esphome_hx711_smart_scale.yaml

## Node configuration ##

esphome:
  name: smart_scale
  platform: ESP8266
  board: nodemcuv2

globals:
  - id: initial_zero
    type: float
    restore_value: yes
    # NOTE: make sure to align this value to the one used in "calibrate_linear" below!
    initial_value: '-481989'
    
  - id: auto_tare_enabled
    type: bool
    restore_value: yes
    initial_value: 'true'

  - id: auto_tare_difference
    type: float
    restore_value: yes
    initial_value: '0'

wifi:
  fast_connect: True  # needed for hidden SSID
  networks:
    - ssid: 'YourSSID'
      bssid: '00:00:00:00:00:00'
      password: 'YourPassword'
      hidden: true
  #manual_ip:
  #  static_ip: 192.168.5.49
  #  gateway: 192.168.5.1
  #  subnet: 255.255.255.0

api:
  password: "YourApiPassword"

# Enable logging
logger:
  level: ERROR

ota:
  password: 'YourOtaPassword'

status_led:
  pin:
    number: GPIO2
    inverted: True

button:

  ## Button used to initiate a manual tare
  - platform: template
    id: "${sensor_name}_manual_tare_action_switch"
    name: "${friendly_name} Manual Tare Action"
    icon: mdi:scale-balance
    on_press:
      - lambda: |-
          id(auto_tare_difference) = id(initial_zero) - id(smart_scale_hx711_value_raw).state;

switch:
  ## Switch to enable/disable the auto tare feature
  - platform: template
    id: "${sensor_name}_smart_scale_continuous_tare_enabled"
    name: "${friendly_name} Continuous Tare Enabled"
    lambda: |-
      return id(auto_tare_enabled);
    turn_on_action:
      - lambda: |-
          id(auto_tare_enabled) = true;
    turn_off_action:
      - lambda: |-
          id(auto_tare_enabled) = false;

## Sensor Configuration ##
sensor:
  # template sensors from global variables
  - platform: template
    id: "${sensor_name}_smart_scale_initial_zero"
    name: "${friendly_name} Initial Zero"
    lambda: |-
      return id(initial_zero);
    update_interval: 1s
    
  - platform: template
    id: "${sensor_name}_smart_scale_auto_tare_difference"
    name: "${friendly_name} Auto Tare Difference"
    lambda: |-
      return id(auto_tare_difference);
    update_interval: 1s
    
  # sensors imported from home assistant
  - platform: homeassistant
    id: homeassistant_initial_zero
    entity_id: "input_number.${sensor_name}_initial_zero"
    on_value:
      then:
        - lambda: |-
            id(initial_zero) = x;
  
  # RAW Scale input
  - platform: hx711
    id: "${sensor_name}_hx711_value_raw" 
    internal: True
    dout_pin: GPIO16 #pin D0 on the WEMOS device
    clk_pin: GPIO5 #pin D1 on the WEMOS device
    gain: 128
    update_interval: 0.2s
    filters:
      - quantile:
          window_size: 10
          send_every: 1
          send_first_at: 1
          quantile: .9
    on_value:
      then:
        - sensor.template.publish:
            id: "${sensor_name}_hx711_value" 
            state: !lambda 'return id("${sensor_name}_hx711_value_raw").state;'
        - if:
            condition:
              and:
                - lambda: 'return id(auto_tare_enabled);'
                # current smart scale value is below approx. 10KG (raw value -275743) aka nobody is standing on the scale
                - lambda: 'return id("${sensor_name}_hx711_value").state < 10.0;'
            then:
              - if:
                  condition:
                    # current raw scale value is below expected zero value
                    - lambda: 'return id("${sensor_name}_hx711_value_raw").state < (id(initial_zero) - id(auto_tare_difference));'
                  then:
                    # INcrease Auto-Tare offset to slowly align real zero value with expected zero value
                    - lambda: |-
                        id(auto_tare_difference) += 10;
                  else:
                    # DEcrease Auto-Tare offset to slowly align real zero value with expected zero value
                    - lambda: |-
                        id(auto_tare_difference) -= 10;

    
  # Mapped value to KG
  - platform: template
    id: "${sensor_name}_hx711_value"
    name: "${friendly_name} HX711 Value"
    internal: False
    filters:
      # apply auto_tare difference
      - lambda: 'return x + id(auto_tare_difference);'
      # apply rough calibration
      - calibrate_linear:
          # retrieve these values by evaluating the raw values with loads of known mass.
          # note that a bigger difference between measurements usually results in higher resolution,
          # so measure 0 Kg and the highest known mass you have (like f.ex. your own weight, measured by a normal scale with good accuracy)
          - -481989 -> 0
          - 1339163 -> 88.3
      # map values below 0.1 to 0 (to decrease value changes due to random fluctuation)
      - lambda: |-
          if (x <= 0.1) {
            return 0.0;
          } else {
            return x;
          }
          
    unit_of_measurement: kg
    accuracy_decimals: 2
    # the sensor will automatically update through the 'sensor.template.publish' call
    update_interval: never