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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.
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