Quadrature Rotary Encoder

A Rotary encoder is a device that detects angular position. One use of this is similar to a volume control on an FM radio where the user turns a shaft and the loudness of the broadcast is changed. Incremental rotary encoders do not provide information on their exact position but supply information about how much they have moved and in which direction.

Board

Typically a quadrature rotary encoder will have two outputs A and B, perhaps called clock and data. For each part of a rotation then the A pin will provide a clock signal and the B pin will provide a data signal that is out of phase with the clock. The sign of the phase difference between the pins indicates the direction of rotation.

From above if we look at Pin B (data) at the time of a falling edge on Pin A (clk) then the if the value of pin P is 1 then the direction is clockwise and if it is 0 then the rotation is counter clockwise.

Usage

This sample shows how to implement an FM radio tuner control using the ScaledQuadradureEncoder binding. It simply prints the tuner value to the console as the knob is turned.

This binding implements scaled quadrature rotary encoder as ScaledQuadratureEncoder. The value is a double. You can for example set it up as a tuning dial for an FM radio with a range of 88.0 to 108.0 with a step of 0.1.

The code below shows an example of using the encoder as an FM tuner control.

// create a RotaryEncoder that represents an FM Radio tuning dial with a range of 88 -> 108 MHz ScaledQuadratureEncoder encoder = new ScaledQuadratureEncoder(pinA: 5, pinB: 6, PinEventTypes.Falling, pulsesPerRotation: 20, pulseIncrement: 0.1, rangeMin: 88.0, rangeMax: 108.0) { Value = 88 }; // 2 milliseconds debonce time encoder.Debounce = TimeSpan.FromMilliseconds(2); // Register to Value change events encoder.ValueChanged += (o, e) => { Debug.WriteLine($"Tuned to {e.Value}MHz"); };