markfickett / rotary-dial

Arduino library to receive numbers dialed by a rotary telephone dial via pulse dialing

Rotary Dial

Arduino library to read numbers from a rotary dial (or otherwise using pulse dialing; see Wikipedia: Rotary dial).

This implementation is for the North American system, where [1, 9] pulses correspond to the numbers [1, 9], and 0 is represented by 10 pulses. This library was written for use with the dial demonstrated here and pictured above.

Connection & Circuit

On the back of the dial are two connections relevant for this implementation. One (the 'ready' switch) is normally open (NO), and is closed whenever the rotor is not at rest (specifically, as soon as the user draws back the rotor, and until it finishes returning). The other (the 'pulse' switch) is normally closed (NC), and is opened briefly for each pulse (roughly 10 - 20 Hz).

The expected circuit is:

     Rotary Dial                              Arduino
                      /---------------------- readyPin
  /- ready switch (NO) -- pull-up resistor -- VCC
 /-- pulse switch (NC) -- pull-up resistor -/
 \                    \---------------------- pulsePin
  \------------------------------------------ GND

The expected sequence is:

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

There is 15ms allowed for debounce, which is the implementation's only constraint on pulse speed.

See Also

Interrupt-based variant of reading a rotary dial.

rotary-dial's Issues

Opeartion without READY PIN

I think it's not needed to use READY PIN, this can be implemented by using PULSE PIN alone.

Start counting pulses once first pulse is received.
Stop counting pulses and output the number if there was no pulse for predefined amount of time.
There are telephone standarts which define pulse durations and delays, so this can be reliably determined without need for second helping pin.

Even the phone line itself does not use this ready pin. They only use two wires for everything (dialing, ringing and voice). So there's no reason to use 3 wires to connect the dialer to arduino...

Can you please add such mode?

Add to arduino library manager

Hello, can you please prepare your library for inclusion in arduino library manager?

1.) Move your library sources to src/ subdirectory
2.) Add library.properties file ( See this for example: https://github.com/harvie/ps2dev )
3.) Add version tag to your git according to library.properties (eg.: v0.0.1)
4.) Request listing here: https://github.com/arduino/arduino/issues