Quadrature Decoder (QuadDec)

The Quadrature Decoder (QuadDec) Component gives you the ability to count transitions on a pair of digital signals. The signals are typically provided by a speed/position feedback system mounted on a motor or trackball.

The signals, typically called A and B, are positioned 90 degrees out of phase, which results in a Gray code output. A Gray code is a sequence where only one bit changes on each count. This is essential to avoid glitches. It also allows detection of direction and relative position. A third optional signal, named Index, is used as a reference to establish an absolute position once per rotation.