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Quadrature Decoder (QuadDec) | Cypress Semiconductor

Quadrature Decoder (QuadDec)

Last Updated: 
Apr 20, 2016
  • Adjustable counter size: 8, 16, or 32 bits
  • Counter resolution of 1x, 2x, or 4x the frequency of the A and B inputs, for more accurate determination of position or speed
  • Optional index input to determine absolute position
  • Optional glitch filtering to reduce the impact of system-generated noise on the inputs
Symbol Diagram

General Description

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.

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