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前言

此篇为番外篇,是 ESP8266 入门的其他功能教程,包括但不限于

1. DHT11 驱动
2. TCP 通信
3. Thingsboard 平台的接入
4. 阿里云物联网云平台接入
5. 华为云平台接入

1. 小节目标

使用 Lua 驱动 DHT11 传感器,获取温湿度的值

2. 进入主题

NodeMCU 基于 LUA 相关资料

官方文档：dht - NodeMCU Documentation

包括 dht 的固件：📎nodemcv_dht.zip

如果使用的是以下这一款硬件，就直接使用引脚4

2.1. 单独驱动温湿度传感器

dht11Pin = 4

tmr.create():alarm(3000,tmr.ALARM_AUTO ,function()
    if conn_flag==1 then
        status, 
        temp, 
        humi, 
        temp_dec,
        humi_dec = dht.read(dht11Pin)
        if status == dht.OK then  --根据返回的状态
          dht11data=string.format("DHT Temperature:%d.%03d;Humidity:%d.%03d\r\n")
          -- 打印
          print(dht11data)
          -- 在这里直接发送到MQTT上
        else 
        print("dht11 error")
        -- 下面这一行是上报到物联网云平台的,如果不想上报直接打印即可
        -- m:publish(pub_topic,"[dht11 error",0, 0, function(client) print("sent") end)
        end
    end
 end)

2.2. 完整代码

station_cfg = {}
station_cfg.ssid = "wifi_ssid"
station_cfg.pwd  = "wifi_pwd"

station_cfg.auto = false
station_cfg.save = false

-- MQTT配置
mqtt_cfg = {}
mqtt_cfg.host      = "broker.emqx.io"
mqtt_cfg.port      = 1883
mqtt_cfg.clientid  = "alro12345940"
mqtt_cfg.keepalive = 120
mqtt_cfg.username  = "AlvaRocha"
mqtt_cfg.password  = "aio_KO<safety edit>sXwbgtWCboCal"
sub_topic="/topic/ctiot/dht11/topic/c"
pub_topic="/topic/ctiot/dht11/topic/m"
m=nil
iot_test = mqtt.Client(mqtt_cfg.clientid, mqtt_cfg.keepalive, mqtt_cfg.username, mqtt_cfg.password)

-- wifi配置
wifi.setmode(wifi.STATION)
wifi.sta.config(station_cfg)



-- gpio 配置
pin=3
gpio.mode(pin, gpio.OUTPUT)

conn_flag=0

function get_broker(mqtt_client)
  mqtt_client:connect(mqtt_cfg.host, mqtt_cfg.port, false,
    function(client)
      client:subscribe(sub_topic, 0, function(client)
        print("subscribe success ",  sub_topic)
        
      end)
         m:publish(pub_topic, "success", 0, 0, function(client)
         print("init success")
         conn_flag=1
      end)
    end,
    function(client, reason)
      print('connection failed', reason)
    end)
    m=mqtt_client
end

iot_test:on("offline", function(client)
  print("client offline")
  conn_flag=0
  get_broker(iot_test)
end)
iot_test:on("message", function(client, topic, data)
  --print("MQTT msg received on '" .. topic .. "':")
  if data ~= nil 
  then
    print(data)
    if data == "1"
    then
      gpio.write(pin, gpio.HIGH)
      print("1111")
    end
    if data == "2"
    then
      gpio.write(pin,gpio.LOW)
      print("222")
    end
  end
end)



function startup()
  if file.open("init.lua") == nil then
    --print("init.lua deleted or renamed")
  else
    --print("Running")
    file.close("init.lua")
    get_broker(iot_test)
  end
end

wifi_connect_event = function(T)
  print("Connection to AP(" .. T.SSID .. ") established!")
  print("Waiting for IP address...")
  if disconnect_ct ~= nil then
    disconnect_ct = nil
  end
end

wifi_got_ip_event = function(T)
  tmr.create():alarm(3000, tmr.ALARM_SINGLE, startup)
end

wifi.eventmon.register(wifi.eventmon.STA_CONNECTED, wifi_connect_event)
wifi.eventmon.register(wifi.eventmon.STA_GOT_IP, wifi_got_ip_event)
wifi.eventmon.register(wifi.eventmon.STA_DISCONNECTED, function(T)
  wifi.sta.connect()
end)
wifi.sta.connect()

dht11Pin = 4

tmr.create():alarm(3000,tmr.ALARM_AUTO ,function()
    if conn_flag==1 then
        status, 
        temp, 
        humi, 
        temp_dec,
        humi_dec = dht.read(dht11Pin)
        if status == dht.OK then  --根据返回的状态
           m:publish(pub_topic, string.format("DHT Temperature:%d.%03d;Humidity:%d.%03d\r\n",
          math.floor(temp),
          temp_dec,
          math.floor(humi),
          humi_dec
    ),
           0, 0, function(client) print("sent") end)
        else 
        print("dht11 error")
        m:publish(pub_topic,"[dht11 error",0, 0, function(client) print("sent") end)
        end
    end
 end)

3. 完整的代码注释

为了方便各位读者学习,特地将代码加上注释,如下

-- Wi-Fi连接配置
station_cfg = {}
station_cfg.ssid = "wifi_ssid"  -- 设置Wi-Fi的SSID
station_cfg.pwd  = "wifi_pwd"   -- 设置Wi-Fi的密码
station_cfg.auto = false        -- 设置Wi-Fi不自动连接
station_cfg.save = false        -- 设置不保存Wi-Fi连接信息

-- MQTT连接配置
mqtt_cfg = {}
mqtt_cfg.host      = "broker.emqx.io"           -- 设置MQTT服务器地址
mqtt_cfg.port      = 1883                        -- 设置MQTT服务器端口
mqtt_cfg.clientid  = "alro12345940"          -- 设置MQTT客户端ID
mqtt_cfg.keepalive = 120                           -- 设置MQTT保持连接时间
mqtt_cfg.username  = "AlvaRocha"            -- 设置MQTT用户名
mqtt_cfg.password  = "aio_KO<safety edit>sXwbgtWCboCal" -- 设置MQTT密码
sub_topic="/topic/ctiot/dht11/topic/c"      -- 设置MQTT订阅主题
pub_topic="/topic/ctiot/dht11/topic/m"      -- 设置MQTT发布主题

-- 初始化MQTT客户端
m=nil
iot_test = mqtt.Client(mqtt_cfg.clientid, mqtt_cfg.keepalive, mqtt_cfg.username, mqtt_cfg.password)

-- 设置Wi-Fi模式为Station模式并配置Wi-Fi连接参数
wifi.setmode(wifi.STATION)
wifi.sta.config(station_cfg)

-- 配置GPIO引脚
pin=3
gpio.mode(pin, gpio.OUTPUT)

conn_flag=0  -- 初始化连接标志为0

-- 连接到MQTT服务器并订阅主题的函数
function get_broker(mqtt_client)
  mqtt_client:connect(mqtt_cfg.host, mqtt_cfg.port, false,
    function(client)
      client:subscribe(sub_topic, 0, function(client)
        print("subscribe success ",  sub_topic)
      end)
      -- 发布初始化成功消息
      m:publish(pub_topic, "success", 0, 0, function(client)
         print("init success")
         conn_flag=1
      end)
    end,
    function(client, reason)
      print('connection failed', reason)
    end)
    m=mqtt_client
end

-- MQTT客户端离线时的回调函数
iot_test:on("offline", function(client)
  print("client offline")
  conn_flag=0
  get_broker(iot_test)
end)

-- MQTT客户端接收到消息时的回调函数
iot_test:on("message", function(client, topic, data)
  if data ~= nil then
    print(data)
    if data == "1" then
      gpio.write(pin, gpio.HIGH)
      print("1111")
    end
    if data == "2" then
      gpio.write(pin,gpio.LOW)
      print("222")
    end
  end
end)

-- 设备启动时执行的操作
function startup()
  if file.open("init.lua") == nil then
    --print("init.lua deleted or renamed")
  else
    --print("Running")
    file.close("init.lua")
    get_broker(iot_test)
  end
end

-- Wi-Fi连接成功时的事件处理函数
wifi_connect_event = function(T)
  print("Connection to AP(" .. T.SSID .. ") established!")
  print("Waiting for IP address...")
  if disconnect_ct ~= nil then
    disconnect_ct = nil
  end
end

-- 获取到IP地址时的事件处理函数
wifi_got_ip_event = function(T)
  tmr.create():alarm(3000, tmr.ALARM_SINGLE, startup)
end

-- 注册Wi-Fi事件监听器
wifi.eventmon.register(wifi.eventmon.STA_CONNECTED, wifi_connect_event)
wifi.eventmon.register(wifi.eventmon.STA_GOT_IP, wifi_got_ip_event)
wifi.eventmon.register(wifi.eventmon.STA_DISCONNECTED, function(T)
  wifi.sta.connect()
end)
wifi.sta.connect()

-- DHT11传感器引脚配置
dht11Pin = 4

-- 定时执行DHT11传感器读取并向MQTT服务器发布数据
tmr.create():alarm(3000,tmr.ALARM_AUTO ,function()
    if conn_flag==1 then
        status, temp, humi, temp_dec, humi_dec = dht.read(dht11Pin)
        if status == dht.OK then
           m:publish(pub_topic, string.format("DHT Temperature:%d.%03d;Humidity:%d.%03d\r\n",
          math.floor(temp),
          temp_dec,
          math.floor(humi),
          humi_dec
    ),
           0, 0, function(client) print("sent") end)
        else 
        print("dht11 error")
        m:publish(pub_topic,"[dht11 error",0, 0, function(client) print("sent") end)
        end
    end
 end)

4. 结语

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本小节完成了以下功能:

1. 配置Wi-Fi连接参数，使设备能够连接到指定的Wi-Fi网络。
2. 配置MQTT连接参数，使设备能够使用MQTT协议与远程服务器通信。
3. 设置GPIO引脚的模式和状态，以便设备可以控制外部设备。
4. 连接到MQTT服务器并订阅特定主题，以便实时接收来自服务器的消息。
5. 当设备收到MQTT消息时，根据消息内容执行相应的操作，例如控制GPIO引脚的状态。
6. 在设备启动时执行初始化操作，包括连接到Wi-Fi网络和MQTT服务器。
7. 注册Wi-Fi事件监听器，以处理Wi-Fi连接状态变化事件。
8. 通过DHT11传感器定时读取环境温湿度数据，并将数据发布到指定的MQTT主题上。

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