Chapter 4 · Connect to Home Assistant 5 min

Show a Sensor

Display a Home Assistant sensor (e.g. living room temperature) on an LVGL label.

The pattern - same for every sensor

homeassistant sensor

on_value

fires on every update

lvgl.label.update

push value to widget

Design a label in the LVGL designer

Place a Label widget on your canvas. This is where the sensor value will appear. Set some placeholder text like --.- °C so you can see it during design.

LVGL Designer with a label widget on the canvas, showing placeholder text

The designer gives every widget an id: automatically (like lv_label_3). You'll use this ID in step 3 to tell ESPHome which widget to update. You can rename it to something meaningful like temp_lbl in the properties panel.

Export the YAML and paste it into your config (same as Chapter 3). The key part is the id::

yamlYour label widget (from the designer)

# Your LVGL widgets (from the designer or hand-written)
# The important thing: each widget needs an id:

lvgl:
  pages:
    - id: main_page
      bg_color: 0xFFFFFF
      pad_all: 0
      widgets:
        - label:
            id: temp_lbl
            x: -35
            y: -20
            align: CENTER
            text: "--.- °C"
            text_color: 0x000000
            text_font: montserrat_28

Find the entity ID in Home Assistant

Every sensor, switch, and light in Home Assistant has a unique entity_id. You need this to tell ESPHome which value to subscribe to.

Method A: Developer Tools

Easiest

In Home Assistant, go to Developer Tools (bottom of the sidebar)
Click the States tab
Type your sensor name in the search box (e.g. "living room temperature")
The Entity column shows the ID: sensor.living_room_temperature

Home Assistant Developer Tools → States with entity filtered

Method B: From any dashboard card

Click any sensor card on your HA dashboard → click the ⚙ gear icon (top right) → the Entity ID is shown near the top. You can copy it directly.

Entity IDs follow this pattern: domain.name

In practice they can be long auto-generated strings like:

sensor.temperature_humidity_sensor_9526_temperature

That's normal - HA auto-generates these from the device name. You can rename them in HA (Settings → Devices → click entity → edit Entity ID) to something friendlier like sensor.living_room_temperature. We'll use the short version in all examples.

Add the sensor block to your YAML

Add this at root level (same indentation as esphome:, wifi:, lvgl:). Replace the entity_id with yours from step 2.

yamlSubscribe to a HA sensor → update label

# Add to your device YAML (root level, same as esphome: / wifi:)

sensor:
  - platform: homeassistant
    id: living_room_temp
    entity_id: sensor.living_room_temperature
    on_value:
      then:
        - lvgl.label.update:
            id: temp_lbl
            text: !lambda |-
              return str_sprintf("%.1f °C", x).c_str();

platform: homeassistantSubscribes to a HA entity via the API

entity_id:Which HA entity to watch

on_value:Fires every time HA sends a new reading

lvgl.label.update:Pushes the value to your LVGL label (matched by id:)

xThe lambda variable holding the sensor's current value

Update multiple widgets from one sensor (label + arc)

Add more actions inside the same on_value:. For example, update a label and an arc at the same time:

yamlLabel + arc from one sensor

# Want to update multiple widgets from one sensor?
# Add more actions inside the same on_value:

sensor:
  - platform: homeassistant
    id: living_room_temp
    entity_id: sensor.living_room_temperature
    on_value:
      then:
        - lvgl.label.update:
            id: temp_lbl
            text: !lambda |-
              return str_sprintf("%.1f °C", x).c_str();
        - lvgl.arc.update:
            id: temp_arc
            value: !lambda 'return (int) x;'

Showing text values (weather, states, names)

For entities that return strings instead of numbers, use text_sensor::

yamlText sensor example

# For text-based entities (weather conditions, states, etc.)
# use text_sensor: instead of sensor:

text_sensor:
  - platform: homeassistant
    id: weather_condition
    entity_id: weather.home
    attribute: condition
    on_value:
      then:
        - lvgl.label.update:
            id: weather_lbl
            text: !lambda 'return x.c_str();'

IDs must match exactly. The id: in lvgl.label.update must be identical to the id: on your LVGL widget - they're case-sensitive. If they don't match, nothing updates and there's no error message.

Flash and see it live

In the ESPHome dashboard: click your device → Install → Wirelessly. Within a second of the sensor changing in HA, your label updates on screen.

Photo of a CYD display showing '22.7 °C' on the label, pulled live from Home Assistant

[I][homeassistant.sensor:015]:

'sensor.living_room_temperature':

State: 22.5

[D][lvgl:034]: label update:

id: temp_lbl → "22.5 °C"

Checkpoint - Does the label update when the sensor value changes in HA?

If yes - you've crossed into live data. The same pattern works for arcs, bars, gauges, anything with an update action.

Yes - keep going Label stays at default value