.. _pyb.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_pyboard
All Board Pins are predefined as pyb.Pin.board.Name::
x1_pin = pyb.Pin.board.X1
g = pyb.Pin(pyb.Pin.board.X1, pyb.Pin.IN)
CPU pins which correspond to the board pins are available
as ``pyb.cpu.Name``. For the CPU pins, the names are the port letter
followed by the pin number. On the PYBv1.0, ``pyb.Pin.board.X1`` and
``pyb.Pin.cpu.B6`` are the same pin.
You can also use strings::
g = pyb.Pin('X1', pyb.Pin.OUT_PP)
Users can add their own names::
MyMapperDict = { 'LeftMotorDir' : pyb.Pin.cpu.C12 }
pyb.Pin.dict(MyMapperDict)
g = pyb.Pin("LeftMotorDir", pyb.Pin.OUT_OD)
and can query mappings::
pin = pyb.Pin("LeftMotorDir")
Users can also add their own mapping function::
def MyMapper(pin_name):
if pin_name == "LeftMotorDir":
return pyb.Pin.cpu.A0
pyb.Pin.mapper(MyMapper)
So, if you were to call: ``pyb.Pin("LeftMotorDir", pyb.Pin.OUT_PP)``
then ``"LeftMotorDir"`` is passed directly to the mapper function.
To summarise, the following order determines how things get mapped into
an ordinal pin number:
1. Directly specify a pin object
2. User supplied mapping function
3. User supplied mapping (object must be usable as a dictionary key)
4. Supply a string which matches a board pin
5. Supply a string which matches a CPU port/pin
You can set ``pyb.Pin.debug(True)`` to get some debug information about
how a particular object gets mapped to a pin.
When a pin has the ``Pin.PULL_UP`` or ``Pin.PULL_DOWN`` pull-mode enabled,
that pin has an effective 40k Ohm resistor pulling it to 3V3 or GND
respectively (except pin Y5 which has 11k Ohm resistors).
.. only:: port_wipy
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
------------
.. only:: port_pyboard
.. class:: pyb.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`.
.. only:: port_wipy
.. 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 :meth:`pin.init`.
.. only:: port_pyboard
Class methods
-------------
.. method:: Pin.af_list()
Returns an array of alternate functions available for this pin.
.. method:: Pin.debug([state])
Get or set the debugging state (``True`` or ``False`` for on or off).
.. method:: Pin.dict([dict])
Get or set the pin mapper dictionary.
.. method:: Pin.mapper([fun])
Get or set the pin mapper function.
Methods
-------
.. only:: port_pyboard
.. method:: pin.init(mode, pull=Pin.PULL_NONE, af=-1)
Initialise the pin:
- ``mode`` can be one of:
- ``Pin.IN`` - configure the pin for input;
- ``Pin.OUT_PP`` - configure the pin for output, with push-pull control;
- ``Pin.OUT_OD`` - configure the pin for output, with open-drain control;
- ``Pin.AF_PP`` - configure the pin for alternate function, pull-pull;
- ``Pin.AF_OD`` - configure the pin for alternate function, open-drain;
- ``Pin.ANALOG`` - configure the pin for analog.
- ``pull`` can be one of:
- ``Pin.PULL_NONE`` - no pull up or down resistors;
- ``Pin.PULL_UP`` - enable the pull-up resistor;
- ``Pin.PULL_DOWN`` - enable the pull-down resistor.
- when mode is ``Pin.AF_PP`` or ``Pin.AF_OD``, then af can be the index or name
of one of the alternate functions associated with a pin.
Returns: ``None``.
.. only:: port_wipy
.. method:: 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. <https://raw.githubusercontent.com/wipy/wipy/master/docs/PinOUT.png>`_
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``.
.. method:: pin.high()
Set the pin to a high logic level.
.. method:: pin.low()
Set the pin to a low logic level.
.. 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.
.. only:: port_pyboard
.. method:: pin.__str__()
Return a string describing the pin object.
.. method:: pin.af()
Returns the currently configured alternate-function of the pin. The
integer returned will match one of the allowed constants for the af
argument to the init function.
.. method:: pin.gpio()
Returns the base address of the GPIO block associated with this pin.
.. method:: pin.mode()
Returns the currently configured mode of the pin. The integer returned
will match one of the allowed constants for the mode argument to the init
function.
.. method:: pin.name()
Get the pin name.
.. only:: port_pyboard
.. method:: pin.names()
Returns the cpu and board names for this pin.
.. method:: pin.pin()
Get the pin number.
.. method:: pin.port()
Get the pin port.
.. method:: pin.pull()
Returns the currently configured pull of the pin. The integer returned
will match one of the allowed constants for the pull argument to the init
function.
.. only:: port_wipy
.. method:: pin.toggle()
Toggle the value of the pin.
.. method:: 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.
.. method:: 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
---------
.. only:: port_pyboard
.. data:: Pin.AF_OD
initialise the pin to alternate-function mode with an open-drain drive
.. data:: Pin.AF_PP
initialise the pin to alternate-function mode with a push-pull drive
.. data:: Pin.ANALOG
initialise the pin to analog mode
.. data:: Pin.IN
initialise the pin to input mode
.. data:: Pin.OUT_OD
initialise the pin to output mode with an open-drain drive
.. data:: Pin.OUT_PP
initialise the pin to output mode with a push-pull drive
.. data:: Pin.PULL_DOWN
enable the pull-down resistor on the pin
.. data:: Pin.PULL_NONE
don't enable any pull up or down resistors on the pin
.. data:: Pin.PULL_UP
enable the pull-up resistor on the pin
.. only:: port_wipy
.. data:: Pin.IN
input pin mode
.. data:: Pin.OUT
output pin mode
.. data:: Pin.STD
push-pull pin type
.. data:: Pin.STD_PU
push-pull pin with internall pull-up resistor
.. data:: Pin.STD_PD
push-pull pin with internall pull-down resistor
.. data:: Pin.OD
open-drain pin
.. data:: Pin.OD_PU
open-drain pin with pull-up resistor
.. data:: Pin.OD_PD
open-drain pin with pull-down resistor
.. data:: Pin.INT_FALLING
interrupt on falling edge
.. data:: Pin.INT_RISING
interrupt on rising edge
.. data:: Pin.INT_RISING_FALLING
interrupt on rising and falling edge
.. data:: Pin.INT_LOW_LEVEL
interrupt on low level
.. data:: Pin.INT_HIGH_LEVEL
interrupt on high level
.. data:: Pin.S2MA
2mA drive strength
.. data:: Pin.S4MA
4mA drive strength
.. data:: Pin.S6MA
6mA drive strength
.. only:: port_pyboard
class PinAF -- Pin Alternate Functions
======================================
A Pin represents a physical pin on the microcprocessor. Each pin
can have a variety of functions (GPIO, I2C SDA, etc). Each PinAF
object represents a particular function for a pin.
Usage Model::
x3 = pyb.Pin.board.X3
x3_af = x3.af_list()
x3_af will now contain an array of PinAF objects which are availble on
pin X3.
For the pyboard, x3_af would contain:
[Pin.AF1_TIM2, Pin.AF2_TIM5, Pin.AF3_TIM9, Pin.AF7_USART2]
Normally, each peripheral would configure the af automatically, but sometimes
the same function is available on multiple pins, and having more control
is desired.
To configure X3 to expose TIM2_CH3, you could use::
pin = pyb.Pin(pyb.Pin.board.X3, mode=pyb.Pin.AF_PP, af=pyb.Pin.AF1_TIM2)
or::
pin = pyb.Pin(pyb.Pin.board.X3, mode=pyb.Pin.AF_PP, af=1)
Methods
-------
.. method:: pinaf.__str__()
Return a string describing the alternate function.
.. method:: pinaf.index()
Return the alternate function index.
.. method:: pinaf.name()
Return the name of the alternate function.
.. method:: pinaf.reg()
Return the base register associated with the peripheral assigned to this
alternate function. For example, if the alternate function were TIM2_CH3
this would return stm.TIM2