Arduino air quality analyser

The project:

This is a air analyser programmed with Arduino. It can be used to study air quality. It uses an Arduino Méga board and a Seed studio Grove shield to simplify components connection.

Measures:

• Temperature (°C)
• Pressure (hPa)
• Humidity (%)
• CO2 (ppm)
• Volatile organic compounds = VOC and specialy HCHO (µg/m3)
• Particles PM1 PM2.5 and PM10 (µg/m3)

Data can be:

• displayed on LCD scree
• displayed on computer screen with a Node-Red dashboard
• stored on sd card then displayed on graph with python script.

Sensors connections:

• Grove shield is plugged on Mega board then sd shield is plugged on Grove shield.

• SD Shield is attached to SPI bus as follows:

  • MOSI - pin 11 on sd shield is connected with wire on pin 51 on Mega
  • MISO - pin 12 on sd shield is connected with wire on pin 50 on Mega
  • CLK - pin 13 on sd shield is connected with wire on pin 52 on Méga
  • CS - depends on your SD card shield (pin 10 on my shield).

• SD shield is attached to I2C bus for RTC module as follows:

  • sda pin on sd shield is connected with jumper to A4 pin on sd shield
  • scl pin on sd shield is connected with jumper to A5 pin on sd shield

• HCHO sensor is connected on pin 19 (Rx1) on Mega

• CO2 sensor, lcd display, BME280 sensor and particles sensor are attached to I2C plugs en Grove Shield

• Button is connected on D2 plug on Grove shield

• LED is connected on D3 plug on Grove shield

Installation:

• Install all librarys on Arduino.
• You may need to set time and date on RTC module with RTC_set_time.ino sketch.
• Upload version1.ino sketch on to Mega board.

Functions:

When the program is starting, you have to make a choice between three functions of the analyser:

• display sensor values on the LCD screen;
• data logging on sd card;
• send data to Node-Red thrue serial link.

I use an automat with button as follows to make this choice.

Node-Red:

• See here ton install Node-Red on windows: https://nodered.org/docs/getting-started/windows ; https://nodered.org/docs/getting-started/local

• Mega board is sending data with JSON format thrue serial link to Node-Red.

• Import flows with flows.json-1.txt

• Don't forget to change the Com port name in Serial node.

• You can see flows below

• Then result on realtime dashboard. I use this dashboard to display data in classroom with my students.

Python scripts:

I use python script to display with graph the data stored on sd card.

• First script Graph from csv.py displays one graph per data per window.
• Second script Graph from csv_1graph.py displays many graphs on one window.