FeatherPhone on Adafruit Feather 32u4 FONA

Rotary phone powered by Arduino

Circuit Connection

I use a simple connection to the rotary mechinism. In my case, the pink wire on my dial is the pulse pin. When dialing a number, the pink wire is intermittently connected to the orange wire. So…

Connect Pink wire to pin 2
Connect Orange wire to ground

Hook Detection:
The phone hook is a simple switch which is normally open.

Connect one hook wire to pin3
Connect other hook wire to ground

     Rotary Dial                              Arduino
                      /---------------------- readyPin w/pulllup
  /- ready switch (NO) 
 /-- pulse switch (NC) 
 \                    \---------------------- pulsePin w/pullup
  \------------------------------------------ GND

readyPin  pulsePin  state
HIGH      n/a       default (waiting)
LOW       LOW       ready to dial / for first pulse
LOW       HIGH      pulse received (number = 1)
LOW       LOW       ready for next pulse
LOW       HIGH      pulse received (number = 2)
LOW       ...       (repeat)
HIGH      n/a       rotation complete, count recorded

Hardware

Adafruit Feather 32u4 FONA
An ‘all-in-one’ Arduino-compatible + audio/sms/data capable cellular with built in USB and battery charging. Its an Adafruit Feather 32u4 with a FONA800 module.

Rotary Telephone
I bought one from ebay. Perfect working order as they are actually designed to last FOREVER! Mine is a BT model from the 70’s. They are cheap and fun to take apart.

Building

The project is in VSCode using the PlatformIO plugin. RoataryDial is the only additional library needed.

ToDo

Implement dialing detection
Circuit to power original bell ringer