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Connecting PIC to a Phone line

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lee_man_tbu

New Member
Hey everyone

I was wondering if anyone has connected a PIC too a phone line and would have any schematics for the electronics involved in doing so. I know i have too protect the PIC from the High line voltages and such.
In my application, i need the PIC too dial a phone number, the people at the other end of the phone number answer and then the PIC too receive one DTMF singal and preform an opeation on that one signal. I will probably use the PWM built in the PIC for the DTMF codes and an MT8880 IC for decoding the DTMF signals, i just do not quite understand on how too connect the circuit together.
Also, i want too have a 2 way speaker connecting too the PIC side of this application so audio communications can occur.

Any help on this would be great

Thanks
 

monkeyxp

New Member
Tele-remote control...

hope this link would help u more....
**broken link removed**

:eek:
It shows you how to interface your system to telephone line such as protection of your PIC when connecting to the phone line, ring detector, etc.

Take care of the Impedence Matching, this may be would be your nightmare.

I dont know how to use PWM to generate DTMF instead i use DTMF generator. If can, share my some resource... 8)
 

Electric Rain

New Member
Something you should know if you're working with interfacing stuff to phone lines... I've heard that your phone company could do a couple things if you do something you shouldn't. One, they could shut off your phone automatically if you try to draw any current or anything like that from the phone line. This is because they assume that something's wrong like you shorted it out somehow so they automatically shut it off to prevent electrocution. (That's just something I heard...) And two, they might charge you a fee for troubling them with trying to find out what's messing up. (Also… just something I heard.) Just trying to help. See you. :wink:

Rain
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Electric Rain said:
Something you should know if you're working with interfacing stuff to phone lines... I've heard that your phone company could do a couple things if you do something you shouldn't. One, they could shut off your phone automatically if you try to draw any current or anything like that from the phone line. This is because they assume that something's wrong like you shorted it out somehow so they automatically shut it off to prevent electrocution. (That's just something I heard...) And two, they might charge you a fee for troubling them with trying to find out what's messing up. (Also… just something I heard.) Just trying to help. See you. :wink:

Rain

In the UK it's far more serious than that, all items connected to a phone line have to be tested and approved (a process which costs many thousands of pounds). By connecting unapproved items you are liable to serious penalties, including unlimited fines!, and jail time!.
 

TheAnimus

New Member
If your in a country like the UK where they have stringent testing policies for phone devices, then try picking up an old analouge PABX, you should be able to get a 2nd hand one, that has about 6 extensions for only a few quid. As everyone wants DECT or digital ones.
 

Anu

New Member
Help

I am doing a project invloving remote monitoring of a patient using DTMF transciver MT8880 and the PIC microcontroller....I need help regarding how to interface the computer with the PIC and the PIC with the MT8880.I would also like suggestions on choosing the PIC...
i found that the link given above is invalid:
**broken link removed**
Please help.
 
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