class PinAF – pin alternate functions#

Each STM32 pin can serve as plain GPIO or as one of several peripheral alternate functions (UART4_TX, I2C2_SCL, TIM2_CH3, etc.). A PinAF object describes a single alternate function that is wired to a particular pin, and is what Pin.af_list() returns.

Usage Model:

p4 = pyb.Pin.board.P4
p4_af = p4.af_list()

p4_af now holds the list of PinAF objects available on P4. The exact list depends on the STM32 MCU on the OpenMV Cam in use.

Normally each peripheral driver configures the alternate function it needs automatically. When the same peripheral function is wired to more than one pin, or several functions share a pin, you can pick one explicitly through Pin.ALT either by name:

pin = pyb.Pin(pyb.Pin.board.P4, mode=pyb.Pin.ALT, alt=pyb.Pin.AF1_TIM2)

or by raw index:

pin = pyb.Pin(pyb.Pin.board.P4, mode=pyb.Pin.ALT, alt=1)

Constructors#

class pyb.PinAF#

PinAF objects are not constructed directly. Use Pin.af_list() to enumerate the alternate functions available on a given pin.

Methods#

__str__() → str#: Return a string describing the alternate function (its name and index).

index() → int#: Return the alternate-function index. The same integer is accepted by the alt argument of Pin.init().

name() → str#: Return the name of the alternate function, for example "TIM2_CH3".

reg() → int#: Return the base register address of the peripheral assigned to this alternate function. For example, if the alternate function were TIM2_CH3 this would return stm.TIM2.