You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
248 lines
9.5 KiB
248 lines
9.5 KiB
.. currentmodule:: machine
|
|
.. _machine.Pin:
|
|
|
|
class Pin -- control I/O pins
|
|
=============================
|
|
|
|
A pin object is used to control I/O pins (also known as GPIO - general-purpose
|
|
input/output). Pin objects are commonly associated with a physical pin that can
|
|
drive an output voltage and read input voltages. The pin class has methods to set the mode of
|
|
the pin (IN, OUT, etc) and methods to get and set the digital logic level.
|
|
For analog control of a pin, see the :class:`ADC` class.
|
|
|
|
A pin object is constructed by using an identifier which unambiguously
|
|
specifies a certain I/O pin. The allowed forms of the identifier and the
|
|
physical pin that the identifier maps to are port-specific. Possibilities
|
|
for the identifier are an integer, a string or a tuple with port and pin
|
|
number.
|
|
|
|
Usage Model::
|
|
|
|
from machine import Pin
|
|
|
|
# create an output pin on pin #0
|
|
p0 = Pin(0, Pin.OUT)
|
|
|
|
# set the value low then high
|
|
p0.value(0)
|
|
p0.value(1)
|
|
|
|
# create an input pin on pin #2, with a pull up resistor
|
|
p2 = Pin(2, Pin.IN, Pin.PULL_UP)
|
|
|
|
# read and print the pin value
|
|
print(p2.value())
|
|
|
|
# reconfigure pin #0 in input mode
|
|
p0.mode(p0.IN)
|
|
|
|
# configure an irq callback
|
|
p0.irq(lambda p:print(p))
|
|
|
|
Constructors
|
|
------------
|
|
|
|
.. class:: Pin(id, mode=-1, pull=-1, \*, value, drive, alt)
|
|
|
|
Access the pin peripheral (GPIO pin) associated with the given ``id``. If
|
|
additional arguments are given in the constructor then they are used to initialise
|
|
the pin. Any settings that are not specified will remain in their previous state.
|
|
|
|
The arguments are:
|
|
|
|
- ``id`` is mandatory and can be an arbitrary object. Among possible value
|
|
types are: int (an internal Pin identifier), str (a Pin name), and tuple
|
|
(pair of [port, pin]).
|
|
|
|
- ``mode`` specifies the pin mode, which can be one of:
|
|
|
|
- ``Pin.IN`` - Pin is configured for input. If viewed as an output the pin
|
|
is in high-impedance state.
|
|
|
|
- ``Pin.OUT`` - Pin is configured for (normal) output.
|
|
|
|
- ``Pin.OPEN_DRAIN`` - Pin is configured for open-drain output. Open-drain
|
|
output works in the following way: if the output value is set to 0 the pin
|
|
is active at a low level; if the output value is 1 the pin is in a high-impedance
|
|
state. Not all ports implement this mode, or some might only on certain pins.
|
|
|
|
- ``Pin.ALT`` - Pin is configured to perform an alternative function, which is
|
|
port specific. For a pin configured in such a way any other Pin methods
|
|
(except :meth:`Pin.init`) are not applicable (calling them will lead to undefined,
|
|
or a hardware-specific, result). Not all ports implement this mode.
|
|
|
|
- ``Pin.ALT_OPEN_DRAIN`` - The Same as ``Pin.ALT``, but the pin is configured as
|
|
open-drain. Not all ports implement this mode.
|
|
|
|
- ``pull`` specifies if the pin has a (weak) pull resistor attached, and can be
|
|
one of:
|
|
|
|
- ``None`` - No pull up or down resistor.
|
|
- ``Pin.PULL_UP`` - Pull up resistor enabled.
|
|
- ``Pin.PULL_DOWN`` - Pull down resistor enabled.
|
|
|
|
- ``value`` is valid only for Pin.OUT and Pin.OPEN_DRAIN modes and specifies initial
|
|
output pin value if given, otherwise the state of the pin peripheral remains
|
|
unchanged.
|
|
|
|
- ``drive`` specifies the output power of the pin and can be one of: ``Pin.LOW_POWER``,
|
|
``Pin.MED_POWER`` or ``Pin.HIGH_POWER``. The actual current driving capabilities
|
|
are port dependent. Not all ports implement this argument.
|
|
|
|
- ``alt`` specifies an alternate function for the pin and the values it can take are
|
|
port dependent. This argument is valid only for ``Pin.ALT`` and ``Pin.ALT_OPEN_DRAIN``
|
|
modes. It may be used when a pin supports more than one alternate function. If only
|
|
one pin alternate function is supported the this argument is not required. Not all
|
|
ports implement this argument.
|
|
|
|
As specified above, the Pin class allows to set an alternate function for a particular
|
|
pin, but it does not specify any further operations on such a pin. Pins configured in
|
|
alternate-function mode are usually not used as GPIO but are instead driven by other
|
|
hardware peripherals. The only operation supported on such a pin is re-initialising,
|
|
by calling the constructor or :meth:`Pin.init` method. If a pin that is configured in
|
|
alternate-function mode is re-initialised with ``Pin.IN``, ``Pin.OUT``, or
|
|
``Pin.OPEN_DRAIN``, the alternate function will be removed from the pin.
|
|
|
|
Methods
|
|
-------
|
|
|
|
.. method:: Pin.init(mode=-1, pull=-1, \*, value, drive, alt)
|
|
|
|
Re-initialise the pin using the given parameters. Only those arguments that
|
|
are specified will be set. The rest of the pin peripheral state will remain
|
|
unchanged. See the constructor documentation for details of the arguments.
|
|
|
|
Returns ``None``.
|
|
|
|
.. method:: Pin.value([x])
|
|
|
|
This method allows to set and get the value of the pin, depending on whether
|
|
the argument ``x`` is supplied or not.
|
|
|
|
If the argument is omitted then this method gets the digital logic level of
|
|
the pin, returning 0 or 1 corresponding to low and high voltage signals
|
|
respectively. The behaviour of this method depends on the mode of the pin:
|
|
|
|
- ``Pin.IN`` - The method returns the actual input value currently present
|
|
on the pin.
|
|
- ``Pin.OUT`` - The behaviour and return value of the method is undefined.
|
|
- ``Pin.OPEN_DRAIN`` - If the pin is in state '0' then the behaviour and
|
|
return value of the method is undefined. Otherwise, if the pin is in
|
|
state '1', the method returns the actual input value currently present
|
|
on the pin.
|
|
|
|
If the argument is supplied then this method sets the digital logic level of
|
|
the pin. The argument ``x`` can be anything that converts to a boolean.
|
|
If it converts to ``True``, the pin is set to state '1', otherwise it is set
|
|
to state '0'. The behaviour of this method depends on the mode of the pin:
|
|
|
|
- ``Pin.IN`` - The value is stored in the output buffer for the pin. The
|
|
pin state does not change, it remains in the high-impedance state. The
|
|
stored value will become active on the pin as soon as it is changed to
|
|
``Pin.OUT`` or ``Pin.OPEN_DRAIN`` mode.
|
|
- ``Pin.OUT`` - The output buffer is set to the given value immediately.
|
|
- ``Pin.OPEN_DRAIN`` - If the value is '0' the pin is set to a low voltage
|
|
state. Otherwise the pin is set to high-impedance state.
|
|
|
|
When setting the value this method returns ``None``.
|
|
|
|
.. method:: Pin.__call__([x])
|
|
|
|
Pin objects are callable. The call method provides a (fast) shortcut to set
|
|
and get the value of the pin. It is equivalent to Pin.value([x]).
|
|
See :meth:`Pin.value` for more details.
|
|
|
|
.. method:: Pin.on()
|
|
|
|
Set pin to "1" output level.
|
|
|
|
.. method:: Pin.off()
|
|
|
|
Set pin to "0" output level.
|
|
|
|
.. method:: Pin.mode([mode])
|
|
|
|
Get or set the pin mode.
|
|
See the constructor documentation for details of the ``mode`` argument.
|
|
|
|
.. method:: Pin.pull([pull])
|
|
|
|
Get or set the pin pull state.
|
|
See the constructor documentation for details of the ``pull`` argument.
|
|
|
|
.. method:: Pin.drive([drive])
|
|
|
|
Get or set the pin drive strength.
|
|
See the constructor documentation for details of the ``drive`` argument.
|
|
|
|
Not all ports implement this method.
|
|
|
|
Availability: WiPy.
|
|
|
|
.. method:: Pin.irq(handler=None, trigger=(Pin.IRQ_FALLING | Pin.IRQ_RISING), \*, priority=1, wake=None)
|
|
|
|
Configure an interrupt handler to be called when the trigger source of the
|
|
pin is active. If the pin mode is ``Pin.IN`` then the trigger source is
|
|
the external value on the pin. If the pin mode is ``Pin.OUT`` then the
|
|
trigger source is the output buffer of the pin. Otherwise, if the pin mode
|
|
is ``Pin.OPEN_DRAIN`` then the trigger source is the output buffer for
|
|
state '0' and the external pin value for state '1'.
|
|
|
|
The arguments are:
|
|
|
|
- ``handler`` is an optional function to be called when the interrupt
|
|
triggers.
|
|
|
|
- ``trigger`` configures the event 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.
|
|
|
|
These values can be OR'ed together to trigger on multiple events.
|
|
|
|
- ``priority`` sets the priority level of the interrupt. The values it
|
|
can take are port-specific, but higher values always represent higher
|
|
priorities.
|
|
|
|
- ``wake`` selects the power mode in which this interrupt can wake up the
|
|
system. It can be ``machine.IDLE``, ``machine.SLEEP`` or ``machine.DEEPSLEEP``.
|
|
These values can also be OR'ed together to make a pin generate interrupts in
|
|
more than one power mode.
|
|
|
|
This method returns a callback object.
|
|
|
|
Constants
|
|
---------
|
|
|
|
The following constants are used to configure the pin objects. Note that
|
|
not all constants are available on all ports.
|
|
|
|
.. data:: Pin.IN
|
|
Pin.OUT
|
|
Pin.OPEN_DRAIN
|
|
Pin.ALT
|
|
Pin.ALT_OPEN_DRAIN
|
|
|
|
Selects the pin mode.
|
|
|
|
.. data:: Pin.PULL_UP
|
|
Pin.PULL_DOWN
|
|
|
|
Selects whether there is a pull up/down resistor. Use the value
|
|
``None`` for no pull.
|
|
|
|
.. data:: Pin.LOW_POWER
|
|
Pin.MED_POWER
|
|
Pin.HIGH_POWER
|
|
|
|
Selects the pin drive strength.
|
|
|
|
.. data:: Pin.IRQ_FALLING
|
|
Pin.IRQ_RISING
|
|
Pin.IRQ_LOW_LEVEL
|
|
Pin.IRQ_HIGH_LEVEL
|
|
|
|
Selects the IRQ trigger type.
|
|
|