POSENC - Quadrature and step/direction encoder
==============================================
The POSENC block handles the Quadrature and step/direction encoding

Fields
------

.. block_fields:: modules/posenc/posenc.block.ini


Quadrature
----------

When in the quadrature mode, the module will output signals A and B in different
states as it counts up or down. When counting up B will follow A and when
counting down A will follow B. The period is the time between an edge on one
signal to the next edge of the other signal.

The input is initially set as the value of the INP line when ENABLE goes high.
The system will then count to the current value on the INP line, and when it
reaches this value the output signals will stay as they are.

The state output is '0' while ENABLE is low, '1' when the count is equal to the
signal on the INP line and '2' while it is counting towards the INP value.

.. timing_plot::
        :path: modules/posenc/posenc_documentation.timing.ini
        :section: Quadrature rising and falling

.. timing_plot::
        :path: modules/posenc/posenc_documentation.timing.ini
        :section: Longer Period Quadrature


Step/Direction
--------------

In the Step/Direction mode the A output becomes a step output. This goes high on
every period for one clock cycle and is low for the remainder of the period. The
B output becomes the direction output, it is '0' when the internal counter is
lower than the inputted target value (it is counting up), and '1' when it is
greater or equal to.

.. timing_plot::
        :path: modules/posenc/posenc_documentation.timing.ini
        :section: Step/Direction

.. timing_plot::
        :path: modules/posenc/posenc_documentation.timing.ini
        :section: Longer Period Step/Direction