NodeMCU--MQTT学习笔记（一）
官方文档：https://nodemcu.readthedocs.io/en/master/en/modules/mqtt/
| 函数 | 函数简介 |
|---|---|
| mqtt.Client() | 创建一个MQTT客户端 |
| mqtt.client:close() | 关闭与MQTT服务器的连接 |
| mqtt.client:connect() | 连接到MQTT服务器并指定主机、端口和安全选项 |
| mqtt.client:lwt() | 建立遗嘱(可选的) |
| mqtt.client:on() | 注册一个回调函数的事件 |
| mqtt.client:publish() | 发布消息 |
| mqtt.client:subscribe() | 订阅一个或多个主题 |
| mqtt.client:unsubscribe() | 退订一个或几个主题 |
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.%03d\r\n",
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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