Question

我正在树莓派3上编写python代码。我正在输入通道21上注册一个事件，以检查水分检测。我收到此错误运行时错误：无法添加边缘检测。我的代码是：

import RPi.GPIO as GPIO
import sys,os
import time
import datetime


channel = 21
led_output = 18
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(channel, GPIO.IN)
GPIO.setup(led_output, GPIO.OUT)


def callback(channel):
    filehandle = open("output.txt", "w") or die ("Could not write out")
    if GPIO.input(channel) == 1:
        print ("Water Detected!")
        filehandle.write("1")
        GPIO.output(led_output, GPIO.LOW)
    else:
        print ("Water Not Detected!")
        filehandle.write("0")
        GPIO.output(led_output, GPIO.HIGH)
    filehandle.close()




 GPIO.add_event_detect(channel, GPIO.BOTH, bouncetime=300)   
 GPIO.add_event_callback(channel, callback)  

    print(GPIO.input(channel))

    while True:
        time.sleep(5)

Answer 1

当我重新启动Raspberry并运行您的代码时，它运行完美。仅在终止进程或CTRL-C键盘中断并再次运行它之后，才会出现问题/错误。我认为这与以下事实有关：您没有正确清理就退出程序。如果您使用CTRL-C退出运行程序，并获得下面的代码，则在其中包含了 GPIO.cleanup（），但是...不幸的是，这并不能解决您只是杀死正在运行的程序的情况...在那种情况下，您仍然需要重新启动。因此，还有改进的空间。请再次重新插入您自己的文件管理命令。

import RPi.GPIO as GPIO  
import sys,os
import time
import datetime

channel = 21
led_output = 18
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.setup(channel, GPIO.IN)
GPIO.setup(led_output, GPIO.OUT)

def callback(channel):
    if GPIO.input(channel) == 1:
        print ("Water Detected!")
        GPIO.output(led_output, GPIO.LOW)
    else:
        print ("Water Not Detected!")
        GPIO.output(led_output, GPIO.HIGH)

GPIO.add_event_detect(channel, GPIO.BOTH, bouncetime=300)   
GPIO.add_event_callback(channel, callback)  
print(GPIO.input(channel))


try:
    while True:
        #main loop here with some (dummy) code
        eg_set_a_dummy_variable = 0

except KeyboardInterrupt:  
    # here you put any code you want to run before the program   
    # exits when you press CTRL+C  
    print ("Program interrupted by CTRL-C")

except:  
    # this catches ALL other exceptions including errors.  
    # You won't get any error messages for debugging  
    # so only use it once your code is working  
    print ("Other error or exception occurred!") 

finally:
     # this ensures a clean exit and prevents your
     # error "Runtime error:Failed to add edge detection"
     # in case you run your code for the second time after a break
    GPIO.cleanup()

     # credits to:
     # https://raspi.tv/2013/rpi-gpio-basics-3-how-to-exit-gpio-programs-cleanly-avoid-warnings-and-protect-your-pi

Answer 2

这不是一个很干净的解决方案，但是您也可以在脚本的开头调用GPIO.cleanup()，以防万一您的进程在之前被杀死而没有调用GPIO.cleanup()。

树莓派addEvent。运行时错误：无法添加边缘检测

2 个答案: