IAQ_monitor

Indoor Air Quality Monitoring System

Overview

The basic functions of an air quality monitor system are as follows:

• Sensors are used to measure room temperature, humidity, air pressure, and CO2 concentration
• Send data to IoT Platform (ThingSpeak)
• ThingSpeak accumulates historical data
• Graph display using the ThingSpeak data viewer (smartphone app; ThingView)

Appearance of the Indoor Air Quality (IAQ) monitor

M5 Stamp (microcontroller is ESP32 C3(RISC-V)), and the sensors are SCD41 and QMP6988 connected via I2C.

Data viewer(Thingview)

The data is stored in ThingSpeak and can be graphed using Thingview.

System Architecture

• IAQ monitor(M5 Stamp) and ThingSpeak are connected via MQTT
• Publish the data obtained from the sensor
• Past history is stored in IoT PF; ThingSpeak
• ThingSpeak history data can be viewed using the smartphone app (Thingview)

Software Architecture

The software consists of the following:

• scd41.rc Driver for controlling temperature, humidity and CO2 sensor (SCD41)
• qmp6988.rc Driver to control the barometric pressure sensor (QMP6988)
• mylib.rc Subroutines for setting up WiFi/MQTT
• softi2c.rc Since there is only one I2C channel as a peripheral I/O, the missing channel is supplemented with a software version of the I2C Driver.
• main.rc Controls the entire system (obtains data from sensors and publishes it to ThingSpeak)