.. currentmodule:: machine class Pin -- control I/O pins ============================= A pin is the basic object to control I/O pins (also known as GPIO - general-purpose input/output). 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(trigger=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. .. only:: port_esp8266 :: from machine import Pin # create an output pin on GPIO0 p0 = Pin(0, Pin.OUT) p0.value(0) p0.value(1) # create an input pin on GPIO2 p2 = Pin(2, Pin.IN, Pin.PULL_UP) print(p2.value()) 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. `_ for the specific alternate functions that each pin supports. Returns: ``None``. .. method:: Pin.id() Get the pin id. .. only:: port_esp8266 .. method:: Pin.init(mode, pull=None, \*, value) Initialise the pin: - `mode` can be one of: - ``Pin.IN`` - input pin. - ``Pin.OUT`` - output pin in push-pull mode. - `pull` can be one of: - ``None`` - no pull up or down resistor. - ``Pin.PULL_UP`` - pull up resistor enabled. - if `value` is given then it is the output value to set the pin if it is in output mode. .. 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([value]) Pin objects are callable. The call method provides a (fast) shortcut to set and get the value of the pin. See :func:`Pin.value` for more details. .. 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)`` Availability: WiPy. .. only:: port_wipy .. 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. .. only:: port_esp8266 .. method:: Pin.irq(\*, trigger, handler=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. The values can be OR'ed together to trigger on multiple events. - ``handler`` is an optional function to be called when the interrupt triggers. 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() Availability: WiPy. Constants --------- The following constants are used to configure the pin objects. Note that not all constants are available on all ports. .. data:: IN OUT OPEN_DRAIN ALT ALT_OPEN_DRAIN Selects the pin mode. .. data:: PULL_UP PULL_DOWN Selects the whether there is a pull up/down resistor. .. data:: LOW_POWER MED_POWER HIGH_POWER Selects the pin drive strength. .. data:: IRQ_FALLING IRQ_RISING IRQ_LOW_LEVEL IRQ_HIGH_LEVEL Selects the IRQ trigger type.