Freenove Ultimate Starter Kit, Руководство пользователя

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Chapter 2 Button & LED
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loop ( )
e x cept KeyboardInterrupt : # When 'Ctrl+C' is pressed, the subprogram destroy() will
be executed.
destroy ()
RPi.GPIO provides us with a simple and effective function to eliminate the jitter, that is
GPIO.add_event_detect(). It uses callback function. Once it detect that the buttonPin has a specified action
FALLING, execute the specified function buttonEvent(). In the function buttonEvent, each time the ledState is
reversed, the state of the LED will be updated.
d e f buttonEvent ( channel ):
g l obal ledState
p r int 'buttonEvent GPIO%d' % channel
ledState = n o t ledState
i f ledState :
p r int ( 'Turn on LED ... ' )
e l se :
p r int ( 'Turn off LED ... ' )
GPIO . output ( ledPin , ledState )
d e f loop ( ):
#Button detect
GPIO . add_event_detect ( buttonPin , GPIO . FALLING , callback = buttonEvent , bouncetime = 300 )
w h ile T r ue :
p a ss
Of course, you can also use the same programming idea of C code above to achieve this target.
GPIO.add_event_detect(channel, GPIO.RISING, callback=my_callback, bouncetime=200)
This is an event detection function. The first parameter specifies the IO port to be detected. The second
parameter specifies the action to be detected. The third parameter specified a function name, the function
will be executed when the specified action is detected. And the fourth parameter is used to set the jitter
time.