32. MQ3 Gas Sensor

32.1. Introduction

The MQ3 Gas sensor is tin dioxide (SnO2), which has a low conductivity in clean air. While the sensor being put in an environment that exists the alcohol vapor, the electrical conductivity of the sensor increases as the concentration of alcohol gas in the air increases.

microbitplanetX\./images/05032_01.png

32.2. Characteristic


  • Designed in RJ11 connections, easy to plug.

32.3. Specification


Item Parameter
SKU EF05032
Connection RJ11
Type of Connection Analog output
Working Voltage 3.3V

32.4. Outlook


microbitplanetX\./images/05032_02.png

32.5. Quick to Start


Materials Required and Diagram


  • Connect the MQ3 Gas sensor to J1 port and the OLED to the IIC port in the Nezha expansion board as the picture shows.

microbitplanetX\./images/05032_03.png

Note: A preheating for 3 minutes after powering on is required before using.

32.6. MakeCode Programming


Step 1

Click “Advanced” in the MakeCode drawer to see more choices.

../_images/05001_04.png

We need to add a package for programming, . Click “Extensions” in the bottom of the drawer and search with “PlanetX” in the dialogue box to download it.

../_images/05001_05.png

Note: If you met a tip indicating that the codebase will be deleted due to incompatibility, you may continue as the tips say or build a new project in the menu.

Step 2

Code as below:

../_images/05032_06.png

Result

  • The value detected from MQ3 Gas sensor displays on the OLED screen.

32.7. Python Programming


Step 1

Download the package and unzip it: PlanetX_MicroPython

Go to Python editor

../_images/05001_072.png

We need to add enum.py and ethanol.py for programming. Click “Load/Save” and then click “Show Files (1)” to see more choices, click “Add file” to add enum.py and ethanol.py from the unzipped package of PlanetX_MicroPython.

../_images/05001_081.png ../_images/05001_091.png ../_images/05032_10.png

Step 2

Reference

from microbit import *
from enum import *
from ethanol import *
ethanol = ETHANOL(J1)
while True:
    display.scroll(ethanol.get_ethanol())

Result

  • The value detected from MQ3 Gas sensor displays on the micro:bit.

32.8. Relevant File


32.9. Technique File