Temperature Curve

All Revisions

Works with all hardware revisions (Rev 1.0 through Rev 3.3).

Purpose

The Temperature Curve module lets you define a custom 5-point temperature-to-speed curve for granular control over fan behavior. Values between points are linearly interpolated, giving you a smooth speed transition across the entire temperature range.

When to Use

Choose Curve when you need more control points than the linear module’s three zones but don’t need PID’s automatic target-chasing behavior. It’s ideal when you know exactly how you want fans to respond at specific temperatures.

For simpler threshold-based control, see Temperature Linear. For automatic temperature targeting, see Temperature PID. The modules overview has a comparison table.

Works with Stall Guard

This module cooperates with Stall Guard via a safety floor mechanism. If a fan stalls, Stall Guard sets a minimum speed that Temperature Curve will respect during recovery. No extra configuration needed, just include both modules.

Configuration

Variable	Default	Description
friendly_name	"Fancontroller"	Device name prefix for all entities
curve_temp1	"20.0"	Temperature point 1 (C)
curve_speed1	"0.0"	Fan speed at point 1 (%)
curve_temp2	"25.0"	Temperature point 2 (C)
curve_speed2	"25.0"	Fan speed at point 2 (%)
curve_temp3	"30.0"	Temperature point 3 (C)
curve_speed3	"50.0"	Fan speed at point 3 (%)
curve_temp4	"40.0"	Temperature point 4 (C)
curve_speed4	"75.0"	Fan speed at point 4 (%)
curve_temp5	"50.0"	Temperature point 5 (C)
curve_speed5	"100.0"	Fan speed at point 5 (%)
temperature_sensor_id	"fancontroller_temperature"	Id of the sensor supplying the control temperature

How It Works

The five temperature/speed pairs define a piecewise linear curve:

1. Each pair sets a “point” on the curve (e.g., 25 C = 25% speed)
2. Between any two adjacent points, the fan speed is linearly interpolated
3. Below the lowest temperature point, fans run at that point’s speed
4. Above the highest temperature point, fans run at that point’s speed

Auto-sorting: Temperature points are automatically sorted at runtime, so they work even if defined out of order. However, the module validates the curve at boot and logs a warning if points are not monotonically increasing.

Home Assistant Entities

Number Entities

Entity	Range	Step	Unit	Default	Description
Curve Temperature 1	0 — 60	0.5	C	20.0	Temperature point 1
Curve Speed 1	0 — 100	1	%	0	Fan speed at point 1
Curve Temperature 2	0 — 60	0.5	C	25.0	Temperature point 2
Curve Speed 2	0 — 100	1	%	25	Fan speed at point 2
Curve Temperature 3	0 — 60	0.5	C	30.0	Temperature point 3
Curve Speed 3	0 — 100	1	%	50	Fan speed at point 3
Curve Temperature 4	0 — 60	0.5	C	40.0	Temperature point 4
Curve Speed 4	0 — 100	1	%	75	Fan speed at point 4
Curve Temperature 5	0 — 60	0.5	C	50.0	Temperature point 5
Curve Speed 5	0 — 100	1	%	100	Fan speed at point 5

Sensor Entities

Entity	Unit	Description
Curve Output	%	Current interpolated fan speed (updated every 10s)

Switch Entities

Entity	Default	Description
Auto Control Fan 1	ON	Enable curve control for fan 1
Auto Control Fan 2	ON	Enable curve control for fan 2
Auto Control Fan 3	ON	Enable curve control for fan 3
Auto Control Fan 4	ON	Enable curve control for fan 4

Binary Sensor

Entity	Category	Description
Curve Configuration Warning	Diagnostic	ON if temperature points are not monotonically increasing

Web UI grouping

This block goes in your own configuration, not in the module. See why the assignment lives in the consuming config for the reason. version: 3 is what makes entity grouping work at all; without it, entity grouping has no effect.

web_server:
  version: 3
  sorting_groups:
    - id: grp_temp_curve
      name: "Temperature Curve"
      sorting_weight: 110

number:
  - id: !extend curve_temp1
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 10
  - id: !extend curve_speed1
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 20
  - id: !extend curve_temp2
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 30
  - id: !extend curve_speed2
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 40
  - id: !extend curve_temp3
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 50
  - id: !extend curve_speed3
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 60
  - id: !extend curve_temp4
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 70
  - id: !extend curve_speed4
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 80
  - id: !extend curve_temp5
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 90
  - id: !extend curve_speed5
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 100

sensor:
  - id: !extend curve_output_value
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 110

switch:
  - id: !extend auto_control_fan1
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 120
  - id: !extend auto_control_fan2
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 130
  - id: !extend auto_control_fan3
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 140
  - id: !extend auto_control_fan4
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 150

binary_sensor:
  - id: !extend curve_config_warning_sensor
    web_server:
      sorting_group_id: grp_temp_curve
      sorting_weight: 900

YAML Examples

Basic Usage (Default Balanced Curve)

packages:
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          friendly_name: "My Fan Controller"

Silent Profile

Prioritizes low noise. Fans stay off until 25 C and ramp slowly, reaching only 80% at 55 C. Best for quiet home office environments where some temperature rise is acceptable.

packages:
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          friendly_name: "Silent Cooler"
          curve_temp1: "20.0"
          curve_speed1: "0.0"
          curve_temp2: "25.0"
          curve_speed2: "20.0"
          curve_temp3: "35.0"
          curve_speed3: "40.0"
          curve_temp4: "45.0"
          curve_speed4: "60.0"
          curve_temp5: "55.0"
          curve_speed5: "80.0"

Balanced Profile

Good all-around curve that balances noise and cooling. This is the default configuration.

packages:
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          friendly_name: "Balanced Cooler"
          curve_temp1: "20.0"
          curve_speed1: "0.0"
          curve_temp2: "25.0"
          curve_speed2: "25.0"
          curve_temp3: "30.0"
          curve_speed3: "50.0"
          curve_temp4: "40.0"
          curve_speed4: "75.0"
          curve_temp5: "50.0"
          curve_speed5: "100.0"

Aggressive Profile

Reacts quickly to temperature increases with steep ramp. Reaches full speed at 40 C. Best for high-performance setups where cooling takes priority over noise.

packages:
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          friendly_name: "Aggressive Cooler"
          curve_temp1: "20.0"
          curve_speed1: "0.0"
          curve_temp2: "22.0"
          curve_speed2: "30.0"
          curve_temp3: "28.0"
          curve_speed3: "60.0"
          curve_temp4: "35.0"
          curve_speed4: "85.0"
          curve_temp5: "40.0"
          curve_speed5: "100.0"

Server Profile

Always-on baseline cooling with rapid ramp. Fans never fully stop (20% minimum at 15 C), reaching full speed at just 35 C. Designed for server racks and network closets.

packages:
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          friendly_name: "Server Rack"
          curve_temp1: "15.0"
          curve_speed1: "20.0"
          curve_temp2: "20.0"
          curve_speed2: "30.0"
          curve_temp3: "25.0"
          curve_speed3: "50.0"
          curve_temp4: "30.0"
          curve_speed4: "75.0"
          curve_temp5: "35.0"
          curve_speed5: "100.0"

Tuning Tips

Use the HA Number Entities

All 10 curve parameters can be adjusted live from Home Assistant without reflashing. Experiment with different values and watch the Curve Output sensor to see the effect in real time.

• Watch the Configuration Warning sensor — if it shows ON in Home Assistant, your temperature points are not in ascending order. The module still works (points are auto-sorted at runtime), but it’s best practice to define them in order for clarity.
• Define temperatures in ascending order — while auto-sorting handles out-of-order points, having them in order makes your configuration easier to read and debug.
• Start with the Balanced preset — the default curve works well for most scenarios. Adjust individual points based on your environment.
• Consider your fans’ minimum speed — if your fans need at least 20% PWM to spin reliably, make sure your lowest non-zero speed point is at or above that threshold.
• Use the Curve Output sensor for debugging — it updates every 10 seconds and shows the current interpolated fan speed, making it easy to verify your curve behaves as expected at different temperatures.

Controlling From a Different Sensor

By default the module reads fancontroller_temperature, the onboard HDC1080 that every hardware package declares. Set temperature_sensor_id to the id of any other temperature sensor in your configuration to control from that instead:

packages:
  # modules/bme680.yaml is not standalone - it needs the shared I2C bus (bus_a)
  # that your hardware package declares. Use your own board revision here.
  hardware:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files: [hardware-rev-3.1.yaml]
  bme680:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files: [modules/bme680.yaml]
  temperature_curve:
    url: https://github.com/zeroflow/wifi-fancontroller
    ref: main
    files:
      - path: modules/temperature_curve.yaml
        vars:
          temperature_sensor_id: "bme680_temperature"

Omit the variable and it falls back to fancontroller_temperature, so existing configurations keep working unchanged. A misspelled id fails the build rather than quietly falling back to the onboard sensor.

The Qwiic modules build their sensor ids from an id-prefix substitution, so BME680 gives you bme680_temperature, SCD41 gives scd41_temperature, and DS2484 gives whatever ids you assign your own dallas_temp sensors.

If you also run the SSD1306 OLED module, note that it displays the onboard sensor regardless of this setting, so the screen and the fan control can show different temperatures.

The module names the sensor it is reading in its boot log, so you can confirm from a log dump that the override took effect.

External sensors and startup

A sensor that needs time before its first reading — an SCD41 warming up, a BME680 on a long update interval, a Dallas probe — reports no value for a while after boot. During that window this module commands the fans off. Keep the sensor’s update_interval short if that matters to you, and expect the fans not to spin until the first reading lands. The onboard HDC1080 polls every 10 seconds and needs no warm-up, so the window is normally too short to notice; modules/bme680.yaml defaults to a 60 second interval, which stretches it considerably.