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A software based DTMF Remote control

The intent of this project was to build a software DTMF decoder which is run on PIC microcontroller. No any external decoder IC is needed only few external components. DTMF control is convenient where phone line is present, as device can share it with other phone devices.


In this particular project remote receiver can control 4 outputs that can drive up to 10Amps at 12VAC. Device accept three commands: SET, RESET and Check output status. Controller is password protected. All values including password are stored in EEPROM memory. Probably most interesting part in this project is software DTMF decoding as this task is usually done by DSP or specialized chips. Decoding is based on Goertzel algorithm. So here is some challenging ASM coding done, but results are positive. Check out the ASM source.

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  2. Here is a pure software based DTMF decoder:


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