我正在开发一个在 Raspberrypi 上运行的 python 2.7 脚本。这个 Raspberry 是 v4 并且有一个 grovepi hat。按钮和 LCD 显示屏连接到这顶帽子。
所以我一直在使用 paho mqtt 库,但我不明白为什么我的回调(on_message 和 on_intrusion)没有被调用。这是我的代码:
import time
import LCDDisplay
import paho.mqtt.client as paho
import grovepi
import threading
broker_ip = '192.168.1.23'
broker_port = 1883
turn_on_topic = 'GreenHouse/Security/TurnOn'
intrusion_topic = 'GreenHouse/Security/IntrusionDetected'
message_topic = 'GreenHouse/Message'
message_display_duration = 5.0
button_port = 3
last_message = 'Initial display'
def display_last_message():
print('Timer starting')
LCDDisplay.setText(last_message)
LCDDisplay.setRGB(160,240,70)
message_timer = threading.Timer(message_display_duration, display_last_message)
def on_message(client, userdata, msg):
print('Message received')
LCDDisplay.setText('Message received')
LCDDisplay.setRGB(60,190,250)
if message_timer.is_alive():
message_timer.cancel()
message_timer = threading.Timer(message_display_duration, display_last_message)
message_timer.start()
def on_intrusion(client, userdata, msg):
LCDDisplay.setText('ALERT - INTRUSION DETECTED')
LCDDisplay.setRGB(240,65,65)
if __name__=="__main__":
display_last_message()
print('Connecting to broker...')
mqttClient = paho.Client('Button_LCD_Main')
mqttClient.message_callback_add(message_topic, on_message)
mqttClient.message_callback_add(intrusion_topic, on_intrusion)
mqttClient.connect(broker_ip, broker_port, 60)
print('Starting loop and button check')
mqttClient.loop_start()
grovepi.pinMode(button_port,"INPUT")
time.sleep(2) # Wait for button to initialize
try:
while True:
button_output = grovepi.digitalRead(button_port)
if button_output == 1:
print('Button activated')
mqttClient.publish(turn_on_topic)
time.sleep(1)
else:
time.sleep(0.2)
finally:
mqttClient.loop_stop()
mqttClient.disconnect()
我检查了 Raspberry 可以使用 'sudo mosquitto_sub -h
Timer starting
Connecting to broker...
Starting loop and button check
但最奇怪的是“发布”有效(我也检查了它,但在节点中使用带有 mqtt 的节点红色服务器)。 我还仔细检查了主题网址。
我很困惑,你能帮我吗?
调用
mqttClient.message_callback_add(topic, handler)
实际上并不订阅该主题,它只是为该主题设置一个特定的处理程序。
您仍然必须致电
mqttClient.subscribe(topic)
才能让经纪人向您发送匹配的消息。
最好的解决方案是添加一个
on_connect
回调来处理订阅
...
def on_connect(client, userdata, flags, rc):
client.subscribe(intrusion_topic)
client.subscribe(message_topic)
...
if __name__=="__main__":
display_last_message()
print('Connecting to broker...')
mqttClient = paho.Client('Button_LCD_Main')
mqttClient.message_callback_add(message_topic, on_message)
mqttClient.message_callback_add(intrusion_topic, on_intrusion)
mqttClient.on_connect = on_connect
mqttClient.connect(broker_ip, broker_port, 60)
...