Sharing my experiences

Hardware extensions
#1

My Airgradient project is finally finished. I made some adjustments that I would like to share with you.

  • The air quality index (AQI) is displayed in Home Assistant and is calculated based on the values of the CO2 sensor and the PM sensor.
  • I have built in a status RGB LED (WS2812B) that indicates the status of the Air Quality Index with three colors: green, orange and red. This LED is connected to GPIO15.
  • The life of the PMS5003 sensor has been extended by using the SET functionality. See my other article: Extending the life span of the PMS5003 sensor for more information.
  • I used the design from ttielemans for the case. Instead of connecting the power directly to the ESP module, it is fed into the back of the housing via a USB cable.

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The project runs on ESPHome software. Below the code:

# Instructions: https://esphome.io/guides/getting_started_hassio.html
esphome:
  name: airgradient

esp8266:
  board: d1_mini

# Enable logging
logger:

# Enable Home Assistant API
api:
  password: !secret API_Password

ota:
  safe_mode: true
  password: !secret OTA_Password

# https://esphome.io/components/wifi.html
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  fast_connect: true
  manual_ip:
    static_ip: 192.168.3.12
    gateway: 192.168.3.1
    subnet: 255.255.255.0

captive_portal:

# Configuration for AirGradient DIY v2 device
# https://www.esphome-devices.com/devices/AirGradient-DIY/

# https://esphome.io/components/uart.html#uart
uart:
  - rx_pin: D4
    tx_pin: D3
    baud_rate: 9600
    id: senseair_s8_uart

  - rx_pin: D5
    tx_pin: D6
    baud_rate: 9600
    id: pms5003_uart

i2c:
  sda: D2
  scl: D1
  
sensor:
    # https://esphome.io/components/sensor/pmsx003.html?highlight=pms5003
  - platform: pmsx003
    type: PMSX003
    uart_id: pms5003_uart
    pm_1_0:
      name: "Airgradient PM <1.0µm"
      id: pm1
      filters:
        - sliding_window_moving_average:
            window_size: 30
            send_every: 30
    pm_2_5:
      name: "Airgradient PM <2.5µm"
      id: pm2_5
      filters:
        - sliding_window_moving_average:
            window_size: 30
            send_every: 30
    pm_10_0:
      name: "Airgradient PM <10.0µm"
      id: pm10
      filters:
        - sliding_window_moving_average:
            window_size: 30
            send_every: 30

    # https://esphome.io/components/sensor/senseair.html
  - platform: senseair
    co2:
      name: "Airgradient CO2"
      id: co2
    update_interval: 60s
    uart_id: senseair_s8_uart

    # https://esphome.io/components/sensor/sht3xd.html?highlight=sht31
  - platform: sht3xd
    temperature:
      name: "Airgradient Temperature"
      id: temp
      filters:
        - offset: -1.5
    humidity:
      name: "Airgradient Humidity"
      id: humidity
      filters:
        - offset: +3
    address: 0x44
    update_interval: 60s
    
    # The WHO guidelines work with 24-hour averages of the PM2.5 and PM10 sensors
  - platform: template
    name: "Airgradient PM <2.5µm 24h average"
    id: pm2_5_avg_24h
    icon: mdi:chemical-weapon
    unit_of_measurement: µg/m³
    lambda: |-
      return id(pm2_5).state;
    update_interval: 60s
    filters:
      - sliding_window_moving_average:
          window_size: 1440  # = 24 hours x 60 minutes
          send_every: 1
    on_value:
      then:
        - script.execute: update_aqi
  - platform: template
    name: "Airgradient PM <10.0µm 24h average"
    id: pm10_avg_24h
    icon: mdi:chemical-weapon
    unit_of_measurement: µg/m³
    lambda: |-
      return id(pm10).state;
    update_interval: 60s
    filters:
      - sliding_window_moving_average:
          window_size: 1440  # = 24 hours x 60 minutes
          send_every: 1
    on_value:
      then:
        - script.execute: update_aqi

# A textual presentation of the AQI: goed, matig, slecht
text_sensor:
  - platform: template
    name: "Airgradient Air Quality Index"
    id: aqi
    icon: mdi:air-filter
    
# This script is called on every update of the relevant sensor values.
script:
  - id: update_aqi
    mode: restart
    then:
      # Bad if at least one of the sensor values is bad
      - if:
          condition:
            or:
              - sensor.in_range:
                  id: co2
                  above: 1199
              - sensor.in_range:
                  id: pm2_5_avg_24h
                  above: 25
              - sensor.in_range:
                  id: pm10_avg_24h
                  above: 50
          then:
            - text_sensor.template.publish:
                id: aqi
                state: Slecht
            - script.execute: show_bad
          else:
            # Acceptable if at least one of the sensor values is acceptable
            - if:
                condition:
                  or:
                    - sensor.in_range:
                        id: co2
                        above: 899
                    - sensor.in_range:
                        id: pm2_5_avg_24h
                        above: 12
                    - sensor.in_range:
                        id: pm10_avg_24h
                        above: 25
                then:
                  - text_sensor.template.publish:
                      id: aqi
                      state: Matig
                  - script.execute: show_acceptable
                else:
                  # Otherwise good (all of the sensor values are good)
                  - text_sensor.template.publish:
                      id: aqi
                      state: Goed
                  - script.execute: show_good

    # Configuration for showing AQI status with the RGB LED
  - id: show_bad
    then:
      - light.turn_on:
          id: status_led
          brightness: 25%
          red: 100%
          green: 0%
          blue: 0%
  - id: show_acceptable
    then:
      - light.turn_on:
          id: status_led
          brightness: 25%
          red: 100%
          green: 60%
          blue: 0%
  - id: show_good
    then:
      - light.turn_on:
          id: status_led
          brightness: 25%
          red: 0%
          green: 100%
          blue: 0%
                
display:
  - platform: ssd1306_i2c
    # https://esphome.io/components/display/ssd1306.html?highlight=display
    model: "SSD1306 64x48"
    id: oled_display
    reset_pin: D0
    address: 0x3C
    rotation: 180
    # rotation: 180 # Enable to 180 to flip screen around
    pages:
      - id: display_pm2
        lambda: |-
          it.print(0, 0, id(font1), "PM2,5");
          it.printf(64, 24, id(font1), TextAlign::TOP_RIGHT, "%.0f",id(pm2_5).state);
      - id: display_pm10
        lambda: |-
          it.print(0, 0, id(font1), "PM10");
          it.printf(64, 24, id(font1), TextAlign::TOP_RIGHT, "%.0f",id(pm10).state);    
      - id: display_co2
        lambda: |-
          it.print(0, 0, id(font1), "CO2");
          it.printf(64, 24, id(font1), TextAlign::TOP_RIGHT, "%.0f",id(co2).state);
      - id: display_temp
        lambda: |-
          it.print(0, 0, id(font1), "°C");
          it.printf(64, 24, id(font1), TextAlign::TOP_RIGHT, "%.1f",id(temp).state);
      - id: display_humidity
        lambda: |-
          it.print(0, 0, id(font1), "HUM");
          it.printf(64, 24, id(font1), TextAlign::TOP_RIGHT, "%.0f%%",id(humidity).state);

font:
    # Font to use on the display
    # Open Source font Liberation Sans by Red Hat
    # https://www.dafont.com/liberation-sans.font
  - file: './fonts/liberation_sans/LiberationSans-Regular.ttf'
    id: font1
    size: 22
    
interval:
  - interval: 3s
    # Cycle through page on display
    then:
      - display.page.show_next: oled_display
      - component.update: oled_display
  - interval: 120s
    # Two-minute interval to extend the life span of the PMS5003 sensor
    then:
      - switch.turn_on: pms_set
      - delay: 20s
      - switch.turn_off: pms_set
      
switch:
  - platform: gpio
    # Switch for PMS5003 sensor
    pin: 
      number: D7
    id: pms_set
    name: "Airgradient PMS5003 Switch"
    
light:
  - platform: neopixelbus
    type: GRB
    variant: WS2812x
    pin: GPIO15
    num_leds: 1
    name: "AQI Status LED"
    id: status_led

@ Achim Haug @Achim_AirGradient and @Thor Tielemans @ttielemans: thanks for your ideas!

3 Likes
Extending the life span of the PMS5003 sensor
#2

Very nice. I have look into esphome. It looks interesting.

I just completed air gradient #2 and #3. I made a modification to my case and by swapping 1 side panel, the sht31 can be placed outside the case. I will do some testing and upload the modification if it proves beneficial in temperature accuracy. By accident/stupidity I ordered two regular pms5003 and not the ones with build-in temperature and humidity sensor which seem to be much more accurate.

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#3

Awesome work and thank you for sharing. If anyone is interested, I have a few modifications in my version that:

  • Uses English descriptions and Fahrenheit instead of Celsius
  • Turns the PM2.5 sensor on for 30 seconds every 2 minutes using the sleep/wakeup commands suggested here: Extending the life span of the PMS5003 sensor - #5 by AirGradient, rather than requiring an additional pin (it was too late for me)
  • Adjusts the temp down .5 deg to account for the heat from the PM2.5 sensor (perhaps not even necessary with the cycle on/off though?)

Here’s the source code: AirGradient ESPHome with Sleep (extend PM2.5 sensor lifetime) (github.com)

1 Like
#4

I would be interested in that modification as I already have my SHT30 soldered via wires but haven’t ordered an enclosure at a printer service yet.

In this context: Are you planning to release an updated version of the enclosure that has the screws on the backside? Just for the looks of it :wink:

#5

See my original post My own enclosure for the update files. The screws on the bottom is on the todo list but there is not ETA.

#6

Thank you for sharing, there are some cool ideas in your solution!

I have two questions regarding your approach:

  • How exactly does your power solution work? Did you just cut a USB cable open or are you using some kind of adapter that splits a USB cable into 5V/ground?
  • You are using a sliding moving average for the PMS values. According to the PMS datasheet, you should wait 30s after turning on the sensor in order to get stable values. Did you test your approach with different window sizes? I see the possibility that early values after the fan start could maybe reduce the accuracy of your readings.

Update: I’d also be curious about your LED solution. The code shows that you are using a WS2812x. Could you maybe share a photo showing how you mounted the LED and the name of the specific product with us? I like the idea of an AQI LED and checked some of those RGB LEDs. Many of them are designed as surface mounted packages so it would help to know how you solved it.

#7

Hi,

I hereby send you the answers based on your questions:

1 Like