DTMF Shield Aimed At Ham Controlled Arduino

[Colin] wanted a way to reliably control an Arduino via ham radio. One of the easiest methods of automated radio control makes use of Dual-Tone Multi-Frequency signalling. To those who aren’t into amatuer radio you probably recognized DTMF as the touch-tone system for telephone communications. [Colin] built a shield that has an audio input and can decode DTMF signals.

The hardware is based around an MT8870 DTMF decoder chip. This is a popular choice for DTMF hardware because it does all of the decoding work for you. Whenever a valid tone is detected it outputs the associated value in binary on four output pins. There is a fifth pin that strobes after each new tone. [Colin’s] design offers a lot of feedback for what’s going on with the input signal. The DTMF value is displayed on a 7-segment display (controlled completely in hardware), the value is output on for Binary Coded Decimal pins, and mapped to a set of ten pins which pull to ground to match the digit received.

8 thoughts on “DTMF Shield Aimed At Ham Controlled Arduino

  1. A couple years ago I wrote a software only DTFM decoding on a ‘168 chip. It used about 15% CPU while running at 11.0592 MHz (it was a 3 volt system). The goetzel algorithm was coded in assembly with lots of aggressive optimizations (a test version in C could barely implement 1 of the 7 filters at nearly 100% CPU).

    Maybe I ought to dig that code up and turn it into a nice Arduino library?

Leave a Reply to Vince086 Cancel reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.