First NodeMCU Project

说起物联网，最早接触的是Arduino。可是入手Arduino Mega后，一直没做出什么好玩的东西，以致Mega丢在角落里好几年。近来在部门经理的怂恿下，入手了NodeMCU，做了个检测盆栽的土壤湿度。本来想在Github开个项目，但是这第一版太简单了，就随便记录一下。

NodeMCU的特点，在于自带WiFi（还可以使用AP模式），而且价格便宜。当然，缺点也在WiFi，比较耗电。为了省电，可以设置网卡的硬件参数（wifi.setphymode()），关闭WiFi（wifi.sleeptype()），甚至是整块板进入深度睡眠模式（node.dsleep(), rtctime.dsleep())。其开源、基于Lua的开发简单、尺寸迷你等优点，也是其好玩之处。

这个项目很简单，就是NodeMCU连个土壤湿度检测模块，定时（10分钟）获取一次数据，并上传到服务器。服务器是采用树梅派，用Python3，利用Flask框架，写了个HTTP服务，用于保存提交的数据，并做数据展示。数据都保存在MySQL数据库。

NodeMCU上的init.lua

print("\n")
print("ESP8266 Started")

dsleepTime = 630000000
ssid = "my-wifi"
password = "123456"
serverIp = "192.168.1.1"
serverPort = 8080

wifi.setphymode(wifi.PHYMODE_N)
wifi.setmode(wifi.STATION)
wifi.sta.config(ssid, password)
tmr.alarm(0,1000,1,function() 
    curIp = wifi.sta.getip()
    if curIp ~= nil then
        print("Current IP:"..curIp)
        tmr.stop(0)
        sendData(readValue(0, 5))
    end
end)

--发送数据到服务器    
function sendData(value)
    print("sendData start")
    conn = net.createConnection(net.TCP, false)
    conn:on("receive", function(conn, pl)
        print("Send data with value: "..value)
        print("Result:\n"..pl)
        conn:close()
        conn = nil
        wifi.sta.disconnect()
        
        node.dsleep(dsleepTime)
    end)
    conn:connect(serverPort, serverIp)
    conn:send("GET /gather/?key=123456&value="..value
        .." HTTP/1.1\r\nHost: " + serverIp + "\r\n"
        .."Connection: keep-alive\r\nAccept: */*\r\n\r\n")

    --connect time out
    tmr.alarm(1,5000,1,function()
        print("[error]connet to server time out")
        --conn:close()
        --conn = nil
        --wifi.sta.disconnect()
        tmr.stop(1)
        
        node.dsleep(dsleepTime)
    end)
end

--读取土壤湿度数据
--一次有效的采样，最少取3次数据，去掉最大值和最小值，再计算平均值
function readValue(adcPin, readTimes)
    if readTimes <= 2 then
        readTimes = 3
    end
    
    local curValue = 0
    local maxValue = 0
    local minValue = 0
    local sumValue = 0
    
    for i = 0, readTimes - 1 do
        curValue = adc.read(adcPin)
        sumValue = sumValue + curValue
        if maxValue < curValue then
            maxValue = curValue
        end
        if (minValue == 0) or (minValue > curValue) then
            minValue = curValue
        end
    end
    sumValue = sumValue - maxValue - minValue
    curValue = math.floor(sumValue / (readTimes - 2))

    return curValue
end

服务器上的HTTP服务，文件site.ini

[uwsgi]
socket = 127.0.0.1:8080
processes = 2
threads = 1
plugins = python3
master = true
pythonpath = /opt/work/web_gather
chdir = /opt/work/web_gather
module = site
callable = app
chmod-socket = 777
memory-report = true

服务器上的HTTP服务，文件site.py

#!/bin/python3

from datetime import datetime
from flask import Flask, request, abort, render_template
from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy import desc

app = Flask(__name__)
app.config['SECRET_KEY'] = '123456'

app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:123456@127.0.0.1/web_gather'
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True

app.config['HUMIDITY_MIN'] = 740

db = SQLAlchemy(app)

class Humidity(db.Model):
    __tablename__ = 'humidity'
    id = db.Column('id', db.Integer, primary_key=True)
    createDate = db.Column('create_date', db.DateTime)
    sourceValue = db.Column('source_value', db.Integer)
    value = db.Column('value', db.Integer)

    def __repr__(self):
        return '<Humidity % r>' % self.id

@app.route('/', methods=['GET', 'POST'])
def index():
    key = request.args.get('key', '')
    
    if key == app.config['SECRET_KEY']:
        sourceValue = request.args.get('value', '0')
        value = (1024 - int(sourceValue)) / 1024 * 100
        curTime = datetime.today()
        humidity = Humidity(createDate=curTime, sourceValue=sourceValue, value=value)
        db.session.add(humidity)
        db.session.commit()
        return 'true'
    
    humidities = Humidity.query.order_by(desc(Humidity.createDate)).limit(500)
    return render_template('humidity.html', humidities=humidities)

if __name__ == '__main__':
    app.run(debug=False, host='127.0.0.1', port=8080)
    #app.debug = False
    #app.run()

MySQL的表定义

CREATE TABLE `humidity` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `create_date` datetime DEFAULT NULL,
  `source_value` int(11) DEFAULT NULL,
  `value` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2554 DEFAULT CHARSET=utf8