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+.. currentmodule:: machine
+.. _machine.Encoder:
+
+class Encoder -- quadrature decoding
+====================================
+
+Encoder implements decoding of quadrature signals as commonly output from
+rotary encoders, by counting either up or down depending on the order of two
+input pulses.
+
+Minimal example usage::
+
+    from machine import Pin, Encoder
+
+    counter = Counter(0, Pin(0, Pin.IN), Pin(1, Pin.IN))   # create Encoder for pins 0, 1 and begin counting
+    value = counter.value()                                # retrieve current count
+
+Availability: **ESP32**
+
+Constructors
+------------
+
+.. class:: Encoder(id, ...)
+
+   Returns the singleton Encoder object for the the given *id*. Values of *id*
+   depend on a particular port and its hardware. Values 0, 1, etc. are commonly
+   used to select hardware block #0, #1, etc.
+
+   Additional arguments are passed to the :meth:`init` method described below,
+   and will cause the Encoder instance to be re-initialised and reset.
+
+   On ESP32, the *id* corresponds to a :ref:`PCNT unit <esp32.PCNT>`.
+
+Methods
+-------
+
+.. method:: Encoder.init(phase_a, phase_b, *, ...)
+
+   Initialise and reset the Encoder with the given parameters:
+
+   - *phase_a* specifies the first input pin as a
+     :ref:`machine.Pin <machine.Pin>` object.
+
+   - *phase_b* specifies the second input pin as a
+     :ref:`machine.Pin <machine.Pin>` object.
+
+   These pins may be omitted on ports that have predefined pins for a given
+   hardware block.
+
+   Additional keyword-only parameters that may be supported by a port are:
+
+   - *filter_ns* specifies a minimum period of time in nanoseconds that the
+     source signal needs to be stable for a pulse to be counted. Implementations
+     should use the longest filter supported by the hardware that is less than
+     or equal to this value. The default is 0 (no filter). *(Supported on ESP32)*
+
+   - *phases* specifies the number of signal edges to count and thus the
+     granularity of the decoding. e.g. 4 phases corresponds to "4x quadrature
+     decoding", and will result in four counts per pulse. Ports may support
+     either 1, 2, or 4 phases and the default is 1 phase. *(Supported on ESP32)*
+
+.. method:: Encoder.deinit()
+
+   Stops the Encoder, disabling any interrupts and releasing hardware resources.
+   A Soft Reset should deinitialize all Encoder objects.
+
+.. method:: Encoder.value([value])
+
+   Get, and optionally set, the encoder value as a signed integer.
+   Implementations should aim to do the get and set atomically.
+
+   See :meth:`machine.Counter.value` for details about overflow of this value.