.. _quadrature_decode:

Quadrature Decode
-----------------

The Quadrature Decode uses two eTPU pins to decode a signal from an `incremental rotary encoder <https://en.wikipedia.org/wiki/Rotary_encoder#Incremental_rotary_encoder>`_.

.. image:: pdx_quadraturedecode_diagram1.jpg
   :width: 500
   :alt: Quadrature encoder and generated signals

How does quadrature decode work?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The OpenECU platform provides two blocks:

- **pdx_QuadratureDecode**
- **pdx_QuadratureDecodeAndFrequencyInput**

These blocks will automatically decode the input and report the number of
edges sensed. A positive number indicates forward rotation and a negative
number indicates reverse rotation. The latter block also senses the frequency
of the input waveform.