クラス Pin -- I/O ピンの制御¶
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:
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.Pin.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.A0
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:
- Directly specify a pin object
- User supplied mapping function
- User supplied mapping (object must be usable as a dictionary key)
- Supply a string which matches a board pin
- 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).
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.
コンストラクタ¶
-
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
pin.init()
.
Class methods¶
-
classmethod
Pin.
debug
([state])¶ Get or set the debugging state (
True
orFalse
for on or off).
-
classmethod
Pin.
dict
([dict])¶ Get or set the pin mapper dictionary.
-
classmethod
Pin.
mapper
([fun])¶ Get or set the pin mapper function.
メソッド¶
-
Pin.
init
(mode, pull=Pin.PULL_NONE, *, value=None, alt=-1)¶ Initialise the pin:
mode は以下のいずれかです:
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.
value if not None will set the port output value before enabling the pin.
alt can be used when mode is
Pin.AF_PP
orPin.AF_OD
to set the index or name of one of the alternate functions associated with a pin. This arg was previously called af which can still be used if needed.
Returns:
None
.
-
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 toTrue
, the pin is set high, otherwise it is set low.
-
Pin.
__str__
()¶ Return a string describing the pin object.
-
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.
-
Pin.
af_list
()¶ Returns an array of alternate functions available for this pin.
-
Pin.
gpio
()¶ Returns the base address of the GPIO block associated with this pin.
-
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.
-
Pin.
name
()¶ Get the pin name.
-
Pin.
names
()¶ Returns the cpu and board names for this pin.
-
Pin.
pin
()¶ Get the pin number.
-
Pin.
port
()¶ Get the pin port.
-
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.
定数¶
-
Pin.
AF_OD
¶ initialise the pin to alternate-function mode with an open-drain drive
-
Pin.
AF_PP
¶ initialise the pin to alternate-function mode with a push-pull drive
-
Pin.
ANALOG
¶ initialise the pin to analog mode
-
Pin.
IN
¶ initialise the pin to input mode
-
Pin.
OUT_OD
¶ initialise the pin to output mode with an open-drain drive
-
Pin.
OUT_PP
¶ initialise the pin to output mode with a push-pull drive
-
Pin.
PULL_DOWN
¶ enable the pull-down resistor on the pin
-
Pin.
PULL_NONE
¶ don't enable any pull up or down resistors on the pin
-
Pin.
PULL_UP
¶ enable the pull-up resistor on the pin
class PinAF -- Pin Alternate Functions¶
A Pin represents a physical pin on the microprocessor. Each pin can have a variety of functions (GPIO, I2C SDA, etc). Each PinAF object represents a particular function for a pin.
よくある使用例:
x3 = pyb.Pin.board.X3
x3_af = x3.af_list()
x3_af will now contain an array of PinAF objects which are available 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 alternate function 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, alt=pyb.Pin.AF1_TIM2)
or:
pin = pyb.Pin(pyb.Pin.board.X3, mode=pyb.Pin.AF_PP, alt=1)
メソッド¶
-
pinaf.
__str__
()¶ Return a string describing the alternate function.
-
pinaf.
index
()¶ Return the alternate function index.
-
pinaf.
name
()¶ Return the name of the alternate function.
-
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