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:

Board pins are identified by their string name:

g = pyb.Pin('GP9', af=0, mode=pyb.Pin.IN, type=pyb.Pin.STD, strength=pyb.Pin.S2MA)

You can also configure the Pin to generate interrupts. For instance:

def pincb(pin):
    print(pin.name())

pin_int = pyb.Pin('GP10', af=0, mode=Pin.IN, type=pyb.Pin.STD_PD, strength=pyb.Pin.S2MA)
pin_int.callback (mode=pyb.Pin.INT_RISING, handler=pincb)
# the callback can be triggered manually
pin_int.callback()()
# to disable the callback
pin_int.callback().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 pyb.Pin(name, ...)

Create a new Pin object associated with the name. If additional arguments are given, they are used to initialise the pin. See pin.init().

Methods

pin.init(af, mode, type, strength)

Initialise the pin:

  • af 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.

  • mode can be one of:

    • Pin.OUT - no pull up or down resistors.
    • Pin.IN - enable the pull-up resistor.

  • type can be one of:

    • Pin.STD - push-pull pin.
    • Pin.STD_PU - push-pull pin with pull-up resistor.
    • Pin.STD_PD - push-pull pin with pull-down resistor.
    • Pin.OD - open drain pin.
    • Pin.OD_PU - open drain pin with pull-up resistor.
    • Pin.OD_PD - open drain pin with pull-down resistor.

  • strength can be one of:

    • Pin.S2MA - 2mA drive capability.
    • Pin.S4MA - 4mA drive capability.
    • Pin.S6MA - 6mA drive capability.

Returns: None.

pin.high()

Set the pin to a high logic level.

pin.low()

Set the pin to a low logic level.

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.
pin.name()

Get the pin name.

pin.toggle()

Toggle the value of the pin.

pin.info()

Return a 5-tuple with the configuration of the pin: (name, alternate-function, mode, type, strength)

Warning

This method cannot be called within a callback (interrupt-context) because it needs to allocate memory to return the tuple and memory allocations are disabled while interrupts are being serviced.

pin.callback(*, mode, priority=1, handler=None, wakes=pyb.Sleep.ACTIVE)

Create a callback to be triggered when the input level at the pin changes.

  • mode configures the pin level which can generate an interrupt. Possible values are:

    • Pin.INT_FALLING interrupt on falling edge.
    • Pin.INT_RISING interrupt on rising edge.
    • Pin.INT_RISING_FALLING interrupt on rising and falling edge.
    • Pin.INT_LOW_LEVEL interrupt on low level.
    • Pin.INT_HIGH_LEVEL interrupt on high level.

  • 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 wakes=pyb.Sleep.ACTIVE any pin can wake the board.
    • If wakes=pyb.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 pyb.Sleep.SUSPENDED wake source will have effect.
    • If wakes=pyb.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 pyb.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.

Constants

Pin.IN

input pin mode

Pin.OUT

output pin mode

Pin.STD

push-pull pin type

Pin.STD_PU

push-pull pin with internall pull-up resistor

Pin.STD_PD

push-pull pin with internall pull-down resistor

Pin.OD

open-drain pin

Pin.OD_PU

open-drain pin with pull-up resistor

Pin.OD_PD

open-drain pin with pull-down resistor

Pin.INT_FALLING

interrupt on falling edge

Pin.INT_RISING

interrupt on rising edge

Pin.INT_RISING_FALLING

interrupt on rising and falling edge

Pin.INT_LOW_LEVEL

interrupt on low level

Pin.INT_HIGH_LEVEL

interrupt on high level

Pin.S2MA

2mA drive strength

Pin.S4MA

4mA drive strength

Pin.S6MA

6mA drive strength