mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-10-29 17:50:37 +00:00
b1913e5e39
Fairly major tidy up of the hierarchy as well. There's now a trivial base class: InputDevice which simply permits reading of state. WaitableInputDevice descends from this and introduces waitable events and callbacks, and provides a hook for calling them but needs further machinery to activate that hook. DigitalInputDevice (crap name?) descends from WaitableInputDevice and uses the standard RPi.GPIO callback mechanisms to handle events. This is intended for use with trivial on/off devices with predictably small bounce times. Next is SmoothedInputDevice (crap name?) which also descends from WaitableInputDevice. This includes a background threaded queue which constantly monitors the state of the device and provides a running mean of its state. This is compared to a threshold for determining active / inactive state. This is intended for use with on/off devices that "jitter" a lot and for which a running average is therefore appropriate or for devices which provide an effectively analog readout (like charging capacitor timings). MonitorSensor and LightSensor now descend from SmoothedInputDevice, and Button descends from DigitalInputDevice. All "concrete" classes provide event aliases appropriate to their function (e.g. when_dark, when_pressed, etc.)
209 lines
3.2 KiB
Markdown
209 lines
3.2 KiB
Markdown
# gpio-zero
|
|
|
|
A simple interface to everyday GPIO components used with Raspberry Pi
|
|
|
|
## Why?
|
|
|
|
The "hello world" program in Java is at least 5 lines long, and contains 11
|
|
jargon words which are to be ignored. The "hello world" program in Python is
|
|
one simple line. However, the "hello world" of physical computing in Python
|
|
(flashing an LED) is similar to the Java program:
|
|
|
|
```python
|
|
import RPi.GPIO as GPIO
|
|
|
|
GPIO.setmode(GPIO.BCM)
|
|
GPIO.setwarnings(False)
|
|
|
|
red = 2
|
|
|
|
GPIO.setup(red, GPIO.OUT)
|
|
|
|
GPIO.output(red, True)
|
|
```
|
|
|
|
6 lines of code to flash an LED. And skipping over why `GPIO` is used twice in
|
|
the first line; what `BCM` means; why set warnings to False; and so on. Young
|
|
children and beginners shouldn't need to sit and copy out several lines of text
|
|
they're told to ignore. They should be able to read their code and understand
|
|
what it means. This module provides a simple interface to everyday components.
|
|
The LED example becomes:
|
|
|
|
```python
|
|
from gpiozero import LED
|
|
|
|
red = LED(2)
|
|
|
|
red.on()
|
|
```
|
|
|
|
Any guesses how to turn it off?
|
|
|
|
## Implemented Components
|
|
|
|
- LED
|
|
- Buzzer
|
|
- Button
|
|
- Motion Sensor
|
|
- Light Sensor
|
|
- Temperature Sensor
|
|
- Motor
|
|
|
|
## Usage
|
|
|
|
### LED
|
|
|
|
Turn an LED on and off repeatedly:
|
|
|
|
```python
|
|
from gpiozero import LED
|
|
from time import sleep
|
|
|
|
red = LED(2)
|
|
|
|
while True:
|
|
red.on()
|
|
sleep(1)
|
|
red.off()
|
|
sleep(1)
|
|
```
|
|
|
|
Alternatively:
|
|
|
|
```python
|
|
from gpiozero import LED
|
|
|
|
red = LED(2)
|
|
red.blink(1, 1)
|
|
sleep(10)
|
|
```
|
|
|
|
### Buzzer
|
|
|
|
Turn a buzzer on and off repeatedly:
|
|
|
|
```python
|
|
from gpiozero import Buzzer
|
|
from time import sleep
|
|
|
|
buzzer = Buzzer(3)
|
|
|
|
while True:
|
|
buzzer.on()
|
|
sleep(1)
|
|
buzzer.off()
|
|
sleep(1)
|
|
```
|
|
|
|
### Button
|
|
|
|
Check if a button is pressed:
|
|
|
|
```python
|
|
from gpiozero import Button
|
|
|
|
button = Button(4)
|
|
|
|
if button.is_active:
|
|
print("Button is pressed")
|
|
else:
|
|
print("Button is not pressed")
|
|
```
|
|
|
|
Wait for a button to be pressed before continuing:
|
|
|
|
```python
|
|
from gpiozero import Button
|
|
|
|
button = Button(4)
|
|
|
|
button.wait_for_press()
|
|
print("Button was pressed")
|
|
```
|
|
|
|
Run a function every time the button is pressed:
|
|
|
|
```python
|
|
from gpiozero import Button
|
|
|
|
def warning():
|
|
print("Don't push the button!")
|
|
|
|
button = Button(4)
|
|
|
|
button.when_pressed = warning
|
|
```
|
|
|
|
### Motion Sensor
|
|
|
|
Detect motion and light an LED when it's detected:
|
|
|
|
```python
|
|
from gpiozero import MotionSensor, LED
|
|
|
|
pir = MotionSensor(5)
|
|
led = LED(16)
|
|
|
|
pir.when_motion = led.on
|
|
pir.when_no_motion = led.off
|
|
```
|
|
|
|
### Light Sensor
|
|
|
|
Wait for light and dark:
|
|
|
|
```python
|
|
from gpiozero import LightSensor
|
|
|
|
sensor = LightSensor(18)
|
|
|
|
while True:
|
|
sensor.wait_for_light()
|
|
print("It's light! :)")
|
|
sensor.wait_for_dark()
|
|
print("It's dark :(")
|
|
```
|
|
|
|
Run a function when the light changes:
|
|
|
|
```python
|
|
from gpiozero import LightSensor, LED
|
|
|
|
sensor = LightSensor(18)
|
|
led = LED(16)
|
|
|
|
sensor.when_dark = led.on
|
|
sensor.when_light = led.off
|
|
```
|
|
|
|
### Temperature Sensor
|
|
|
|
Retrieve light sensor value:
|
|
|
|
```python
|
|
from gpiozero import TemperatureSensor
|
|
|
|
temperature = TemperatureSensor(6)
|
|
|
|
print(temperature.value)
|
|
```
|
|
|
|
### Motor
|
|
|
|
Drive two motors forwards for 5 seconds:
|
|
|
|
```python
|
|
from gpiozero import Motor
|
|
from time import sleep
|
|
|
|
left_motor = Motor(7)
|
|
right_motor = Motor(8)
|
|
|
|
left_motor.on()
|
|
right_motor.on()
|
|
sleep(5)
|
|
left_motor.off()
|
|
right_motor.off()
|
|
```
|
|
|