由于自己的新房子正在装修，所以想DIY一个室内空气质量检测系统来观察家里VOC污染情况，同时想了解下温度、湿度和VOC释放量的关系。好吧看看都需要些神马器件吧？
1.nodemcu V3
2.VOC传感器
3.DHT11温湿度传感器
4.OLED 128*64 SSD1306

原理图：
其中OLED和VOC传感器采用的是I2C接线方式。
nodemcu采用micropython编程代码如下：

import machine
import micropython
import ujson
import utime
import ustruct
import dht
import ubinascii
import gc
from machine import Timer
import ssd1306
import network
from machine import WDT


# ESP8266 ESP-12 modules have blue, active-low LED on GPIO2, replace
# with something else if needed.
#led = machine.Pin(2, machine.Pin.OUT, value=1)
# Default MQTT server to connect to
#SERVER = "183.230.40.39"
            
def pack_data(tmp,hum,voc):
    time = utime.localtime()
    print(time)
    h = time[3]+8
    if h >= 24:
        h = h-24
    now = "%d-%02d-%02d %02d:%02d:%02d"%(time[0],time[1],time[2],h,time[4],time[5])
    print(now)
    data = ujson.dumps({"datastreams":[{"id":"temperature", "datapoints":[{"at":now, "value":tmp}]},{"id":"humidity", "datapoints":[{"at":now, "value":hum}]},{"id":"voc", "datapoints":[{"at":now, "value":voc}]}]})
    print(data)
    gc.collect()
    return data
    #datafmt = "BBB%ds"%len(data)
    #print(datafmt)
    #senddata = ustruct.pack(datafmt, 1,0,len(data), data)
    #print(senddata)
    #return senddata



def get_tmp_hum():
    d = dht.DHT11(machine.Pin(5))
    d.measure()
    tmp = d.temperature()
    hum = d.humidity()
    print(tmp)
    print(hum)
    gc.collect()
    return (tmp,hum)

def get_voc():
    voc = 0.0
    voc_dev = machine.I2C(
    scl = machine.Pin(14), sda = machine.Pin(12), freq = 50000)
    print(voc_dev.scan())
    #voc_dev.init(scl = machine.Pin(14), sda = machine.Pin(12), freq = 100000)
    buf = voc_dev.readfrom(47, 4, True)
    #print(ubinascii.hexlify(buf, ))
    fmt = '>BHB'
    addr,ppm,chk_val = ustruct.unpack(fmt,buf)
    #print (addr,ppm, chk_val)
    if ppm == 65535:
        return None
    voc = ppm*0.1
    print(voc)
    gc.collect()
    return voc


i2c = machine.I2C(scl = machine.Pin(4), sda = machine.Pin(2), freq=100000)
oled = ssd1306.SSD1306_I2C(128, 64, i2c)
oled.poweron()
oled.init_display()
count = 0
wdt = WDT()

def general_display():
    global oled
    global count
    count=count+1
    oled.text('IAQ:'+str(count),1,1)
    wlan = network.WLAN(network.STA_IF)
    ipconfig = wlan.ifconfig()
    oled.text('I:'+ipconfig[0],0,36)
    oled.text('pwd:123456',0,45)
    host = ipconfig[2]
    oled.text('H:'+host, 0, 54)
    gc.collect()

def send_data(addr,data):
    global wdt
    from usocket import *
    try:
        client = socket(AF_INET, SOCK_STREAM)
        client.settimeout(1)
        client.connect(addr)
        client.sendall(data)
        wdt.feed()
        gc.collect()
        return True
    except MemoryError as e:
        print(e)
        pin = machine.Pin(9, machine.Pin.OUT)
        return False
    except Exception as e:
        print(e)
        #chip reset
        pin = machine.Pin(9, machine.Pin.OUT)
        return False
    finally:
        pass
        #pin = machine.Pin(9, machine.Pin.OUT)
        return False

def timer_cb(t = None):
    global oled
    tmp,hum = get_tmp_hum()
    voc = get_voc()
    if voc == None:
        return
    data = pack_data(tmp,hum,voc)
    oled.fill(0)
    general_display()
    oled.text('VOC(ppm):'+str(voc),1,9)
    oled.text('Temp(C):'+str(tmp),1,18)
    oled.text('Hum(%):'+str(hum), 1, 27)
    oled.show()
    host =  wlan = network.WLAN(network.STA_IF)
    ipconfig = wlan.ifconfig()
    host = ipconfig[2]
    send_data((host,9000), data)
    gc.collect()

def do_connect_hostspot():
    sta_if = network.WLAN(network.STA_IF)
    retry = 0
    if not sta_if.isconnected():
        print('connecting to network...')
        sta_if.active(True)
        sta_if.connect('iaq-server', '123456@iaq')
        while not sta_if.isconnected():
            utime.sleep(1)
            retry = retry +1
            #if retry >= 3:
                #break
        print('network config:', sta_if.ifconfig())
    #import ntptime
    #import utime
    #ntptime.settime()
    #print(utime.localtime())
    gc.collect()
    
def main():
    #webrepl.start()
    # Subscribed messages will be delivered to this callback 
    try:
        #webrepl.start()
        #c = MQTTClient(CLIENT_ID, server,6002,username,password)
        #c = MQTTClient("esp8266", server,10008)
       
        #tim = Timer(-1)
        #tim.init(period=10000, mode=Timer.PERIODIC, callback=timer_cb)
        while 1:
            #machine.idle()
            try:
                do_connect_hostspot()
                timer_cb()
                utime.sleep(60)
                gc.collect()
            except Exception as e:
                print(e)
                #chip reset
                pin = machine.Pin(9, machine.Pin.OUT)
            finally:
                pass
    except Exception as e:
        print(e)
    finally:
        pass

main()

代码主要实现了温度、湿度、VOC的收集和显示，并且保存到influxdb方便后续分析，server端nodejs代码如下：

const Influx = require('influx')
const influx = new Influx.InfluxDB({
  host: 'localhost',
  port: 8086,
  database: 'test',
  username:'fanday',
  password:'password',
  schema: [
    {
      measurement: 'iaq',
      fields: {
        temperature: Influx.FieldType.INTEGER,
        humidity: Influx.FieldType.INTEGER,
        voc:Influx.FieldType.FLOAT
      },
      tags: [
        'IAQ'
      ]
    }
  ]
})

var net = require('net');
var IAQServer = net.createServer();
IAQServer.on('connection', function(client){
  console.log('client connected!');
  client.on('data', function(data){
    console.log(data);
    iaqData = JSON.parse(data);
    console.log(iaqData);
    datastreams = iaqData['datastreams'];
    console.log('datastreams:', datastreams);

    var tmp = 0;
    var voc = 0.0;
    var hum = 0;
    datastreams.forEach(function(d){
      console.log('d:',d);
      val = d['datapoints'][0]['value'];
      if(d['id'] == 'temperature'){
        tmp = val;
      }

      if(d['id'] == 'humidity'){
        hum = val;
      }

      if(d['id'] == 'voc'){
        voc = val;
      }
    });
    console.log('temperature:', tmp, 'humidity:', hum,'voc:', voc)
    influx.writePoints([
      {
        measurement: 'iaq',
        fields: { temperature:tmp, humidity: hum, voc:voc },
      }
    ]).catch(err => {
      console.error(`Error saving data to InfluxDB! ${err.stack}`);
    });
    client.end();
  });
});
IAQServer.listen(9000);

源代码地址：
https://github.com/fanday/esp8266-iaq-monitor
有问题可以给我留言。