python - 如何在 Python 代码继续运行时连续闪烁 LED(或其他 while 循环)

Question

我希望能够在主 while 循环继续时让 LED 持续闪烁。我知道在下面的代码中，当函数 led_flash() 被调用时，脚本将停止，直到函数中定义的 while 循环结束。这会禁止其余代码运行。

import RPi.GPIO as GPIO
import time

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

def led_flash():
    while TRUE:
        GPIO.output(25, ON)
        time.sleep(1)
        GPIO.output(25, OFF)
        time.sleep(1)

while True:
    if x=1
        led_flash()
        ...do other stuff

我已经读到线程可以在这种情况下工作，但是我还没有找到足够简单的例子让我掌握。此外，如果线程化，我将如何在主 while 循环中结束 led_flash() 函数线程？

Answer 1

基于 here 的回答和 here你可以像这样开始一个线程:

import threading
while True:
    if x = 1:
        flashing_thread = threading.Thread(target=led_flash)
        flashing_thread.start()
        #continue doing stuff

因为在您的情况下，您想要停止线程(我假设如果 x 不等于 1)，那么您可以创建一个线程停止类，例如所以:

import threading
import sys

class StopThread(StopIteration): pass

threading.SystemExit = SystemExit, StopThread

class Thread2(threading.Thread):

    def stop(self):
        self.__stop = True

    def _bootstrap(self):
        if threading._trace_hook is not None:
            raise ValueError('Cannot run thread with tracing!')
        self.__stop = False
        sys.settrace(self.__trace)
        super()._bootstrap()

    def __trace(self, frame, event, arg):
        if self.__stop:
            raise StopThread()
        return self.__trace

并这样调用它:flashing_thread.stop()

把它们放在一起得到:

import threading
import sys
import RPi.GPIO as GPIO
import time

class StopThread(StopIteration): pass

threading.SystemExit = SystemExit, StopThread

class Thread2(threading.Thread):

    def stop(self):
        self.__stop = True

    def _bootstrap(self):
        if threading._trace_hook is not None:
            raise ValueError('Cannot run thread with tracing!')
        self.__stop = False
        sys.settrace(self.__trace)
        super()._bootstrap()

    def __trace(self, frame, event, arg):
        if self.__stop:
            raise StopThread()
        return self.__trace
#############################################################

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

def led_flash():
    while TRUE:
        GPIO.output(25, ON)
        time.sleep(1)
        GPIO.output(25, OFF)
        time.sleep(1)

# x gets defined somewhere

while True:
    if x == 1:
        flashing_thread = Thread2(target=led_flash)
        flashing_thread.start()
        #continue doing stuff
    else:
        if flashing_thread and flashing_thread.isAlive():
            flashing_thread.stop()