Air quality monitor (MQ 5/7/135 based)
An ESP8266 mini based air quality monitor.
Please note that this should never be used to replace a proper CO monitor and should be used for informational purposes only.
Head on over to Thingiverse to grab the .stl files to print.
Parts:
- Wemos D1 mini (amazon.com)
- MQ 5 sensor
- MQ 7 sensor
- MQ 135 sensor
- ADS1115 ADC Analog to Digital Converter (amazon.com)
- M2.5 brass inserts (amazon.com)
- M2.5 screws and nuts (amazon.com)
- Hook up wire
- Heat shrink
Build guide
Step 1 – Print the back and use a soldering iron to insert the 14 x M2.5 brass insert nuts.
Step 2 – Use M2.5 screws to mount the MQ 5/7/135 sensors, analog to digital converter and Wemos D1 mini.
Step 3 – Connect everything together. This requires a lot of patience.
Step 4 – Time to get coding. Head over to ESPHome in Home Assistant and use the following code as a starting point. You’ll need to update some of the values and calibrate the sensors.
YAML
esphome:
name: air-quality-monitor
esp8266:
board: d1_mini
# Enable logging
logger:
# Enable Home Assistant API
api:
encryption:
key: "<your_key_here>"
ota:
password: "<your_password_here>"
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
# Enable fallback hotspot (captive portal) in case wifi connection fails
ap:
ssid: "Air-quality-monitor Fallback Hotspot"
password: "6JCdx#QryWEH6t!a%&@h"
captive_portal:
i2c:
sda: D3
scl: D4
scan: true
id: db_busa
ads1115:
# continuous_mode : on
- address: 0x48
id: ads1115_48
continuous_mode: on
sensor:
- name: "boiler_mq5_flammable_gas_sensor"
id: boiler_mq5_flammable_gas_sensor #ads1115_48_a0
ads1115_id: ads1115_48
multiplexer: 'A0_GND'
gain: 6.144
platform: ads1115
accuracy_decimals: 2
update_interval: 30s
filters:
lambda: return (x/5 *100);
unit_of_measurement: "%"
- name: "boiler_mq7_co_sensor"
id: boiler_mq7_co_sensor #ads1115_48_a1
ads1115_id: ads1115_48
multiplexer: 'A1_GND'
gain: 6.144
platform: ads1115
accuracy_decimals: 2
update_interval: 30s
filters:
lambda: return (x/5 *100);
unit_of_measurement: "%"
- name: "boiler_mq135_harmful_gas_sensor"
id: boiler_mq135_harmful_gas_sensor #ads1115_48_a2
ads1115_id: ads1115_48
multiplexer: 'A2_GND'
gain: 6.144
platform: ads1115
accuracy_decimals: 2
update_interval: 30s
filters:
lambda: return (x/5 *100);
unit_of_measurement: "%" Expand
Step 5 – Print the lid, screw it on and you’re ready to go.
*The product links in this post may contain affiliate links. I donate 20% of these earnings to the Good Work Foundation to help innovate learning in South Africa’s rural communities.
Thanks for making it to the end of the post!
Hi,
Can you please share the simple schematic wiring from each sensor to adc and d1? I cant find it in the article and its too dificult to guess it from the picture.
It really helpful for newbie like me 🙂
Thanks for this great project.