Press to Check Climate¶

Want a quick read on how the room feels without opening Home Assistant? Press the button and the Onboard RGB LED gives you one color for the current temperature, then another for the current humidity.

The Onboard RGB LED on the ESP32-C6 is all you need for this tutorial, so the LED & Buzzer module can sit this one out.

Before you start

Work through these pages first. This tutorial assumes your device is flashed and all three components are connected:

First Steps to create your starter kit device and add the Onboard RGB LED component.
Adding the Button Module to wire up the input.
Adding the Temperature and Humidity Module to wire up the sensor.

Build the automation¶

This tutorial has two versions of the same automation. Both end with the same button-press readout. Pick the tab below.

Beginner uses hardcoded thresholds (18 °C and 24 °C for temperature, 30% and 60% for humidity) and Device Builder's Sensor → In Range condition. No lambda, no extra components.
Advanced adds four user-editable threshold number entities plus a °C / °F select, with lambda conditions that convert at compare time. Tune from the web server or Home Assistant any time, no re-flash.

Color bands¶

Temperature band	Color	Humidity band	Color
Below 18 °C (64 °F)	Blue	Below 30%	Orange
18 °C to 24 °C (64 °F to 75 °F)	Green	30% to 60%	Green
Above 24 °C (75 °F)	Red	Above 60%	Blue

BeginnerAdvanced

Hardcoded thresholds, no extra components.

The GUI fields take Celsius numbers

The AHT20 sensor publishes its readings in Celsius, so the Above and Below values you enter for the temperature If conditions need to be Celsius numbers. The Fahrenheit equivalents in the table above are for reference only.

A single Button → On Click automation whose action body chains nine steps: three If conditions for temperature, a delay and clear, another delay, three If conditions for humidity, a final delay and clear.

Open your starter kit device in ESPHome Device Builder and click Edit. If you need a refresher on the editor, see the Device Builder Tour.
In the editor's left pane, expand the Automations dropdown and click Add Automation.
Set up the trigger:
- What should this automation react to? → A configured component
- Which configured component? → Button Module (binary_sensor.gpio)
- Which trigger? → Binary Sensor → On Click
Click Continue. You land on the Binary Sensor → On Click editor with the Target already set to your Button module.

Show the temperature band¶

Three If actions, one per band. Each If checks whether the temperature is inside its band and, if so, turns the LED to that band's color.

Under Actions, click + Add action and choose Control flow → If.
On the new If action, set the Condition:
- Condition type → Sensor → In Range
- ID → Temperature
- Below → 18.0 (leave Above blank)
Under the If's Then branch, click + Add action and pick Light → Turn On:
- ID → Onboard RGB LED
- Brightness 100% (1)
- Red 0%, Green 0%, Blue 100%
1. Setting Brightness explicitly on every Light → Turn On keeps the colors at full output. If you leave it off and someone dims the LED from the web server or Home Assistant beforehand, your "red" comes back muted at whatever brightness was last set.
Add a second If for the comfortable band. Condition: Above 18.0, Below 24.0. Color: green (Red 0%, Green 100%, Blue 0%).
Show the click-by-click
1. Under Actions, click + Add action and choose Control flow → If.
2. Set the Condition:
  - Condition type → Sensor → In Range
  - ID → Temperature
  - Above → 18.0
  - Below → 24.0
3. Under the If's Then branch, click + Add action and pick Light → Turn On:
  - ID → Onboard RGB LED
  - Brightness 100%
  - Red 0%, Green 100%, Blue 0%
Add a third If for the hot band. Condition: Above 24.0 (leave Below blank). Color: red (Red 100%, Green 0%, Blue 0%).
Show the click-by-click
1. Under Actions, click + Add action and choose Control flow → If.
2. Set the Condition:
  - Condition type → Sensor → In Range
  - ID → Temperature
  - Above → 24.0 (leave Below blank)
3. Under the If's Then branch, click + Add action and pick Light → Turn On:
  - ID → Onboard RGB LED
  - Brightness 100%
  - Red 100%, Green 0%, Blue 0%

Pause, then clear the LED¶

After the three If actions, the LED is showing the temperature band's color. Hold it for 3 seconds, then turn it off for 1 second before showing humidity.

Add a Control flow → Delay of 3s.
Add Light → Turn Off on Onboard RGB LED.
Add a Control flow → Delay of 1s. This gap is what tells the viewer the next color is humidity, not temperature.

Show the humidity band¶

Same shape as the temperature section, three If actions with Sensor → In Range conditions on Humidity.

Add an If with condition Sensor → In Range, ID Humidity, Below 30.0. Action: Light → Turn On with Brightness 100%, Red 100%, Green 50%, Blue 0% (orange).
Add a second If: Above 30.0, Below 60.0. Action: Brightness 100%, Red 0%, Green 100%, Blue 0% (green).
Add a third If: Above 60.0. Action: Brightness 100%, Red 0%, Green 0%, Blue 100% (blue).

Hold, then clear¶

Add a Control flow → Delay of 3s.
Add a final Light → Turn Off, ID → Onboard RGB LED.

What the GUI built in YAML

Your button section now has a single on_click trigger that runs the full sequence:

binary_sensor:
  - platform: gpio
    name: Button Module
    pin:
      inverted: true
      mode:
        input: true
        pullup: true
      number: 6
    id: button_module
    on_click:
      then:
        - if:
            condition:
              sensor.in_range:
                id: aht_temperature
                below: 18.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 0%
                  blue: 100%
        - if:
            condition:
              sensor.in_range:
                id: aht_temperature
                above: 18.0
                below: 24.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 100%
                  blue: 0%
        - if:
            condition:
              sensor.in_range:
                id: aht_temperature
                above: 24.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 100%
                  green: 0%
                  blue: 0%
        - delay: 3s
        - light.turn_off: onboard_rgb_led
        - delay: 1s
        - if:
            condition:
              sensor.in_range:
                id: aht_humidity
                below: 30.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 100%
                  green: 50%
                  blue: 0%
        - if:
            condition:
              sensor.in_range:
                id: aht_humidity
                above: 30.0
                below: 60.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 100%
                  blue: 0%
        - if:
            condition:
              sensor.in_range:
                id: aht_humidity
                above: 60.0
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 0%
                  blue: 100%
        - delay: 3s
        - light.turn_off: onboard_rgb_led

Same on-press sequence, but the four band thresholds live in editable number components and a select lets you switch between °C and °F. Tune from the web server or Home Assistant any time, no re-flash.

Add the tunable components¶

Before the automation can compare against editable thresholds, the device needs five new components: two number entities for temperature bounds, two for humidity bounds, and one select to pick the temperature unit.

Temperature threshold numbers

In Device Builder, click Edit on your starter kit device.
Scroll to Components and click + Add Component.
Search for Template Number and click Add.
Fill in the form:
- Name → Cold threshold
- ID → temp_min
- Initial value → 18
- Min value → -50
- Max value → 200
- Step → 0.5
- Mode → Box
- Optimistic → on
- Restore value → on (1)
1. Restore value persists the user's last value to flash so a reboot doesn't reset the threshold to its initial_value.
Click Add again and repeat for the hot threshold: Name Hot threshold, ID temp_max, Initial value 24, same min/max/step/mode/optimistic/restore settings.

Humidity threshold numbers

Add two more template numbers with humidity-appropriate bounds.

Name Dry threshold, ID humidity_min, Initial value 30, Min value 0, Max value 100, Step 1, Mode Box, Optimistic on, Restore value on.
Name Humid threshold, ID humidity_max, Initial value 60, same min/max/step/mode/optimistic/restore.

Temperature unit select

Click + Add Component, search for Template Select, and click Add.
Fill in the form:
- Name → Temperature unit
- ID → temp_unit
- Options → °C and °F (one per line)
- Initial option → °C
- Optimistic → on
- Restore value → on
Click Add.

What the GUI built in YAML (components)

number:
  - platform: template
    name: "Cold threshold"
    id: temp_min
    initial_value: 18
    min_value: -50
    max_value: 200
    step: 0.5
    mode: box
    optimistic: true
    restore_value: true
  - platform: template
    name: "Hot threshold"
    id: temp_max
    initial_value: 24
    min_value: -50
    max_value: 200
    step: 0.5
    mode: box
    optimistic: true
    restore_value: true
  - platform: template
    name: "Dry threshold"
    id: humidity_min
    initial_value: 30
    min_value: 0
    max_value: 100
    step: 1
    mode: box
    optimistic: true
    restore_value: true
  - platform: template
    name: "Humid threshold"
    id: humidity_max
    initial_value: 60
    min_value: 0
    max_value: 100
    step: 1
    mode: box
    optimistic: true
    restore_value: true

select:
  - platform: template
    name: "Temperature unit"
    id: temp_unit
    options:
      - "°C"
      - "°F"
    initial_option: "°C"
    optimistic: true
    restore_value: true

Build the action sequence¶

Same single Button → On Click automation as the Beginner version, but each If uses a Lambda condition that reads the user's threshold from a number entity, converts to °C if the select says °F, and compares against the raw sensor value.

ESPHome ships unit-conversion helpers

Lambdas can call fahrenheit_to_celsius(value) and celsius_to_fahrenheit(value) directly (defined in esphome/core/helpers.h). No #include, no math by hand.

The °F in your lambda must match the °F in your select

The lambda comparisons below check id(temp_unit).state == "°F". That string comparison is byte-exact. If the ° character in your select options came from a different keyboard layout than the one in the lambda (some layouts produce U+00B0 DEGREE SIGN, others produce U+02DA RING ABOVE, which looks identical), the comparison silently always returns false and °F mode never triggers. Copy-paste the ° from one place to the other to be safe, or change the select options and the lambda comparisons to plain "C" / "F".

Expand the Automations dropdown, click Add Automation.
Set up the trigger:
- What should this automation react to? → A configured component
- Which configured component? → Button Module (binary_sensor.gpio)
- Which trigger? → Binary Sensor → On Click
Click Continue.

Show the temperature band

Three If actions with Lambda conditions, one per band.

Under Actions, click + Add action and choose Control flow → If.

Set the Condition:

Condition type → Lambda
Paste in the body below.

float t = id(temp_min).state;
if (id(temp_unit).state == "°F") t = fahrenheit_to_celsius(t);
return id(aht_temperature).state < t;

Under the If's Then branch, click + Add action and pick Light → Turn On:
- ID → Onboard RGB LED
- Brightness 100%
- Red 0%, Green 0%, Blue 100%

Add a second If. Lambda condition body:

bool is_f = id(temp_unit).state == "°F";
float tmin = is_f ? fahrenheit_to_celsius(id(temp_min).state) : id(temp_min).state;
float tmax = is_f ? fahrenheit_to_celsius(id(temp_max).state) : id(temp_max).state;
float t = id(aht_temperature).state;
return t >= tmin && t <= tmax;

Then → Light → Turn On Onboard RGB LED with Brightness 100%, Red 0%, Green 100%, Blue 0%.

Add a third If. Lambda condition body:

float t = id(temp_max).state;
if (id(temp_unit).state == "°F") t = fahrenheit_to_celsius(t);
return id(aht_temperature).state > t;

Then → Light → Turn On Onboard RGB LED with Brightness 100%, Red 100%, Green 0%, Blue 0%.

Pause, then clear the LED

Add a Control flow → Delay of 3s.
Add Light → Turn Off on Onboard RGB LED.
Add a Control flow → Delay of 1s.

Show the humidity band

Three more If actions with lambda conditions. No unit conversion needed (humidity is always a percent).

Lambda condition:
```
return id(aht_humidity).state < id(humidity_min).state;
```
Then → Light → Turn On Onboard RGB LED with Brightness 100%, Red 100%, Green 50%, Blue 0% (orange).

Second If:

float h = id(aht_humidity).state;
return h >= id(humidity_min).state && h <= id(humidity_max).state;

Then → Light → Turn On with Brightness 100%, Red 0%, Green 100%, Blue 0% (green).

Third If:
```
return id(aht_humidity).state > id(humidity_max).state;
```
Then → Light → Turn On with Brightness 100%, Red 0%, Green 0%, Blue 100% (blue).

Hold, then clear

Add a Control flow → Delay of 3s.
Add a final Light → Turn Off, ID → Onboard RGB LED.

What the GUI built in YAML

binary_sensor:
  - platform: gpio
    name: Button Module
    pin:
      inverted: true
      mode:
        input: true
        pullup: true
      number: 6
    id: button_module
    on_click:
      then:
        - if:
            condition:
              lambda: |-
                float t = id(temp_min).state;
                if (id(temp_unit).state == "°F") t = fahrenheit_to_celsius(t);
                return id(aht_temperature).state < t;
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 0%
                  blue: 100%
        - if:
            condition:
              lambda: |-
                bool is_f = id(temp_unit).state == "°F";
                float tmin = is_f ? fahrenheit_to_celsius(id(temp_min).state) : id(temp_min).state;
                float tmax = is_f ? fahrenheit_to_celsius(id(temp_max).state) : id(temp_max).state;
                float t = id(aht_temperature).state;
                return t >= tmin && t <= tmax;
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 100%
                  blue: 0%
        - if:
            condition:
              lambda: |-
                float t = id(temp_max).state;
                if (id(temp_unit).state == "°F") t = fahrenheit_to_celsius(t);
                return id(aht_temperature).state > t;
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 100%
                  green: 0%
                  blue: 0%
        - delay: 3s
        - light.turn_off: onboard_rgb_led
        - delay: 1s
        - if:
            condition:
              lambda: 'return id(aht_humidity).state < id(humidity_min).state;'
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 100%
                  green: 50%
                  blue: 0%
        - if:
            condition:
              lambda: |-
                float h = id(aht_humidity).state;
                return h >= id(humidity_min).state && h <= id(humidity_max).state;
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 100%
                  blue: 0%
        - if:
            condition:
              lambda: 'return id(aht_humidity).state > id(humidity_max).state;'
            then:
              - light.turn_on:
                  id: onboard_rgb_led
                  brightness: 100%
                  red: 0%
                  green: 0%
                  blue: 100%
        - delay: 3s
        - light.turn_off: onboard_rgb_led

Tune your thresholds without re-flashing¶

After Install, the four threshold numbers and the unit select live in the web server and Home Assistant. Change any of them from a browser and the next button press uses the new values immediately. No recompile required.

Changing the unit doesn't auto-convert your stored values

If you switch Temperature unit from °C to °F after entering thresholds, the stored numbers stay the same: 18 was 18 °C, now it's interpreted as 18 °F (which is about −7.8 °C). The simplest fix is to set the unit first, then enter your thresholds in that unit. For an automatic conversion when the select changes, see the optional section below.

Optional: auto-convert thresholds when the unit changes¶

Add an on_value action to the Temperature unit select so that switching °C ↔ °F rewrites both temperature threshold numbers to the equivalent value in the new unit. This is a YAML-only edit because tracking the previous select value needs a globals: block.

In the YAML pane, add a globals: section that records the last unit:

globals:
  - id: prev_temp_unit
    type: std::string
    restore_value: true
    initial_value: '"°C"'

Under your Temperature unit select, add an on_value block:

select:
  - platform: template
    name: "Temperature unit"
    id: temp_unit
    options:
      - "°C"
      - "°F"
    initial_option: "°C"
    optimistic: true
    restore_value: true
    on_value:
      - then:
          - if:
              condition:
                lambda: 'return id(prev_temp_unit) == "°C" && x == "°F";'
              then:
                - number.set:
                    id: temp_min
                    value: !lambda 'return celsius_to_fahrenheit(id(temp_min).state);'
                - number.set:
                    id: temp_max
                    value: !lambda 'return celsius_to_fahrenheit(id(temp_max).state);'
          - if:
              condition:
                lambda: 'return id(prev_temp_unit) == "°F" && x == "°C";'
              then:
                - number.set:
                    id: temp_min
                    value: !lambda 'return fahrenheit_to_celsius(id(temp_min).state);'
                - number.set:
                    id: temp_max
                    value: !lambda 'return fahrenheit_to_celsius(id(temp_max).state);'
          - lambda: 'id(prev_temp_unit) = x;'

Save and install. Flip the unit select once each direction to verify the numbers convert as you'd expect.

Install the firmware¶

Your automation is saved in Device Builder, but the device is still running its old firmware. Compile and install the new code to push the change.

Click Save in the bottom right of the editor.
Click Install, then pick On the Network to push the new firmware over Wi-Fi.
Wait for the compile and flash to finish. The device reboots once the install is done.

Test the automation¶

With the device back online, press the button on the Button module. The Onboard RGB LED runs the full sequence in seven seconds: temperature color for 3 s, dark for 1 s, humidity color for 3 s, dark. Press it again any time you want a quick read.

Troubleshooting¶

The colors don't reflect what I just did to the sensor. The temp and humidity sensors publish on a schedule (every 60 seconds by default), so the colors show the most recent reading, not a fresh check at the moment of the press. Lower the sensor's update_interval while testing for snappier feedback.
First press after boot does nothing. Right after boot, the sensor hasn't published a reading yet, so the If comparisons silently come back false and the LED stays as-is. Wait one publish cycle (60 seconds by default) and try again.

Next steps¶

The same trigger / condition / delay / light pattern works with any sensor and any light on your kit. Swap the temperature sensor for a CO2 reading, the button trigger for a motion event, or the Onboard RGB LED for the LED & Buzzer module's rgb_leds strip, and you have a new readout. Then bring it into Home Assistant so you can tune it from anywhere.

Next - Connect to Home Assistant