PIC16F628 phone dialer

DTMFOUT Pin,{Onms,Offms,}[Tone{,Tone...}] Produce DTMF touch Tone sequence on Pin. Pin is automatically made an output. Pin may be a constant, 0-15, or a variable that contains a number 0-15 (e.g. B0) or a pin name (e.g. PORTA.0).
Onms is the number of milliseconds to sound each tone and Offms is the number of milliseconds to pause between each tone. If they are not specified, Onms defaults to 200ms and Offms defaults to 50ms.
Tones are numbered 0-15. Tones 0-9 are the same as on a telephone keypad. Tone 10 is the * key, Tone 11 is the # key and Tones 12-15 correspond to the extended keys A-D.
DTMFOUT uses FREQOUT to generate the dual tones. FREQOUT generates tones using a form of pulse width modulation. The raw data coming out of the pin looks pretty scary. Some kind of filter is usually necessary to smooth the signal to a sine wave get rid of some of the harmonics that are generated:

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ClydeCrashKop said:

I found this today from a Gadget Freak link.
Do-it-yourself phone dialer security system calls your cell phone, office etc.
whenever a door or window is opened, or panic button is pressed. Great Home Alarm.
**broken link removed**

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Circuit Operation:

In operation, the switch closure is detected on pin 7 of the processor
which activates the reed relay and takes the line off-hook for 3 seconds
to establish the dial tone. The processor then dials the number by opening
and closing the relay a number of times for each digit. [COLOR="Red"]When dialing is
complete, the processor waits 3 seconds and then transmits a steady tone
of about 300Hz for 30 seconds through the modem transformer.[/COLOR] The call is
then terminated and the processor waits for the switch to open before resetting.

Gayan Soyza said:

Does anybody knows whats the purpose of this steady tone of 300Hz after pulse dialing?

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Pommie said:

So, the person receiving the call doesn't think it's a random call. Ideally, it would send out a recorded message but 300Hz is a lot easier to implement.

Mike.

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Gayan Soyza said:

Understood.So the person receiving the call hears that Signal 300Hz.If no signal transmitted withing the 30 second mark no any signal hears.

How stupid am I

Thanks Brother.

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blueroomelectronics said:

You could upgrade it to DTMF (touch tone) with the free demo version of PICBASIC Pro, only 40lines of code in the free version but you should be able to make a simple alarm & dialer if you're careful.
From the PICBASIC Pro manual
**broken link removed**

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