Arduino Foxhunt Controller for Baofeng: Adding DTMF Control

I came across a series of Youtube videos which referred me to a now defunct website where someone had posted Arduino codes for a couple of foxhunt controllers– one of which used DTMF codes to activate/deactivate or play special tone sequences. I thought that sounded nifty to potentially add to my controller, so I eventually was able to locate a copy of the Arduino code for the DTMF decoding.

Essentially, they sample one of the analog ports looking for a tone match for various DMTF codes and can trigger different responses depending on what’s decoded. Since it’s largely a software change, I was able to implement a quick add of just one additional wire — which comes from one of the mic inputs (shared with the speaker out apparently). I just added a wire over to the A0 on the Arduino and loaded up some new code to main loop to continuously check for the ‘1’ key during the wait time to turn on transmit or any other key to turn off.

This did change how I must handle delay since it is now active time. Currently, I’ve borrowed from the source code to just keep a FOR loop for an approximate time duration while checking A0 for a key, then at the end of that loop go into transmit, or return to the loop again. I’ll have to think if there’s a better way to implement this which keeps better time for the delay. It would also be nice to have a set length of time before automatically stopping transmit — say transmit for only 30 min after activation — to save transmit power on a weekend hunt where hunters will only be looking for short periods of time on their own schedule.

One other note is that since we are now using the speaker out from the Baofeng, we must make sure the volume knob is up loud enough for Arduino to read it!