mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-12-08 20:39:01 +00:00
Fix #459 - properly support remote SPI with pigpio
Sorry! Dave's messing around with the pin implementations again. Hopefully the last time. The pin_factory is now really a factory object which can be asked to produce individual pins or pin-based interfaces like SPI (which can be supported properly via pigpio).
This commit is contained in:
Dave Jones
@@ -1,3 +1,5 @@
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# vim: set fileencoding=utf-8:
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from __future__ import (
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unicode_literals,
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absolute_import,
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@@ -6,32 +8,124 @@ from __future__ import (
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)
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str = type('')
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import io
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from .data import pi_info
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from ..exc import (
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PinInvalidFunction,
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PinSetInput,
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PinFixedPull,
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PinSPIUnsupported,
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PinPWMUnsupported,
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PinEdgeDetectUnsupported,
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SPIFixedClockMode,
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SPIFixedBitOrder,
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SPIFixedSelect,
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SPIFixedWordSize,
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)
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PINS_CLEANUP = []
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def _pins_shutdown():
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for routine in PINS_CLEANUP:
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routine()
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class Factory(object):
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"""
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Generates pins, SPI, and I2C interfaces for devices. This is an abstract
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base class for pin factories. Descendents must override:
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* :meth:`_get_address`
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* :meth:`pin_address`
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Descendents may override:
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* :meth:`close`
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* :meth:`pin`
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* :meth:`spi`
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* :meth:`_get_pi_info`
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"""
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def close(self):
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"""
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Closes the pin factory. This is expected to clean up all resources
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manipulated by the factory. It it typically called at script
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termination.
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"""
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pass
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def pin(self, spec):
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"""
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Creates an instance of a :class:`Pin` descendent representing the
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specified pin.
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.. warning::
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Descendents must ensure that pin instances representing the same
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hardware are identical; i.e. two separate invocations of
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:meth:`pin` for the same pin specification must return the same
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object.
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"""
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raise PinGPIOUnsupported("GPIO not supported by this pin factory")
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def pin_address(self, spec):
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"""
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Returns the address that a pin *would* have if constructed from the
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given *spec*.
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This unusual method is used by the pin reservation system to check
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for conflicts *prior* to pin construction; with most implementations,
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pin construction implicitly alters the state of the pin (e.g. setting
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it to an input). This allows pin reservation to take place without
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affecting the state of other components.
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"""
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raise NotImplementedError
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def spi(self, **spi_args):
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"""
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Returns an instance of an :class:`SPI` interface, for the specified SPI
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*port* and *device*, or for the specified pins (*clock_pin*,
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*mosi_pin*, *miso_pin*, and *select_pin*). Only one of the schemes can
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be used; attempting to mix *port* and *device* with pin numbers will
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raise :exc:`SPIBadArgs`.
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"""
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raise PinSPIUnsupported('SPI not supported by this pin factory')
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def _get_address(self):
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raise NotImplementedError
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address = property(
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lambda self: self._get_address(),
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doc="""\
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Returns a tuple of strings representing the address of the factory.
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For the Pi itself this is a tuple of one string representing the Pi's
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address (e.g. "localhost"). Expander chips can return a tuple appending
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whatever string they require to uniquely identify the expander chip
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amongst all factories in the system.
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.. note::
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This property *must* return an immutable object capable of being
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used as a dictionary key.
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""")
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def _get_pi_info(self):
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return None
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pi_info = property(
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lambda self: self._get_pi_info(),
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doc="""\
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Returns a :class:`PiBoardInfo` instance representing the Pi that
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instances generated by this factory will be attached to.
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If the pins represented by this class are not *directly* attached to a
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Pi (e.g. the pin is attached to a board attached to the Pi, or the pins
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are not on a Pi at all), this may return ``None``.
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""")
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class Pin(object):
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"""
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Abstract base class representing a GPIO pin or a pin from an IO extender.
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Abstract base class representing a pin attached to some form of controller,
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be it GPIO, SPI, ADC, etc.
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Descendents should override property getters and setters to accurately
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represent the capabilities of pins. The following functions *must* be
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overridden:
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* :meth:`_get_address`
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* :meth:`_get_function`
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* :meth:`_set_function`
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* :meth:`_get_state`
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@@ -39,6 +133,8 @@ class Pin(object):
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The following functions *may* be overridden if applicable:
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* :meth:`close`
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* :meth:`output_with_state`
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* :meth:`input_with_pull`
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* :meth:`_set_state`
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* :meth:`_get_frequency`
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* :meth:`_set_frequency`
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@@ -50,20 +146,10 @@ class Pin(object):
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* :meth:`_set_edges`
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* :meth:`_get_when_changed`
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* :meth:`_set_when_changed`
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* :meth:`pi_info`
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* :meth:`output_with_state`
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* :meth:`input_with_pull`
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.. warning::
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Descendents must ensure that pin instances representing the same
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physical hardware are identical, right down to object identity. The
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framework relies on this to correctly clean up resources at interpreter
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shutdown.
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"""
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def __repr__(self):
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return "Abstract pin"
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return self.address[-1]
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def close(self):
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"""
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@@ -105,6 +191,18 @@ class Pin(object):
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self.function = 'input'
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self.pull = pull
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def _get_address(self):
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raise NotImplementedError
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address = property(
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lambda self: self._get_address(),
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doc="""\
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The address of the pin. This property is a tuple of strings constructed
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from the owning factory's address with the unique address of the pin
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appended to it. The tuple as a whole uniquely identifies the pin
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amongst all pins attached to the system.
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""")
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def _get_function(self):
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return "input"
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@@ -140,10 +238,19 @@ class Pin(object):
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doc="""\
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The state of the pin. This is 0 for low, and 1 for high. As a low level
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view of the pin, no swapping is performed in the case of pull ups (see
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:attr:`pull` for more information).
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:attr:`pull` for more information):
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If PWM is currently active (when :attr:`frequency` is not ``None``),
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this represents the PWM duty cycle as a value between 0.0 and 1.0.
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.. code-block:: text
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HIGH - - - - > ,----------------------
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|
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|
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LOW ----------------'
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Descendents which implement analog, or analog-like capabilities can
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return values between 0 and 1. For example, pins implementing PWM
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(where :attr:`frequency` is not ``None``) return a value between 0.0
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and 1.0 representing the current PWM duty cycle.
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If a pin is currently configured for input, and an attempt is made to
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set this attribute, :exc:`PinSetInput` will be raised. If an invalid
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@@ -205,6 +312,26 @@ class Pin(object):
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detection, measured in seconds. If bounce detection is not currently in
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use, this is ``None``.
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For example, if :attr:`edge` is currently "rising", :attr:`bounce` is
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currently 5/1000 (5ms), then the waveform below will only fire
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:attr:`when_changed` on two occasions despite there being three rising
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edges:
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.. code-block:: text
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TIME 0...1...2...3...4...5...6...7...8...9...10..11..12 ms
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bounce elimination |===================| |==============
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HIGH - - - - > ,--. ,--------------. ,--.
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| | | | | |
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| | | | | |
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LOW ----------------' `-' `-' `-----------
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: :
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: :
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when_changed when_changed
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fires fires
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If the pin does not support edge detection, attempts to set this
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property will raise :exc:`PinEdgeDetectUnsupported`. If the pin
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supports edge detection, the class must implement bounce detection,
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@@ -223,7 +350,18 @@ class Pin(object):
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doc="""\
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The edge that will trigger execution of the function or bound method
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assigned to :attr:`when_changed`. This can be one of the strings
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"both" (the default), "rising", "falling", or "none".
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"both" (the default), "rising", "falling", or "none":
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.. code-block:: text
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HIGH - - - - > ,--------------.
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| |
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| |
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LOW --------------------' `--------------
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: :
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: :
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Fires when_changed "both" "both"
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when edges is ... "rising" "falling"
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If the pin does not support edge detection, attempts to set this
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property will raise :exc:`PinEdgeDetectUnsupported`.
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@@ -247,48 +385,300 @@ class Pin(object):
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property will raise :exc:`PinEdgeDetectUnsupported`.
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""")
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@classmethod
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def pi_info(cls):
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"""
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Returns a :class:`PiBoardInfo` instance representing the Pi that
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instances of this pin class will be attached to.
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If the pins represented by this class are not *directly* attached to a
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Pi (e.g. the pin is attached to a board attached to the Pi, or the pins
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are not on a Pi at all), this may return ``None``.
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"""
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return None
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class LocalPin(Pin):
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class SPI(object):
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"""
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Abstract base class representing pins attached locally to a Pi. This forms
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the base class for local-only pin interfaces (:class:`RPiGPIOPin`,
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:class:`RPIOPin`, and :class:`NativePin`).
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Abstract interface for `Serial Peripheral Interface`_ (SPI) implementations.
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Descendents *must* override the following:
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* :meth:`transfer`
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* :meth:`_get_clock_mode`
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Descendents *may* override the following methods:
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* :meth:`read`
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* :meth:`write`
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* :meth:`_set_clock_mode`
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* :meth:`_get_lsb_first`
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* :meth:`_set_lsb_first`
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* :meth:`_get_select_high`
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* :meth:`_set_select_high`
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* :meth:`_get_bits_per_word`
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* :meth:`_set_bits_per_word`
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.. _Serial Peripheral Interface: https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus
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"""
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_PI_REVISION = None
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@classmethod
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def pi_info(cls):
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def read(self, n):
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"""
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Returns a :class:`PiBoardInfo` instance representing the local Pi.
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The Pi's revision is determined by reading :file:`/proc/cpuinfo`. If
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no valid revision is found, returns ``None``.
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"""
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# Cache the result as we can reasonably assume it won't change during
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# runtime (this is LocalPin after all; descendents that deal with
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# remote Pis should inherit from Pin instead)
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if cls._PI_REVISION is None:
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with io.open('/proc/cpuinfo', 'r') as f:
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for line in f:
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if line.startswith('Revision'):
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revision = line.split(':')[1].strip().lower()
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overvolted = revision.startswith('100')
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if overvolted:
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revision = revision[-4:]
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cls._PI_REVISION = revision
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break
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if cls._PI_REVISION is None:
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return None # something weird going on
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return pi_info(cls._PI_REVISION)
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Read *n* words of data from the SPI interface, returning them as a
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sequence of unsigned ints, each no larger than the configured
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:attr:`bits_per_word` of the interface.
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This method is typically used with read-only devices that feature
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half-duplex communication. See :meth:`transfer` for full duplex
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communication.
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"""
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return self.transfer((0,) * n)
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def write(self, data):
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"""
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Write *data* to the SPI interface. *data* must be a sequence of
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unsigned integer words each of which will fit within the configured
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:attr:`bits_per_word` of the interface. The method returns the number
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of words written to the interface (which may be less than or equal to
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the length of *data*).
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This method is typically used with write-only devices that feature
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half-duplex communication. See :meth:`transfer` for full duplex
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communication.
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"""
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return len(self.transfer(data))
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def transfer(self, data):
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"""
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Write *data* to the SPI interface. *data* must be a sequence of
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unsigned integer words each of which will fit within the configured
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:attr:`bits_per_word` of the interface. The method returns the sequence
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of words read from the interface while writing occurred (full duplex
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communication).
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The length of the sequence returned dictates the number of words of
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*data* written to the interface. Each word in the returned sequence
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will be an unsigned integer no larger than the configured
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:attr:`bits_per_word` of the interface.
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"""
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raise NotImplementedError
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@property
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def clock_polarity(self):
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"""
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The polarity of the SPI clock pin. If this is ``False`` (the default),
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the clock pin will idle low, and pulse high. Setting this to ``True``
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will cause the clock pin to idle high, and pulse low. On many data
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sheets this is documented as the CPOL value.
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The following diagram illustrates the waveform when
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:attr:`clock_polarity` is ``False`` (the default), equivalent to CPOL
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0:
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.. code-block:: text
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on on on on on on on
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,---. ,---. ,---. ,---. ,---. ,---. ,---.
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CLK | | | | | | | | | | | | | |
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| | | | | | | | | | | | | |
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------' `---' `---' `---' `---' `---' `---' `------
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idle off off off off off off idle
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|
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The following diagram illustrates the waveform when
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:attr:`clock_polarity` is ``True``, equivalent to CPOL 1:
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.. code-block:: text
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idle off off off off off off idle
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------. ,---. ,---. ,---. ,---. ,---. ,---. ,------
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| | | | | | | | | | | | | |
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CLK | | | | | | | | | | | | | |
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`---' `---' `---' `---' `---' `---' `---'
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on on on on on on on
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"""
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return bool(self.clock_mode & 2)
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@clock_polarity.setter
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def clock_polarity(self, value):
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self.clock_mode = self.clock_mode & (~2) | (bool(value) << 1)
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@property
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def clock_phase(self):
|
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"""
|
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The phase of the SPI clock pin. If this is ``False`` (the default),
|
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data will be read from the MISO pin when the clock pin activates.
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Setting this to ``True`` will cause data to be read from the MISO pin
|
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when the clock pin deactivates. On many data sheets this is documented
|
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as the CPHA value. Whether the clock edge is rising or falling when the
|
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clock is considered activated is controlled by the
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:attr:`clock_polarity` attribute (corresponding to CPOL).
|
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|
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The following diagram indicates when data is read when
|
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:attr:`clock_polarity` is ``False``, and :attr:`clock_phase` is
|
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``False`` (the default), equivalent to CPHA 0:
|
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|
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.. code-block:: text
|
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|
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,---. ,---. ,---. ,---. ,---. ,---. ,---.
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CLK | | | | | | | | | | | | | |
|
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| | | | | | | | | | | | | |
|
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----' `---' `---' `---' `---' `---' `---' `-------
|
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: : : : : : :
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MISO---. ,---. ,---. ,---. ,---. ,---. ,---.
|
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/ \ / \ / \ / \ / \ / \ / \\
|
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-{ Bit X Bit X Bit X Bit X Bit X Bit X Bit }------
|
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\ / \ / \ / \ / \ / \ / \ /
|
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`---' `---' `---' `---' `---' `---' `---'
|
||||
|
||||
The following diagram indicates when data is read when
|
||||
:attr:`clock_polarity` is ``False``, but :attr:`clock_phase` is
|
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``True``, equivalent to CPHA 1:
|
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|
||||
.. code-block:: text
|
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|
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,---. ,---. ,---. ,---. ,---. ,---. ,---.
|
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CLK | | | | | | | | | | | | | |
|
||||
| | | | | | | | | | | | | |
|
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----' `---' `---' `---' `---' `---' `---' `-------
|
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: : : : : : :
|
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MISO ,---. ,---. ,---. ,---. ,---. ,---. ,---.
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/ \ / \ / \ / \ / \ / \ / \\
|
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-----{ Bit X Bit X Bit X Bit X Bit X Bit X Bit }--
|
||||
\ / \ / \ / \ / \ / \ / \ /
|
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`---' `---' `---' `---' `---' `---' `---'
|
||||
"""
|
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return bool(self.clock_mode & 1)
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|
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@clock_phase.setter
|
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def clock_phase(self, value):
|
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self.clock_mode = self.clock_mode & (~1) | bool(value)
|
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|
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def _get_clock_mode(self):
|
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raise NotImplementedError
|
||||
|
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def _set_clock_mode(self, value):
|
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raise SPIFixedClockMode("clock_mode cannot be changed on %r" % self)
|
||||
|
||||
clock_mode = property(
|
||||
lambda self: self._get_clock_mode(),
|
||||
lambda self, value: self._set_clock_mode(value),
|
||||
doc="""\
|
||||
Presents a value representing the :attr:`clock_polarity` and
|
||||
:attr:`clock_phase` attributes combined according to the following
|
||||
table:
|
||||
|
||||
+------+-----------------+--------------+
|
||||
| mode | polarity (CPOL) | phase (CPHA) |
|
||||
+======+=================+==============+
|
||||
| 0 | False | False |
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||||
| 1 | False | True |
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||||
| 2 | True | False |
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||||
| 3 | True | True |
|
||||
+------+-----------------+--------------+
|
||||
|
||||
Adjusting this value adjusts both the :attr:`clock_polarity` and
|
||||
:attr:`clock_phase` attributes simultaneously.
|
||||
""")
|
||||
|
||||
def _get_lsb_first(self):
|
||||
return False
|
||||
|
||||
def _set_lsb_first(self, value):
|
||||
raise SPIFixedBitOrder("lsb_first cannot be changed on %r" % self)
|
||||
|
||||
lsb_first = property(
|
||||
lambda self: self._get_lsb_first(),
|
||||
lambda self, value: self._set_lsb_first(value),
|
||||
doc="""\
|
||||
Controls whether words are read and written LSB in (Least Significant
|
||||
Bit first) order. The default is ``False`` indicating that words are
|
||||
read and written in MSB (Most Significant Bit first) order.
|
||||
Effectively, this controls the `Bit endianness`_ of the connection.
|
||||
|
||||
The following diagram shows the a word containing the number 5 (binary
|
||||
0101) transmitted on MISO with :attr:`bits_per_word` set to 4, and
|
||||
:attr:`clock_mode` set to 0, when :attr:`lsb_first` is ``False`` (the
|
||||
default):
|
||||
|
||||
.. code-block:: text
|
||||
|
||||
,---. ,---. ,---. ,---.
|
||||
CLK | | | | | | | |
|
||||
| | | | | | | |
|
||||
----' `---' `---' `---' `-----
|
||||
: ,-------. : ,-------.
|
||||
MISO: | : | : | : |
|
||||
: | : | : | : |
|
||||
----------' : `-------' : `----
|
||||
: : : :
|
||||
MSB LSB
|
||||
|
||||
And now with :attr:`lsb_first` set to ``True`` (and all other
|
||||
parameters the same):
|
||||
|
||||
.. code-block:: text
|
||||
|
||||
,---. ,---. ,---. ,---.
|
||||
CLK | | | | | | | |
|
||||
| | | | | | | |
|
||||
----' `---' `---' `---' `-----
|
||||
,-------. : ,-------. :
|
||||
MISO: | : | : | :
|
||||
| : | : | : | :
|
||||
--' : `-------' : `-----------
|
||||
: : : :
|
||||
LSB MSB
|
||||
|
||||
.. _Bit endianness: https://en.wikipedia.org/wiki/Endianness#Bit_endianness
|
||||
""")
|
||||
|
||||
def _get_select_high(self):
|
||||
return False
|
||||
|
||||
def _set_select_high(self, value):
|
||||
raise SPIFixedSelect("select_high cannot be changed on %r" % self)
|
||||
|
||||
select_high = property(
|
||||
lambda self: self._get_select_high(),
|
||||
lambda self, value: self._set_select_high(value),
|
||||
doc="""\
|
||||
If ``False`` (the default), the chip select line is considered active
|
||||
when it is pulled low. When set to ``True``, the chip select line is
|
||||
considered active when it is driven high.
|
||||
|
||||
The following diagram shows the waveform of the chip select line, and
|
||||
the clock when :attr:`clock_polarity` is ``False``, and
|
||||
:attr:`select_high` is ``False`` (the default):
|
||||
|
||||
.. code-block:: text
|
||||
|
||||
---. ,------
|
||||
__ | |
|
||||
CS | chip is selected, and will react to clock | idle
|
||||
`-----------------------------------------------------'
|
||||
|
||||
,---. ,---. ,---. ,---. ,---. ,---. ,---.
|
||||
CLK | | | | | | | | | | | | | |
|
||||
| | | | | | | | | | | | | |
|
||||
----' `---' `---' `---' `---' `---' `---' `-------
|
||||
|
||||
And when :attr:`select_high` is ``True``:
|
||||
|
||||
.. code-block:: text
|
||||
|
||||
,-----------------------------------------------------.
|
||||
CS | chip is selected, and will react to clock | idle
|
||||
| |
|
||||
---' `------
|
||||
|
||||
,---. ,---. ,---. ,---. ,---. ,---. ,---.
|
||||
CLK | | | | | | | | | | | | | |
|
||||
| | | | | | | | | | | | | |
|
||||
----' `---' `---' `---' `---' `---' `---' `-------
|
||||
""")
|
||||
|
||||
def _get_bits_per_word(self):
|
||||
return 8
|
||||
|
||||
def _set_bits_per_word(self, value):
|
||||
raise SPIFixedWordSize("bits_per_word cannot be changed on %r" % self)
|
||||
|
||||
bits_per_word = property(
|
||||
lambda self: self._get_bits_per_word(),
|
||||
lambda self, value: self._set_bits_per_word(value),
|
||||
doc="""\
|
||||
Controls the number of bits that make up a word, and thus where the
|
||||
word boundaries appear in the data stream, and the maximum value of a
|
||||
word. Defaults to 8 meaning that words are effectively bytes.
|
||||
|
||||
Several implementations do not support non-byte-sized words.
|
||||
""")
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user