This project is based in my father's project "DTMF remote control with PIC". http://www.atva.com.ar/dtmf_3dj/dtmf_3dj.htm (spanish)
Since I haven't time to work with PICs, I ported the project to AVR using an Atmega328p with Arduino bootloader.
This project is very similar to my father's one, because the working method is the same. We use a DTMF decoder like MT8870 or HT9170 (compatible pin to pin) to decode the analog audio signal and 'extract' the dtmf codes and convert it to a digital binary signal.
That binary signal is easily interpreted by an Arduino, after that I parse it storing the received signals into an array to command some outputs.
For the moment no. There isn't a security implementation because where i go to put this i don't need any secured system, but is very easy to develop a function to protect the controller (with a hexa password I think)
Ok thanks . I need a system that can take trigger from one Smoke sensor , one Temperature sensor and one PIR sensor and make a phone call to
some specific defined phone numbers and play the recorded voice and stop. I have temperature sensor lm35 , Analogue PIR Sensor , Arduino uno ,
a telephone instrument , SD Card , and Two relay isolated module etc. i have already checked playing a wav file from sd card , DTMF tone playing , my plan is to play a dtmf tone with arduino and give its output to telephone receiver mic and all this need to work auto, I need the sequential flow of
this project pls help as i need this in my server room for security purpose. thanks for help.