mirror of
https://github.com/sascha-hemi/pycom-documentation.git
synced 2026-03-21 08:06:34 +01:00
154 lines
4.5 KiB
Markdown
154 lines
4.5 KiB
Markdown
# Pin
|
||
|
||
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.
|
||
|
||
## Quick Usage Example
|
||
|
||
```python
|
||
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
|
||
```
|
||
|
||
## Constructors
|
||
|
||
#### class machine.Pin\(id, ...\)
|
||
|
||
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\(\)](pin.md#pin-init-mode-pull-alt)
|
||
|
||
```python
|
||
from machine import Pin
|
||
p = Pin('P10', mode=Pin.OUT, pull=None, alt=-1)
|
||
```
|
||
|
||
## Methods
|
||
|
||
#### pin.init\(mode, pull, \* , alt\)
|
||
|
||
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.
|
||
* `alt` is the id of the alternate function.
|
||
|
||
Returns: `None`.
|
||
|
||
#### pin.id\(\)
|
||
|
||
Get the pin id.
|
||
|
||
#### 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\(\[value\]\)
|
||
|
||
Pin objects are callable. The call method provides a \(fast\) shortcut to set and get the value of the pin.
|
||
|
||
Example:
|
||
|
||
```python
|
||
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.
|
||
|
||
#### pin.toggle\(\)
|
||
|
||
Toggle the value of the pin.
|
||
|
||
#### pin.mode\(\[mode\]\)
|
||
|
||
Get or set the pin mode.
|
||
|
||
#### pin.pull\(\[pull\]\)
|
||
|
||
Get or set the pin pull.
|
||
|
||
#### pin.hold\(\[hold\]\)
|
||
|
||
Get or set the pin hold. You can apply a hold to a pin by passing `True` \(or clear it by passing `False`\). When a pin is held, its value cannot be changed by using `Pin.value()` or `Pin.toggle()` until the hold is released. This Can be used to retain the pin state through a core reset and system reset triggered by watchdog time-out or Deep-sleep events. 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`
|
||
|
||
#### pin.callback\(trigger, handler=None, arg=None\)
|
||
|
||
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:
|
||
|
||
```python
|
||
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)
|
||
```
|
||
|
||
{% hint style="info" %}
|
||
For more information on how Pycom’s products handle interrupts, see [here](../../notes.md#interrupt-handling).
|
||
{% endhint %}
|
||
|
||
## Attributes
|
||
|
||
#### class pin.exp\_board
|
||
|
||
Contains all Pin objects supported by the expansion board. Examples:
|
||
|
||
```python
|
||
Pin.exp_board.G16
|
||
led = Pin(Pin.exp_board.G16, mode=Pin.OUT)
|
||
Pin.exp_board.G16.id()
|
||
```
|
||
|
||
#### class pin.module
|
||
|
||
Contains all `Pin` objects supported by the module. Examples:
|
||
|
||
```python
|
||
Pin.module.P9
|
||
led = Pin(Pin.module.P9, mode=Pin.OUT)
|
||
Pin.module.P9.id()
|
||
```
|
||
|
||
## Constants
|
||
|
||
The following constants are used to configure the pin objects. Note that not all constants are available on all ports.
|
||
|
||
* Selects the pin mode: `Pin.IN`, `Pin.OUT`, `Pin.OPEN_DRAIN`
|
||
* Enables the pull up or pull down resistor: `Pin.PULL_UP`, `Pin.PULL_DOWN`
|
||
|