Question

我想知道是否可以让我的瞬间按钮控制Python中的继电器而我按住按钮是什么时候？

实质上，当按下按钮时，继电器开启，当按钮松开时，继电器关闭。

目前，我可以使用一个小的python脚本控制继电器，将其打开持续5个秒：

relay.py：

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
GPIO.setup(4, GPIO.OUT)

GPIO.output(4, GPIO.LOW)
time.sleep(5)
GPIO.output(4, GPIO.HIGH)
GPIO.cleanup()

print "Done!"

能够跟踪瞬间按钮何时被按下：

button.py：

import os
from time import sleep
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setup(25, GPIO.IN)

while True:
        if (GPIO.input(25) == False):
                print "Button being pushed!"
        GPIO.output(4, GPIO.LOW)
        sleep(0.025)

我试图将这两者结合在一起：

import os
from time import sleep
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setup(25, GPIO.IN)
GPIO.setup(4, GPIO.OUT)

while True:
        if (GPIO.input(25) == False):
                print "Button being pushed!"
                GPIO.output(4, GPIO.LOW)
        sleep(0.025)
        GPIO.output(4, GPIO.HIGH)

但无济于事。任何帮助都会非常感激！

Answer 1

当然，这应该可以解决问题。我没有测试它，所以可能需要一些小的编辑。

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

# Added a software pull-up here for increased stability
GPIO.setup(25, GPIO.IN, GPIO.PUD_UP)
GPIO.setup(4, GPIO.OUT)
# The relay seems to be active low. Default to off.
GPIO.output(4, GPIO.HIGH)

# This function is run every time the button state changes 
# from low to high or high to low (GPIO.BOTH)
def callback_func(pin):
    # The button transitioned to high (released) 
    if GPIO.input(pin):
        # Relay off
        GPIO.output(4, GPIO.HIGH)
    else:
        # The button went low (it was pressed). Relay on.
        GPIO.output(4, GPIO.LOW)

# Set up threaded event detection (no constant polling of pin states).
# Fires on both high-to-low and low-to-high state changes.
GPIO.add_event_detect(25, GPIO.BOTH, callback=callback_func)

def main():
    while True:
        print "Not blocking! You're free to do other stuff here"
        time.sleep(5)

if __name__ == "__main__":
    main()

如果释放按钮时GPIO.PUD_UP没有引起上升沿，则必须在VCC上添加一个电阻。无论如何这样做是个好主意，因为即使软件失败，它也能确保继电器保持默认状态。

一个丑陋的版本，当按下按钮时不断写入继电器GPIO，但应该没有上拉：

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(25, GPIO.IN, GPIO.PUD_UP)
GPIO.setup(4, GPIO.OUT)
GPIO.output(4, GPIO.HIGH)

def callback_func(pin):
    while not GPIO.input(pin):
        GPIO.output(4, GPIO.LOW)
    GPIO.output(4, GPIO.HIGH)

GPIO.add_event_detect(25, GPIO.FALLING, callback=callback_func, bouncetime=100)

def main():
    while True:
        print "Not blocking! You're free to do other stuff here"
        time.sleep(5)

if __name__ == "__main__":
    main()

GPIO瞬时按钮控制继电器

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