Esp32笔记（4）MQTT通信入门之循环发送消息

Esp32笔记（4）MQTT通信

编写代码完成esp32上的mqtt客户端，
每隔1秒钟发布如下消息：
消息主题：“id”
消息内容：“你的学号”

1.代码

#Hardware Platform: FireBeetle-ESP32
#Result: input MQTTlibrary and remote controls LED by mqtt communication.

from umqtt.simple import MQTTClient
from machine import Pin
import network
import time

SSID="xlu"
PASSWORD="111222333"

led=Pin(2, Pin.OUT, value=0)

SERVER = "你的mqtt服务器ip
CLIENT_ID = "你的id" # 如果有两个id一样的,可能会发生一些意想不到的申请 
TOPIC = b"你的主题" # 主题主题主题
username='你的mqtt服务器账号'
password='你的mqtt服务器密码'
state = 0
c=None
def sub_cb(topic, msg):
  global state
  print((topic, msg))
  if msg == b"on":
    led.value(1)
    state = 0
    print("1")
  elif msg == b"off":
    led.value(0)
    state = 1
    print("0")
  elif msg == b"toggle":
    # LED is inversed, so setting it to current state
    # value will make it toggle
    led.value(state)
    state = 1 - state
def connectWifi(ssid,passwd):
  global wlan
  wlan=network.WLAN(network.STA_IF)         #create a wlan object
  wlan.active(True)                         #Activate the network interface
  wlan.disconnect()                         #Disconnect the last connected WiFi
  wlan.connect(ssid,passwd)                 #connect wifi
  while(wlan.ifconfig()[0]=='0.0.0.0'):
    time.sleep(1)
  
    
#Catch exceptions,stop program if interrupted accidentally in the 'try'
try:
  connectWifi(SSID,PASSWORD)
  server=SERVER
  c = MQTTClient(CLIENT_ID, server,0,username,password)     #create a mqtt client
  c.set_callback(sub_cb)                    #set callback
  c.connect()                               #connect mqtt
  c.subscribe(TOPIC)                        #client subscribes to a topic
  print("Connected to %s, subscribed to %s topic" % (server, TOPIC))

  while True:
    c.publish(TOPIC, '发送的消息') # 循环发送消息
    time.sleep(1)# 休息一秒
finally:
  if(c is not None):
    c.disconnect()
  wlan.disconnect()
  wlan.active(False)

设置回调函数

  c.set_callback(sub_cb)                    #set callback

配置服务器参数

SERVER = "你的mqtt服务器ip
CLIENT_ID = "你的id" # 如果有两个id一样的,可能会发生一些意想不到的申请 
TOPIC = b"你的主题" # 主题主题主题
username='你的mqtt服务器账号'
password='你的mqtt服务器密码'

发送消息

  while True:
    c.publish(TOPIC, '发送的消息') # 循环发送消息
    time.sleep(1)# 休息一秒

结果,一秒一次