20170904 （第3课）树莓派PYPI- 呼吸灯

任何常规LED都可以使用PWM（脉冲宽度调制）设置其亮度值。在GPIO Zero中，可以PWMLED使用0和1之间的值来实现：

#LEDPWM1.PY
from gpiozero import PWMLED
from time import sleep

led = PWMLED(17)

while True:
led.value = 0 # off
sleep(1)
led.value = 0.5 # half brightness
sleep(1)
led.value = 1 # full brightness
sleep(1)

#LEDPWM1.PY

from gpiozero import PWMLED

from time import sleep

led = PWMLED(17)

while True:

led.value = 0 # off

sleep(1)

led.value = 0.5 # half brightness

sleep(1)

led.value = 1 # full brightness

sleep(1)

[cc lang="python"]
#LEDPWM2.PY
from gpiozero import PWMLED
from time import sleep

led = PWMLED(17)

while True:
for num in range(0,100):
led.value=num/100
sleep(0.1)
for num in range(0,10):
led.value=(10-num)/10
sleep(0.1)
[/cc]

[cc lang="python"]

#LEDPWM2.PY

from gpiozero import PWMLED

from time import sleep

led = PWMLED(17)

while True:

for num in range(0,100):

led.value=num/100

sleep(0.1)

for num in range(0,10):

led.value=(10-num)/10

sleep(0.1)

[/cc]

[cc lang="python"]
#LEDPWM3.PY
from gpiozero import PWMLED
from signal import pause

led = PWMLED(17)

led.pulse(fade_in_time=3, fade_out_time=1)

pause()

[cc lang="python"]

#LEDPWM3.PY

from gpiozero import PWMLED

from signal import pause

led = PWMLED(17)

led.pulse(fade_in_time=3, fade_out_time=1)

pause()

[/cc]

[cc lang="python"]
#LEDPWM4.PY
from gpiozero import PWMLED,Button
from signal import pause

led = PWMLED(17)

button = Button(2)

while True:
button.wait_for_press()
led.pulse()
button.wait_for_release()
led.off()
pause()
[/cc]

[cc lang="python"]

#LEDPWM4.PY

from gpiozero import PWMLED,Button

from signal import pause

led = PWMLED(17)

button = Button(2)

while True:

button.wait_for_press()

led.pulse()

button.wait_for_release()

led.off()

pause()

[/cc]

[cc lang="python"]
#LEDPWM5.PY
from gpiozero import PWMLED,Button
from signal import pause

led = PWMLED(17)

button = Button(2)

button.when_pressed = led.pulse
button.when_released = led.off

pause()
[/cc]