256 lines
7.8 KiB
ReStructuredText
256 lines
7.8 KiB
ReStructuredText
.. currentmodule:: machine
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class Pin -- control I/O pins
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=============================
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A pin is the basic object to control I/O pins (also known as GPIO -
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general-purpose input/output). It has methods to set
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the mode of the pin (input, output, etc) and methods to get and set the
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digital logic level. For analog control of a pin, see the ADC class.
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Usage Model:
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.. only:: port_wipy
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Board pins are identified by their string id::
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from machine import Pin
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g = machine.Pin('GP9', mode=Pin.OUT, pull=None, drive=Pin.MED_POWER, alt=-1)
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You can also configure the Pin to generate interrupts. For instance::
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from machine import Pin
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def pincb(pin):
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print(pin.id())
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pin_int = Pin('GP10', mode=Pin.IN, pull=Pin.PULL_DOWN)
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pin_int.irq(trigger=Pin.IRQ_RISING, handler=pincb)
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# the callback can be triggered manually
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pin_int.irq()()
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# to disable the callback
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pin_int.irq().disable()
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Now every time a falling edge is seen on the gpio pin, the callback will be
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executed. Caution: mechanical push buttons have "bounce" and pushing or
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releasing a switch will often generate multiple edges.
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See: http://www.eng.utah.edu/~cs5780/debouncing.pdf for a detailed
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explanation, along with various techniques for debouncing.
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All pin objects go through the pin mapper to come up with one of the
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gpio pins.
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.. only:: port_esp8266
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::
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from machine import Pin
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# create an output pin on GPIO0
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p0 = Pin(0, Pin.OUT)
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p0.value(0)
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p0.value(1)
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# create an input pin on GPIO2
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p2 = Pin(2, Pin.IN, Pin.PULL_UP)
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print(p2.value())
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Constructors
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------------
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.. class:: Pin(id, ...)
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Create a new Pin object associated with the id. If additional arguments are given,
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they are used to initialise the pin. See :meth:`Pin.init`.
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Methods
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-------
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.. only:: port_wipy
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.. method:: Pin.init(mode, pull, \*, drive, alt)
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Initialise the pin:
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- ``mode`` can be one of:
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- ``Pin.IN`` - input pin.
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- ``Pin.OUT`` - output pin in push-pull mode.
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- ``Pin.OPEN_DRAIN`` - output pin in open-drain mode.
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- ``Pin.ALT`` - pin mapped to an alternate function.
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- ``Pin.ALT_OPEN_DRAIN`` - pin mapped to an alternate function in open-drain mode.
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- ``pull`` can be one of:
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- ``None`` - no pull up or down resistor.
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- ``Pin.PULL_UP`` - pull up resistor enabled.
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- ``Pin.PULL_DOWN`` - pull down resistor enabled.
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- ``drive`` can be one of:
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- ``Pin.LOW_POWER`` - 2mA drive capability.
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- ``Pin.MED_POWER`` - 4mA drive capability.
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- ``Pin.HIGH_POWER`` - 6mA drive capability.
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- ``alt`` is the number of the alternate function. Please refer to the
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`pinout and alternate functions table. <https://raw.githubusercontent.com/wipy/wipy/master/docs/PinOUT.png>`_
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for the specific alternate functions that each pin supports.
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Returns: ``None``.
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.. method:: Pin.id()
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Get the pin id.
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.. only:: port_esp8266
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.. method:: Pin.init(mode, pull=None, \*, value)
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Initialise the pin:
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- `mode` can be one of:
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- ``Pin.IN`` - input pin.
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- ``Pin.OUT`` - output pin in push-pull mode.
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- `pull` can be one of:
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- ``None`` - no pull up or down resistor.
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- ``Pin.PULL_UP`` - pull up resistor enabled.
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- if `value` is given then it is the output value to set the pin
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if it is in output mode.
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.. method:: Pin.value([value])
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Get or set the digital logic level of the pin:
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- With no argument, return 0 or 1 depending on the logic level of the pin.
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- With ``value`` given, set the logic level of the pin. ``value`` can be
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anything that converts to a boolean. If it converts to ``True``, the pin
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is set high, otherwise it is set low.
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.. method:: Pin.__call__([value])
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Pin objects are callable. The call method provides a (fast) shortcut to set and get the value of the pin.
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See :func:`Pin.value` for more details.
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.. method:: Pin.alt_list()
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Returns a list of the alternate functions supported by the pin. List items are
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a tuple of the form: ``('ALT_FUN_NAME', ALT_FUN_INDEX)``
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Availability: WiPy.
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.. only:: port_wipy
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.. method:: Pin.toggle()
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Toggle the value of the pin.
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.. method:: Pin.mode([mode])
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Get or set the pin mode.
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.. method:: Pin.pull([pull])
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Get or set the pin pull.
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.. method:: Pin.drive([drive])
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Get or set the pin drive strength.
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.. method:: Pin.irq(\*, trigger, priority=1, handler=None, wake=None)
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Create a callback to be triggered when the input level at the pin changes.
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- ``trigger`` configures the pin level which can generate an interrupt. Possible values are:
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- ``Pin.IRQ_FALLING`` interrupt on falling edge.
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- ``Pin.IRQ_RISING`` interrupt on rising edge.
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- ``Pin.IRQ_LOW_LEVEL`` interrupt on low level.
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- ``Pin.IRQ_HIGH_LEVEL`` interrupt on high level.
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The values can be *ORed* together, for instance mode=Pin.IRQ_FALLING | Pin.IRQ_RISING
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- ``priority`` level of the interrupt. Can take values in the range 1-7.
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Higher values represent higher priorities.
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- ``handler`` is an optional function to be called when new characters arrive.
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- ``wakes`` selects the power mode in which this interrupt can wake up the
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board. Please note:
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- If ``wake_from=machine.Sleep.ACTIVE`` any pin can wake the board.
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- If ``wake_from=machine.Sleep.SUSPENDED`` pins ``GP2``, ``GP4``, ``GP10``,
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``GP11``, GP17`` or ``GP24`` can wake the board. Note that only 1
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of this pins can be enabled as a wake source at the same time, so, only
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the last enabled pin as a ``machine.Sleep.SUSPENDED`` wake source will have effect.
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- If ``wake_from=machine.Sleep.SUSPENDED`` pins ``GP2``, ``GP4``, ``GP10``,
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``GP11``, ``GP17`` and ``GP24`` can wake the board. In this case all of the
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6 pins can be enabled as a ``machine.Sleep.HIBERNATE`` wake source at the same time.
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- Values can be ORed to make a pin generate interrupts in more than one power
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mode.
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Returns a callback object.
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.. only:: port_esp8266
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.. method:: Pin.irq(\*, trigger, handler=None)
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Create a callback to be triggered when the input level at the pin changes.
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- ``trigger`` configures the pin level which can generate an interrupt. Possible values are:
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- ``Pin.IRQ_FALLING`` interrupt on falling edge.
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- ``Pin.IRQ_RISING`` interrupt on rising edge.
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The values can be OR'ed together to trigger on multiple events.
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- ``handler`` is an optional function to be called when the interrupt triggers.
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Returns a callback object.
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Attributes
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----------
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.. class:: Pin.board
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Contains all ``Pin`` objects supported by the board. Examples::
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Pin.board.GP25
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led = Pin(Pin.board.GP25, mode=Pin.OUT)
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Pin.board.GP2.alt_list()
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Availability: WiPy.
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Constants
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---------
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The following constants are used to configure the pin objects. Note that
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not all constants are available on all ports.
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.. data:: Pin.IN
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Pin.OUT
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Pin.OPEN_DRAIN
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Pin.ALT
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Pin.ALT_OPEN_DRAIN
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Selects the pin mode.
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.. data:: Pin.PULL_UP
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Pin.PULL_DOWN
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Selects the whether there is a pull up/down resistor.
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.. data:: Pin.LOW_POWER
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Pin.MED_POWER
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Pin.HIGH_POWER
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Selects the pin drive strength.
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.. data:: Pin.IRQ_FALLING
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Pin.IRQ_RISING
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Pin.IRQ_LOW_LEVEL
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Pin.IRQ_HIGH_LEVEL
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Selects the IRQ trigger type.
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