This is the working prototype. The eagle files have some minor changes made to it. Fixed some mistakes and re-positioned a few parts.
This one is for the phreakers of the past.
A simple Arduino shield to decode DTMF tones using an audio input.
It can easily be hooked up to a cell phone or radio.
The shield uses an MT8870 to decode the audio and outputs BCD to
a 74LS145 BCD to Decimal chip. It also uses a CD4543 BCD to 7 segment
to display the number. The 74LS145 gives a logic low on one of
the ten output pins depending on what number is decoded.
The board also gives output pins for BCD that can be wired direct to the arduino
for more options. The idea came from the desire to use a ham radio to control an
arduino. Some searching led me to razorconcepts.net and my discovery of the MT8870.
I built the first version of the board and had to fix some mistakes I made.
It works great. Now I gotta get a video of it.
You can download the Eagle Files and data sheets