NodeMCU

An arduino sketch that connects a

• MQ-135 air quality sensor

• DHT-11 temperature/humidity sensor

• KY-037 microphone

  To an MQTT broker

Installation

Load up your Arduino IDE

Install ESP8266 board via board manager

Select the correct board (NodeMCU 1.0 (ESP-12E Module))

Install the following libraries via Library manager:

• MQ135.h
• DHT.h
• ESP8266 library
• ESPAsyncTCP
• MQTT Async Library - add to your Arduino library folder

Useful tools for flashing NodeMCU

• NodeMCU Firmware - Use default settings and yes, give up that email address
• NodeMCU Flasher

Hit compile and if successful, upload

To get accurate MQ135 data, you will have to read the rzero value (published by MQTT) with the sensor in a 'neutral' environment

Then update MQ135.h with the new rzero value and reflash the device. If not, your PPM values for air quality may be really high or really low. Normal value should be between 400 to 800 ppm depending on your environemnt (400ppm would be the standard in Melbourne suburbia)