NodeMCU--MQTT学习笔记（一）

官方文档：https://nodemcu.readthedocs.io/en/master/en/modules/mqtt/

mqtt.Client()

语法：

mqtt.Client(clientid, keepalive[, username, password, cleansession])

参数：

• clientid client ID
• keepalive keepalive seconds
• username user name
• password user password
• cleansession 0/1 for false/true. Default is 1 (true).

mqtt.client:connect()

语法：

mqtt:connect(host[, port[, secure[, autoreconnect]]][, function(client)[, function(client, reason)]])

参数：

• host ：主机、域名或者是IP地址（字符串）
• port ：MQTT服务器的端口号（数字），默认1883
• secure 0/1 for false/true, default 0. Take note of constraints documented in the net module.
• autoreconnect 0/1 for false/true, default 0. This option is deprecated.
• function(client) callback function for when the connection was established
• function(client, reason) callback function for when the connection could not be established. No further callbacks should be called.

mqtt.client:on()

语法：

mqtt:on(event, function(client[, topic[, message]]))

参数：

• event ：注册的事件可以是”connect”、”message” 或者是”offline”
• function(client[, topic[, message]])：回调函数。 第一个参数是客户端，如果注册的事件是“message”,那么第二个和第三个参数是得到的主题和消息（字符串）

首先一个简单的例子：

client = mqtt.Client("NodeMCU_Client", 120)

function handle_mqtt_error(client, reason) -- 定义mqtt错误处理函数
  print("fail reason" .. reason) 
end

function do_mqtt_connect(client)   -- 定义连接上mqtt处理函数
  print("connected")
  client:publish("nodemcu", "Hello World", 0, 0)
end

client:connect("www.liefyuan.top", do_mqtt_connect, handle_mqtt_error)

在这个基础上添加一个定时器，每10秒发送一个消息

client = mqtt.Client("NodeMCU_Client", 120)

function handle_mqtt_error(client, reason) -- 定义mqtt错误处理函数
  print("fail reason" .. reason) 
end

function do_mqtt_connect(client)   -- 定义连接上mqtt处理函数
  print("connected")
  client:publish("nodemcu", "Hello World", 0, 0)
end

client:connect("www.liefyuan.top", do_mqtt_connect, handle_mqtt_error)

function do_timer()  -- 定义定时器处理函数
  print("connected")
  client:publish("nodemcu", "hoho", 0, 0) 
end 

tmr.alarm(1, 10000, tmr.ALARM_AUTO, do_timer)

在上面的基础上增加一个subscribe功能：

client = mqtt.Client("NodeMCU_Client", 120)

function handle_mqtt_error(client, reason) -- 定义mqtt错误处理函数
  print("fail reason" .. reason) 
end

function do_mqtt_connect(client)   -- 定义连接上mqtt处理函数
  print("connected")
  client:publish("nodemcu", "Hello World", 0, 0)  -- 推送一条消息
  client:subscribe("led", 0, function(client) print("subscribe success") end)  -- 订阅一个主题
end

client:connect("www.liefyuan.top", do_mqtt_connect, handle_mqtt_error)

function do_mqtt_message(client, topic, data)  -- 定义一个订阅消息接收处理函数
    print(topic .. ": ")
    if data ~= nil then
        print(data)
    end
end

client:on("message", do_mqtt_message)

function do_timer()  -- 定义定时器处理函数
  print("connected")
  client:publish("nodemcu", "hoho", 0, 0) 
end 

tmr.alarm(1, 10000, tmr.ALARM_AUTO, do_timer)

增加：判断接收的数据，如果是1，则打开LED灯，否则熄灭LED灯

pin=0 -- 0就是D0
gpio.mode(pin, gpio.OUTPUT)

client = mqtt.Client("NodeMCU_Client", 120)

-------------------------------------------------

function handle_mqtt_error(client, reason) -- 定义mqtt错误处理函数
  print("fail reason" .. reason) 
end

function do_mqtt_connect(client)   -- 定义连接上mqtt处理函数
  print("connected")
  client:publish("nodemcu", "Hello World", 0, 0)  -- 推送一条消息
  client:subscribe("led", 0, function(client) print("subscribe success") end)  -- 订阅一个主题
end

client:connect("www.liefyuan.top", do_mqtt_connect, handle_mqtt_error)

--------------------------------------------------------

function do_mqtt_message(client, topic, data)  -- 定义一个订阅消息接收处理函数
    print(topic .. ": ")
    if data ~= nil then
        if data == '1' then     -- 如果接收的是字符'1'
            gpio.write(pin, gpio.HIGH)    
            print(data)
        else
            gpio.write(pin, gpio.LOW)
            print(data)
        end

    end
end

client:on("message", do_mqtt_message)

---------------------------------------------------------

function do_timer()  -- 定义定时器处理函数
  print("connected")
  client:publish("nodemcu", "hoho", 0, 0) 
end 

tmr.alarm(1, 10000, tmr.ALARM_AUTO, do_timer)

最后增加一个DHT11

led_pin = 0 -- led的引脚0就是D0
dht11_pin = 5  -- dht11的引脚5就是D5
gpio.mode(led_pin, gpio.OUTPUT)

client = mqtt.Client("NodeMCU_Client", 120)

-------------------------------------------------

function handle_mqtt_error(client, reason) -- 定义mqtt错误处理函数
  print("fail reason" .. reason) 
end

function do_mqtt_connect(client)   -- 定义连接上mqtt处理函数
  print("connected")
  client:publish("nodemcu", "Hello World", 0, 0)  -- 推送一条消息
  client:subscribe("led", 1, function(client) print("subscribe success") end)  -- 订阅一个主题
end

client:connect("www.liefyuan.top", do_mqtt_connect, handle_mqtt_error)

--------------------------------------------------------

function do_mqtt_message(client, topic, data)  -- 定义一个订阅消息接收处理函数
    print(topic .. ": ")
    if data ~= nil then
        if data == '1' then     -- 如果接收的是字符'1'
            gpio.write(led_pin, gpio.HIGH)    
            print(data)
        else
            gpio.write(led_pin, gpio.LOW)
            print(data)
        end

    end
end

client:on("message", do_mqtt_message)

---------------------------------------------------------

function do_timer()  -- 定义定时器处理函数
  print("connected")
  client:publish("nodemcu", "hoho", 0, 0) 
end 

tmr.alarm(1, 10000, tmr.ALARM_AUTO, do_timer)

-----------------------------------------------------------

function do_timer_getdht11()  -- 定义定时器处理函数
  status, temp, humi, temp_dec, humi_dec = dht.read(dht11_pin)
    if status == dht.OK then
        -- Integer firmware using this example
        print(string.format("DHT Temperature:%d.%03d;Humidity:%d.%03drn",
              math.floor(temp),
              temp_dec,
              math.floor(humi),
              humi_dec
        ))

        -- Float firmware using this example
        --print("DHT Temperature:"..temp..";".."Humidity:"..humi)

    elseif status == dht.ERROR_CHECKSUM then
        print( "DHT Checksum error." )
    elseif status == dht.ERROR_TIMEOUT then
        print( "DHT timed out." )
    end  
end 

tmr.alarm(2, 1000, tmr.ALARM_AUTO, do_timer_getdht11)

-----------------------------------------------------------

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