.. currentmodule:: gpiozero

As of release 1.1, the GPIO Zero library can be roughly divided into two things: pins and the devices that are connected to them. The majority of the documentation focuses on devices as pins are below the level that most users are concerned with. However, some users may wish to take advantage of the capabilities of alternative GPIO implementations or (in future) use GPIO extender chips. This is the purpose of the pins portion of the library.

When you construct a device, you pass in a GPIO pin number. However, what the library actually expects is a :class:`Pin` implementation. If it finds a simple integer number instead, it uses one of the following classes to provide the :class:`Pin` implementation (classes are listed in favoured order):

1. :class:`gpiozero.pins.rpigpio.RPiGPIOPin`
2. :class:`gpiozero.pins.rpio.RPIOPin`
3. :class:`gpiozero.pins.pigpiod.PiGPIOPin`
4. :class:`gpiozero.pins.native.NativePin`

You can change the default pin implementation by over-writing the DefaultPin global in the devices module like so:

from gpiozero.pins.native import NativePin
import gpiozero.devices
# Force the default pin implementation to be NativePin
gpiozero.devices.DefaultPin = NativePin

from gpiozero import LED

# This will now use NativePin instead of RPiGPIOPin
led = LED(16)

Alternatively, instead of passing an integer to the device constructor, you can pass a :class:`Pin` object itself:

from gpiozero.pins.native import NativePin
from gpiozero import LED

led = LED(NativePin(16))

This is particularly useful with implementations that can take extra parameters such as :class:`PiGPIOPin` which can address pins on remote machines:

from gpiozero.pins.pigpiod import PiGPIOPin
from gpiozero import LED

led = LED(PiGPIOPin(16, host='my_other_pi'))

In future, this separation of pins and devices should also permit the library to utilize pins that are part of IO extender chips. For example:

from gpiozero import IOExtender, LED

ext = IOExtender()
led = LED(ext.pins[0])
led.on()

.. currentmodule:: gpiozero.pins.rpigpio

.. autoclass:: RPiGPIOPin

.. currentmodule:: gpiozero.pins.rpio

.. autoclass:: RPIOPin

.. currentmodule:: gpiozero.pins.pigpiod

.. autoclass:: PiGPIOPin

.. currentmodule:: gpiozero.pins.native

.. autoclass:: NativePin

.. autoclass:: Pin
    :members: