.. _machine.Pin:
class Pin -- control I/O pins
=============================
A pin is the basic object to control I/O pins. It has methods to set
the mode of the pin (input, output, etc) and methods to get and set the
digital logic level. For analog control of a pin, see the ADC class.
Usage Model:
.. only:: port_wipy
Board pins are identified by their string id::
from machine import Pin
g = machine.Pin('GP9', mode=Pin.OUT, pull=None, drive=Pin.MED_POWER, alt=-1)
You can also configure the Pin to generate interrupts. For instance::
from machine import Pin
def pincb(pin):
print(pin.id())
pin_int = Pin('GP10', mode=Pin.IN, pull=Pin.PULL_DOWN)
pin_int.irq(mode=Pin.IRQ_RISING, handler=pincb)
# the callback can be triggered manually
pin_int.irq()()
# to disable the callback
pin_int.irq().disable()
Now every time a falling edge is seen on the gpio pin, the callback will be
executed. Caution: mechanical push buttons have "bounce" and pushing or
releasing a switch will often generate multiple edges.
See: http://www.eng.utah.edu/~cs5780/debouncing.pdf for a detailed
explanation, along with various techniques for debouncing.
All pin objects go through the pin mapper to come up with one of the
gpio pins.
Constructors
------------
.. class:: machine.Pin(id, ...)
Create a new Pin object associated with the id. If additional arguments are given,
they are used to initialise the pin. See :meth:`pin.init`.
Methods
-------
.. only:: port_wipy
.. method:: pin.init(mode, pull, \*, drive, alt)
Initialise the pin:
- ``mode`` can be one of:
- ``Pin.IN`` - input pin.
- ``Pin.OUT`` - output pin in push-pull mode.
- ``Pin.OPEN_DRAIN`` - output pin in open-drain mode.
- ``Pin.ALT`` - pin mapped to an alternate function.
- ``Pin.ALT_OPEN_DRAIN`` - pin mapped to an alternate function in open-drain mode.
- ``pull`` can be one of:
- ``None`` - no pull up or down resistor.
- ``Pin.PULL_UP`` - pull up resistor enabled.
- ``Pin.PULL_DOWN`` - pull down resitor enabled.
- ``drive`` can be one of:
- ``Pin.LOW_POWER`` - 2mA drive capability.
- ``Pin.MED_POWER`` - 4mA drive capability.
- ``Pin.HIGH_POWER`` - 6mA drive capability.
- ``alt`` is the number of the alternate function. Please refer to the
`pinout and alternate functions table. <https://raw.githubusercontent.com/wipy/wipy/master/docs/PinOUT.png>`_
for the specific alternate functions that each pin supports.
Returns: ``None``.
.. method:: pin.id()
Get the pin id.
.. method:: pin.value([value])
Get or set the digital logic level of the pin:
- With no argument, return 0 or 1 depending on the logic level of the pin.
- With ``value`` given, set the logic level of the pin. ``value`` can be
anything that converts to a boolean. If it converts to ``True``, the pin
is set high, otherwise it is set low.
.. method:: pin.alt_list()
Returns a list of the alternate functions supported by the pin. List items are
a tuple of the form: ``('ALT_FUN_NAME', ALT_FUN_INDEX)``
.. only:: port_wipy
.. method:: pin([value])
Pin objects are callable. The call method provides a (fast) shortcut to set and get the value of the pin.
See **pin.value** for more details.
.. method:: pin.toggle()
Toggle the value of the pin.
.. method:: pin.mode([mode])
Get or set the pin mode.
.. method:: pin.pull([pull])
Get or set the pin pull.
.. method:: pin.drive([drive])
Get or set the pin drive strength.
.. method:: pin.irq(\*, trigger, priority=1, handler=None, wake=None)
Create a callback to be triggered when the input level at the pin changes.
- ``trigger`` configures the pin level which can generate an interrupt. Possible values are:
- ``Pin.IRQ_FALLING`` interrupt on falling edge.
- ``Pin.IRQ_RISING`` interrupt on rising edge.
- ``Pin.IRQ_LOW_LEVEL`` interrupt on low level.
- ``Pin.IRQ_HIGH_LEVEL`` interrupt on high level.
The values can be *ORed* together, for instance mode=Pin.IRQ_FALLING | Pin.IRQ_RISING
- ``priority`` level of the interrupt. Can take values in the range 1-7.
Higher values represent higher priorities.
- ``handler`` is an optional function to be called when new characters arrive.
- ``wakes`` selects the power mode in which this interrupt can wake up the
board. Please note:
- If ``wake_from=machine.Sleep.ACTIVE`` any pin can wake the board.
- If ``wake_from=machine.Sleep.SUSPENDED`` pins ``GP2``, ``GP4``, ``GP10``,
``GP11``, GP17`` or ``GP24`` can wake the board. Note that only 1
of this pins can be enabled as a wake source at the same time, so, only
the last enabled pin as a ``machine.Sleep.SUSPENDED`` wake source will have effect.
- If ``wake_from=machine.Sleep.SUSPENDED`` pins ``GP2``, ``GP4``, ``GP10``,
``GP11``, ``GP17`` and ``GP24`` can wake the board. In this case all of the
6 pins can be enabled as a ``machine.Sleep.HIBERNATE`` wake source at the same time.
- Values can be ORed to make a pin generate interrupts in more than one power
mode.
Returns a callback object.
Attributes
----------
.. class:: Pin.board
Contains all ``Pin`` objects supported by the board. Examples::
Pin.board.GP25
led = Pin(Pin.board.GP25, mode=Pin.OUT)
Pin.board.GP2.alt_list()
Constants
---------
.. only:: port_wipy
.. data:: Pin.IN
.. data:: Pin.OUT
.. data:: Pin.OPEN_DRAIN
.. data:: Pin.ALT
.. data:: Pin.ALT_OPEN_DRAIN
Selects the pin mode.
.. data:: Pin.PULL_UP
.. data:: Pin.PULL_DOWN
Selectes the wether there's pull up/down resistor.
.. data:: Pin.LOW_POWER
.. data:: Pin.MED_POWER
.. data:: Pin.HIGH_POWER
Selects the drive strength.
.. data:: Pin.IRQ_FALLING
.. data:: Pin.IRQ_RISING
.. data:: Pin.IRQ_LOW_LEVEL
.. data:: Pin.IRQ_HIGH_LEVEL
Selects the IRQ trigger type.