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:

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.

构造函数 ¶

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 or False 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.

方法 ¶

Pin. init ( mode , pull=Pin.PULL_NONE , \* , value=None , alt=-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.

value if not None will set the port output value before enabling the pin.

alt can be used when mode is Pin.AF_PP or Pin.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.

返回： 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 to True , 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.

常量 ¶

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.

Usage Model:

										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 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)
										
									

或：

										pin = pyb.Pin(pyb.Pin.board.X3, mode=pyb.Pin.AF_PP, af=1)
										
									

方法 ¶

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