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0838965796
Adds when_held event hook to Button (via extension of the EventsMixin class). Also fixes some minor notes and activates codecov coverage tracking.
128 lines
3.5 KiB
ReStructuredText
128 lines
3.5 KiB
ReStructuredText
====
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Pins
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====
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.. currentmodule:: gpiozero
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As of release 1.1, the GPIO Zero library can be roughly divided into two
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things: pins and the devices that are connected to them. The majority of the
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documentation focuses on devices as pins are below the level that most users
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are concerned with. However, some users may wish to take advantage of the
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capabilities of alternative GPIO implementations or (in future) use GPIO
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extender chips. This is the purpose of the pins portion of the library.
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When you construct a device, you pass in a GPIO pin number. However, what the
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library actually expects is a :class:`Pin` implementation. If it finds a simple
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integer number instead, it uses one of the following classes to provide the
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:class:`Pin` implementation (classes are listed in favoured order):
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1. :class:`gpiozero.pins.rpigpio.RPiGPIOPin`
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2. :class:`gpiozero.pins.rpio.RPIOPin`
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3. :class:`gpiozero.pins.pigpiod.PiGPIOPin`
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4. :class:`gpiozero.pins.native.NativePin`
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You can change the default pin implementation by over-writing the
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``DefaultPin`` global in the ``devices`` module like so::
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from gpiozero.pins.native import NativePin
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import gpiozero.devices
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# Force the default pin implementation to be NativePin
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gpiozero.devices.DefaultPin = NativePin
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from gpiozero import LED
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# This will now use NativePin instead of RPiGPIOPin
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led = LED(16)
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Alternatively, instead of passing an integer to the device constructor, you
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can pass a :class:`Pin` object itself::
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from gpiozero.pins.native import NativePin
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from gpiozero import LED
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led = LED(NativePin(16))
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This is particularly useful with implementations that can take extra parameters
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such as :class:`~gpiozero.pins.pigpiod.PiGPIOPin` which can address pins on
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remote machines::
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from gpiozero.pins.pigpiod import PiGPIOPin
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from gpiozero import LED
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led = LED(PiGPIOPin(16, host='my_other_pi'))
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In future, this separation of pins and devices should also permit the library
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to utilize pins that are part of IO extender chips. For example::
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from gpiozero import IOExtender, LED
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ext = IOExtender()
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led = LED(ext.pins[0])
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led.on()
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.. warning::
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While the devices API is now considered stable and won't change in
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backwards incompatible ways, the pins API is *not* yet considered stable.
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It is potentially subject to change in future versions. We welcome any
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comments from testers!
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.. warning::
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The astute and mischievous reader may note that it is possible to mix pin
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implementations, e.g. using ``RPiGPIOPin`` for one pin, and ``NativePin``
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for another. This is unsupported, and if it results in your script
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crashing, your components failing, or your Raspberry Pi turning into an
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actual raspberry pie, you have only yourself to blame.
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RPiGPIOPin
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==========
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.. autoclass:: gpiozero.pins.rpigpio.RPiGPIOPin
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RPIOPin
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=======
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.. autoclass:: gpiozero.pins.rpio.RPIOPin
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PiGPIOPin
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=========
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.. autoclass:: gpiozero.pins.pigpiod.PiGPIOPin
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NativePin
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=========
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.. autoclass:: gpiozero.pins.native.NativePin
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Abstract Pin
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============
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.. autoclass:: Pin
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:members:
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Utilities
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=========
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The pins module also contains a database of information about the various
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revisions of Raspberry Pi. This is used internally to raise warnings when
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non-physical pins are used, or to raise exceptions when pull-downs are
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requested on pins with physical pull-up resistors attached. The following
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functions and classes can be used to query this database:
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.. autofunction:: pi_info
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.. autoclass:: PiBoardInfo
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.. autoclass:: PinInfo
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