esphome-co2-sensor-mhz19.yaml

esphome:
  name: "air-quality-indoor"
  platform: ESP32
  board: "featheresp32"

wifi:
  ssid: "YOUR WIFI NETWORK NAME"
  password: "YOUR WIFI PASSWORD" 

logger:

# Enable Home Assistant API
api:
  password: "A PASSWORD FOR HOME ASSISTANT"

ota:
  password: "A PASSWORD FOR OTA UPDATES"

# CO2 sensor
uart:
  rx_pin: 27
  tx_pin: 26
  baud_rate: 9600

# Dipslay driver: ST7789
spi:
  clk_pin: GPIO18
  mosi_pin: GPIO19

font:
  - file: "Oswald-Light.ttf"
    id: font_70
    size: 70
    glyphs: 0123456789 # Only used for CO2 level

  - file: "Oswald-Light.ttf"
    id: font_30
    size: 30

color:
  - id: color_black
    red: 0%
    green: 0%
    blue: 0%
    white: 0%
  - id: color_green
    red: 0%
    green: 100%
    blue: 0%
  - id: color_yellow
    red: 100%
    green: 100%
    blue: 0%
  - id: color_orange
    red: 100%
    green: 55%
    blue: 0%
  - id: color_red
    red: 100%
    green: 0%
  - id: color_white
    red: 100%
    green: 100%
    blue: 100%

display:
  - platform: st7789v
    id: my_display
    backlight_pin: GPIO4
    cs_pin: GPIO5
    dc_pin: GPIO16
    reset_pin: GPIO23
    brightness: 100%
    rotation: 90
    pages:
      # Page 1: Current CO2 levels
      #    0    - 1000 -> Green
      #    1000 - 1600 -> Yellow
      #    1600 - 2000 -> Orange
      #    >2000       -> Red
      - id: page1
        lambda: |-
          if(!id(co2_sensor).has_state() ){
            it.print(
              it.get_width()/2,
              it.get_height()/2,
              id(font_70),
              color_white,
              TextAlign::CENTER,
              "Starting..."
            );
            return;
          }
         
          auto bg_color = id(color_black);
          auto text_color = id(color_green);
          auto co2 = id(co2_sensor).state;

          if(co2 > 1000) text_color = id(color_yellow);
          if(co2 > 1600) text_color = id(color_orange);
          if(co2 > 2000){
            text_color = id(color_white);
            bg_color = id(color_red);
          }

          it.filled_rectangle(0, 0, it.get_width(), it.get_height(), bg_color);
          it.printf(
            it.get_width()/2, 
            it.get_height()/2, 
            id(font_70), 
            text_color, 
            TextAlign::CENTER, 
            "%.0f",
            co2
          );

      # Page 2: WiFi information
      - id: page2
        lambda: |-
          it.print(
            0, 0,
            id(font_30),
            id(color_white),
            "WiFi details"
          );

          it.printf(
            0, 30,
            id(font_30),
            id(color_white),
            "%s",
            id(wifi_ssid).state.c_str()
          );

          it.printf(
            0, 60,
            id(font_30),
            id(color_white),
            "%s",
            id(wifi_ip_addr).state.c_str()
          );

switch:
  - platform: gpio
    pin: GPIO4
    id: backlight
    internal: true

sensor:
  - platform: mhz19
    co2:
      name: "CO2 Indoor"
      id: "co2_sensor"
    temperature:
      name: "Temperature"
      internal: true
    update_interval: 60s
    automatic_baseline_calibration: false

text_sensor:
  - platform: wifi_info
    ip_address:
      internal: true
      id: wifi_ip_addr
    ssid:
      internal: true
      id: wifi_ssid

binary_sensor:
  # Button to cycle through pages on the display
  - platform: gpio
    pin:
      number: GPIO35
      inverted: true
    id: button_1
    on_click:
      then:
        - display.page.show_next: my_display
        - component.update: my_display

  # Button to toggle the backlight (for use at night)
  - platform: gpio
    pin:
      number: GPIO0
      inverted: true
    id: button_2
    on_click:
      then:
        - switch.toggle: backlight 

According to https://esphome.io/components/sensor/dht.html
It should be as simple as:

sensor:
  - platform: dht
    pin: PIN_NUMBER_HERE
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"

Just make sure to add the correct pin number.

Hello @Savjee.
Can you help me with the yml file? How to add a relay switching in 1000ppm for 60 seconds? on which pin, the best?
Thank you.