GPIO 瞬时按钮控制继电器

Question

我想知道是否可以让我的瞬时按钮在按住按钮的同时控制 Python 中的继电器？

本质上，按下按钮时，继电器打开，松开按钮时，继电器关闭。

目前，我可以用一个小 python 脚本控制继电器，将其打开持续 5 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!"

并且能够在按下瞬时按钮时进行跟踪：

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)

我试图在这个时尚中将两者结合起来：

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。任何帮助将不胜感激！

Answer 1

当然，这应该可以解决问题。我没有对其进行测试，因此可能需要进行一些小的修改。

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

一个更丑陋的版本，在按下按钮时不断写入继电器 GPIO，但应该可以在没有上拉的情况下工作：

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

GPIO Momentary button controls relay

python

raspberry-pi

gpio