msan_108.pdf for the recommended line
interface circuit and some hints regarding the chip-to-pic interface.
Hope this helps.  BR, Dan