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I noticed that many Smart Home projects based on DTMF communication between telephone and microcontroller. So I tried to do some experiment about DTMF. I use ATmega48 to generate DTMF signal then decode it with LC7385 decoder, because:
  1. ATmega48's 8-bit PWM output is suitable to generate DTMF tones.
  2. It has sufficient GPIO to read a 4x4 keypad and drive a LCD.
  3. ATMEL provide a application note AVR314: DTMF Generator  and example code DTMF.C.
  4. LC7385 can testify the DTMF tone which ATmega48 generated whether available or not.

sun ge 2007-10-24