Mr RB
Well-Known Member
Hi, I noticed recently that there had been some discussion of using DTMF and people have said the specialised DTMF chips are hard to obtain etc.
I recently created a system to generate very precise dual sinewave DTMF on any PIC that has a PWM module;
**broken link removed**
https://www.romanblack.com/SG/SG_tutorial.htm#DTMF
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Also over the last couple of days I put together a new algorithm for doing DTMF decoding even on the small slow PICs (I have included a working example on a PIC12F675).
This uses a combination of some software filtering to extract reliable periods, comparing periods and analysing the period patterns generated.
I made a simple spectrum (period) analyser to decipher the DTMF data;
**broken link removed**
And a new system to very easily detect period patterns in the DTMF data;
**broken link removed**
These 2 systems are quite open ended and can be used for other frequencies too and my PIC DTMF decoder can also decode the other telephone call signals and dialtones etc.
There's lots of data on my web page incuding C source code for the PIC 12F675 DTMF decoder;
https://www.romanblack.com/DTMF/DTMF_alg.htm
Please feel free to use these systems for very cheap DTMF generation and decoding.
I recently created a system to generate very precise dual sinewave DTMF on any PIC that has a PWM module;
**broken link removed**
https://www.romanblack.com/SG/SG_tutorial.htm#DTMF
---------------------------------------------------------
Also over the last couple of days I put together a new algorithm for doing DTMF decoding even on the small slow PICs (I have included a working example on a PIC12F675).
This uses a combination of some software filtering to extract reliable periods, comparing periods and analysing the period patterns generated.
I made a simple spectrum (period) analyser to decipher the DTMF data;
**broken link removed**
And a new system to very easily detect period patterns in the DTMF data;
**broken link removed**
These 2 systems are quite open ended and can be used for other frequencies too and my PIC DTMF decoder can also decode the other telephone call signals and dialtones etc.
There's lots of data on my web page incuding C source code for the PIC 12F675 DTMF decoder;
https://www.romanblack.com/DTMF/DTMF_alg.htm
Please feel free to use these systems for very cheap DTMF generation and decoding.
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