A pin is the basic object to control I/O pins (also known as GPIO - general-purpose input/output). 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.
from machine import Pin
# initialize `P9` in gpio mode and make it an output
p_out = Pin('P9', mode=Pin.OUT)
p_out.value(1)
p_out.value(0)
p_out.toggle()
p_out(True)
# make `P10` an input with the pull-up enabled
p_in = Pin('P10', mode=Pin.IN, pull=Pin.PULL_UP)
p_in() # get value, 0 or 1
Create a new Pin object associated with the string id
. If additional arguments are given, they are used to initialise the pin. See pin.init()
from machine import Pin
p = Pin('P10', mode=Pin.OUT, pull=None, alt=-1)
Initialise the pin:
mode
can be one of:
Pin.IN
- input pin.Pin.OUT
- output pin in push-pull mode.Pin.OPEN_DRAIN
- input or output pin in open-drain mode.pull
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.*
0
or 1
alt
is the id of the alternate function.Returns: None
.
Get the pin id.
Get or set the digital logic level of the pin. This only works in Pin.OUT
mode. Values can be:
True
or 1: HighFalse
or 0: LowPin objects are callable. The call method provides a (fast) shortcut to set and get the value of the pin.
Example:
from machine import Pin
pin = Pin('P12', mode=Pin.IN, pull=Pin.PULL_UP)
pin() # fast method to get the value
See pin.value()
for more details.
Toggle the value of the pin.
Get or set the pin mode. Modes can be:
Pin.IN
Pin.OUT
Pin.OPEN_DRAIN
Get or set the pin pull. Pull can be:
Pin.PULL_UP
Pin.PULL_DOWN
None
Get or set the pin hold. This functionality can be used to hold a pin’s state after deepsleep, machine.reset()
or a watchdog timer reset. Passing True
will hold the current value of the pin, False
will release the hold state. When a pin is in hold state, its value cannot be changed by using Pin.value()
or Pin.toggle()
, until the hold is released. Only pins in the RTC power domain can retain their value through deep sleep or reset. These are: P2, P3, P4, P6, P8, P9, P10, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, P23
You can use the following example:
from machine import Pin
import machine
p3 = Pin('P3', mode=Pin.OUT)
p3.value(1) #can also be p3.value(0)
p3.hold(True) #hold the pin high
machine.reset()
# instead, you can use:
# machine.deepsleep(10000)
# P3 will still be high here
A few things to keep in mind when using the pin hold functionality:
machine.reset()
pin.hold()
will return False
after such reset, even though the pin is actually still held in hardware.pin.hold()
does not return the pin’s value. You can hold a pin high or low.Set a callback to be triggered when the input level at the pin changes.
trigger
is the type of event that triggers the callback. 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.The values can be OR-ed together, for instance trigger=Pin.IRQ_FALLING | Pin.IRQ_RISING
handler
is the function to be called when the event happens. This function will receive one argument. Set handler
to None
to disable it.arg
is an optional argument to pass to the callback. If left empty or set to None
, the function will receive the Pin object that triggered it.Example:
from machine import Pin
def pin_handler(arg):
print("got an interrupt in pin %s" % (arg.id()))
p_in = Pin('P10', mode=Pin.IN, pull=Pin.PULL_UP)
p_in.callback(Pin.IRQ_FALLING | Pin.IRQ_RISING, pin_handler)
For more information on how Pycom’s products handle interrupts, see here.
Contains all Pin objects supported by the expansion board. Examples:
Pin.exp_board.G16
led = Pin(Pin.exp_board.G16, mode=Pin.OUT)
Pin.exp_board.G16.id()
Contains all Pin
objects supported by the module. Examples:
Pin.module.P9
led = Pin(Pin.module.P9, mode=Pin.OUT)
Pin.module.P9.id()
The following constants are used to configure the pin objects. Note that not all constants are available on all ports.
Pin.IN
, Pin.OUT
, Pin.OPEN_DRAIN
Pin.PULL_UP
, Pin.PULL_DOWN