试图通过MQTT发送一条消息，并睡眠5秒。

Question

我目前正试图通过MQTT协议发送一条消息，这条消息是有效的。我使用一个树莓派和一个振动传感器作为触发消息发送的手段。在开始的时候，我会触摸传感器，它将一次发送大量的消息，这是我不希望发生的。但现在它检测到一个振动，然后不会检测到另一个振动，但不会停止文件的运行，我可以让它再次检测振动的唯一方法是再次运行文件。

import time
from grove.gpio import GPIO

import paho.mqtt.client as mqttClient


class GrovePiezoVibrationSensor(GPIO):
    def __init__(self, pin):
        super(GrovePiezoVibrationSensor, self).__init__(pin, GPIO.IN)
        self._on_detect = None

    @property
    def on_detect(self):
        return self._on_detect

    @on_detect.setter
    def on_detect(self, callback):
        if not callable(callback):
            return

        if self.on_event is None:
            self.on_event = self._handle_event

        self._on_detect = callback

    def _handle_event(self, pin, value):
        if value:
            if callable(self._on_detect):
                self._on_detect()
                time.sleep(5000)


Grove = GrovePiezoVibrationSensor
def on_connect(client, userdata, flags, rc):

    if rc == 0:

        print("Connected to broker")

        global Connected                #Use global variable
        Connected = True                #Signal connection

    else:

        print("Connection failed")

Connected = False   #global variable for the state of the connection

broker_address= "hairdresser.cloudmqtt.com"
port = 15767
user = "kprpjfue"
password = "1fIq2_CIwHZj"
client = mqttClient.Client("Python")               #create new instance
client.username_pw_set(user, password=password)    #set username and password
client.on_connect= on_connect
client.loop_start()

client.connect(broker_address, port=port)



def main():
    from grove.helper import SlotHelper
    sh = SlotHelper(SlotHelper.GPIO)
    pin = sh.argv2pin()

    pir = GrovePiezoVibrationSensor(pin)

    def callback():
        print('Detected.')
        value = 'detected'
        client.publish("sensor/Temp", value)

    pir.on_detect = callback
    while True:
        time.sleep(5000)

if __name__ == '__main__':
    main()


while Connected != True:    #Wait for connection
    time.sleep(0.1)

import time
from grove.gpio import GPIO

import paho.mqtt.client as mqttClient


class GrovePiezoVibrationSensor(GPIO):
    def __init__(self, pin):
        super(GrovePiezoVibrationSensor, self).__init__(pin, GPIO.IN)
        self._on_detect = None

    @property
    def on_detect(self):
        return self._on_detect

    @on_detect.setter
    def on_detect(self, callback):
        if not callable(callback):
            return

        if self.on_event is None:
            self.on_event = self._handle_event

        self._on_detect = callback

    def _handle_event(self, pin, value):
        if value:
            if callable(self._on_detect):
                self._on_detect()
                time.sleep(5000)


Grove = GrovePiezoVibrationSensor
def on_connect(client, userdata, flags, rc):

    if rc == 0:

        print("Connected to broker")

        global Connected                #Use global variable
        Connected = True                #Signal connection

    else:

        print("Connection failed")

Connected = False   #global variable for the state of the connection

broker_address= "hairdresser.cloudmqtt.com"
port = 15767
user = "kprpjfue"
password = "1fIq2_CIwHZj"
client = mqttClient.Client("Python")               #create new instance
client.username_pw_set(user, password=password)    #set username and password
client.on_connect= on_connect

client.connect(broker_address, port=port)



def main():
    from grove.helper import SlotHelper
    sh = SlotHelper(SlotHelper.GPIO)
    pin = sh.argv2pin()

    pir = GrovePiezoVibrationSensor(pin)

    def callback():
        print('Detected.')
        value = 'detected'
        client.publish("sensor/Temp", value)

    pir.on_detect = callback
    while True:
        time.sleep(5000)
        client.loop()

if __name__ == '__main__':
    main()


while Connected != True:    #Wait for connection
    time.sleep(0.1)

如你所见，在处理事件方法的if callable下，我告诉我说time.sleep(5000). 我是不是把这个放在了错误的地方？

Answer 1

你还没有开始MQTT客户端网络循环，所以它将无法接收消息或发送大的MTU的消息。

你也会在保持生命期后被断开连接。

添加 client.loop_start() 临行前 client.connect()

或插入 client.loop() 之后 time.sleep(5000) 在main的循环中，最好让它变成1000，让客户端循环至少每秒运行一次。

在回调中添加睡眠通常是个坏主意，因为它不会阻止事件被触发，只是会延迟它们，因为它们会一直排队直到睡眠时间结束。

你应该在发送MQTT消息后的第一个事件上设置一个标志，然后你可以使用main中的While True循环使其失效。如果一个新的事件进来的时候标志还在设置，那么你就不要再发送MQTT消息了。