NodeMCU

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NodeMCU是一个开源的物联网平台。它使用Lua脚本语言编程。该平台基于eLua 开源项目,底层使用ESP8266 sdk 0.9.5版本。该平台使用了很多开源项目, 例如 lua-cjson, spiffs. NodeMCU包含了可以运行在 esp8266 Wi-Fi SoC芯片之上的固件,以及基于ESP-12模组的硬件。

## History

NodeMCU is started after ESP8266 come out. In December 30, 2013, Espressif systems begin production of ESP8266. ESP8266 is an Wi-Fi SoC and integrated with LX106 core, widely used in IoT applications(See related projects). In 13 Oct 2014, Hong committed first file of nodemcu-firmware to github, NodeMCU project started. And then more and more developers from ESP8266 opensource community join in NodeMCU developer team. On 1 Dec 2014, Huang R commit the gerber file of an ESP8266 board, then NodeMCU project have the first open-hardware which named devkit 1.0, thus NodeMCU is not only a firmware, it becomes a platform. In 31 Dec 2014, Tuan PM port MQTT client library from Contiki to ESP8266 SoC platform, and commit to NodeMCU project, then NodeMCU can support MQTT IoT protocol, using Lua access MQTT broker, it is an important update of firmware. Another important update is in 30 Jan 2015, Devsaurus port u8glib to NodeMCU project, and NodeMCU can drive LCD, Screen, OLED, even VGA display module easily.

## Pins脚

NodeMCU 提供对 GPIO（通用输入/输出）的存取控制，并且引脚映射表是 API 文件的一部分。

I/O index｜ESP8266 pin

0、｜GPIO16

1｜GPIO5

2｜GPIO4

3｜GPIO0

4｜GPIO2

5｜GPIO14

6｜GPIO12

7｜GPIO13

8｜GPIO15

9｜GPIO3

10｜GPIO1

11｜GPIO9

12｜GPIO10

- D0 (GPIO16) 只能用于GPIO读/写。它不支援open-drain/interrupt/PWM/I²C 或 1-Wire。

## 硬件连接

如果使用 NodeMCU devkit, 只需要安装 CH340G 驱动程式, 并且将开发模组使用micro-usb 线连接到电脑。然后，将波特率设为9600, 并打开序列埠。若使用普通的esp8266模组, 则必须准备usb-ttl 转接器。

## 固件烧写

nodemcu_latest.bin: 0x00000 对于大多数 esp8266 模块, 直接拉低 GPIO0 引脚的电平，并且重新上电或重启。可以使用 nodemcu-flasher 烧写固件。

特别的，如果你想编译/构建自己的固件，需要注意以下烧写地址： 0x00000.bin: 0x00000 0x10000.bin: 0x10000

注意，在烧写之后，最好执行 file.format

## 程式举例

### 连接Wi-Fi热点

```lua
    ip = wifi.sta.getip()
    print(ip)
    --nil
    wifi.setmode(wifi.STATION)
    wifi.sta.config("SSID","password")
    ip = wifi.sta.getip()
    print(ip)
    --192.168.18.110
```

### 如同arduino般操作硬体

```lua
    pin = 1
    gpio.mode(pin,gpio.OUTPUT)
    gpio.write(pin,gpio.HIGH)
    print(gpio.read(pin))
```

### 使用 nodejs 风格网络编程

```lua
    -- A simple http client
    conn=net.createConnection(net.TCP, 0)
    conn:on("receive", function(conn, payload) print(payload) end )
    conn:connect(80,"115.239.210.27")
    conn:send("GET / HTTP/1.1\r\nHost: www.baidu.com\r\n"
        .."Connection: keep-alive\r\nAccept: */*\r\n\r\n")
```

### 简易的HTTP服务器

```lua
    -- A simple http server
    srv=net.createServer(net.TCP)
    srv:listen(80,function(conn)
      conn:on("receive",function(conn,payload)
        print(payload)
        conn:send("<h1> Hello, NodeMcu.</h1>")
      end)
      conn:on("sent",function(conn) conn:close() end)
    end)
```

### 连接 MQTT Broker

```lua
-- init mqtt client with keepalive timer 120sec
m = mqtt.Client("clientid", 120, "user", "password")

-- setup Last Will and Testament (optional)
-- Broker will publish a message with qos = 0, retain = 0, data = "offline"
-- to topic "/lwt" if client don't send keepalive packet
m:lwt("/lwt", "offline", 0, 0)

m:on("connect", function(con) print ("connected") end)
m:on("offline", function(con) print ("offline") end)

-- on publish message receive event
m:on("message", function(conn, topic, data)
  print(topic .. ":" )
  if data ~= nil then
    print(data)
  end
end)

-- for secure: m:connect("192.168.11.118", 1880, 1)
m:connect("192.168.11.118", 1880, 0, function(conn) print("connected") end)

-- subscribe topic with qos = 0
m:subscribe("/topic",0, function(conn) print("subscribe success") end)
-- or subscribe multiple topic (topic/0, qos = 0; topic/1, qos = 1; topic2 , qos = 2)
-- m:subscribe({["topic/0"]=0,["topic/1"]=1,topic2=2}, function(conn) print("subscribe success") end)
-- publish a message with data = hello, QoS = 0, retain = 0
m:publish("/topic","hello",0,0, function(conn) print("sent") end)

m:close();
-- you can call m:connect again
```

### UDP 客户端与服务器

```lua
-- a udp server
s=net.createServer(net.UDP)
s:on("receive",function(s,c) print(c) end)
s:listen(5683)

-- a udp client
cu=net.createConnection(net.UDP)
cu:on("receive",function(cu,c) print(c) end)
cu:connect(5683,"192.168.18.101")
cu:send("hello")
```

## 基本资料

- 开发者：ESP8266开源社区
- 类型：片上系统
- 中央处理器：ESP8266(LX106)
- 存储：4MBytes
- 内存：20kBytes
- 操作系统：XTOS
- 功耗：USB
- 网站：http://www.nodemcu.com