Thermostat device guide

The Thermostat device type may be implemented using several Home API traits, but the primary trait is Thermostat. Following are the required and optional traits for Thermostat devices.

Home APIs Device Type Traits Sample App Use Case

Thermostat

ThermostatDevice

A device that is capable of having either built-in or separate sensors for temperature, humidity or occupancy, and allows the desired temperature to be set. A Thermostat is capable of sending heating and/or cooling requirement notifications to a heating/cooling unit (for example, an indoor air handler) or is capable of including a mechanism to control a heating or cooling unit directly.

Required Traits
     matter Identify
     matter Thermostat

Optional Traits
     matter Thermostat User Interface Configuration
     google Extended Thermostat
Thermostat

Automation API support

The following Thermostat traits and elements are supported in the Automation API.

Trait Trait type Element type Element
Thermostat matter Command SetpointRaiseLower
Thermostat matter Attribute activePresetHandle
Thermostat matter Attribute localTemperature
Thermostat matter Attribute occupancy
Thermostat matter Attribute occupiedCoolingSetpoint
Thermostat matter Attribute occupiedHeatingSetpoint
Thermostat matter Attribute outdoorTemperature
Thermostat matter Attribute setpointChangeSource
Thermostat matter Attribute systemMode
Thermostat matter Attribute temperatureSetpointHold
Thermostat matter Attribute temperatureSetpointHoldDuration
Thermostat matter Attribute thermostatRunningMode
Thermostat matter Attribute thermostatRunningState
Thermostat matter Attribute unoccupiedCoolingSetpoint
Thermostat matter Attribute unoccupiedHeatingSetpoint
ExtendedThermostat google Attribute activePresetHandle
ExtendedThermostat google Attribute activeRemoteTemperatureSensorIds
ExtendedThermostat google Attribute averageLocalTemperature
ExtendedThermostat google Attribute extendedRunningMode
ExtendedThermostat google Attribute extendedSystemMode
SimplifiedThermostat google Command SetSystemMode
SimplifiedThermostat google Attribute systemMode

Get the ambient temperature

Get the ambient temperature using Thermostat

To get the thermostat's ambient temperature using the Thermostat trait, read the localTemperature attribute.

Device API

// Get the ambient temperature
val thermostat = home.devices().list().first { device -> device.has(Thermostat) }

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat
    .type(ThermostatDevice)
    .mapNotNull { it.standardTraits.thermostat }
    .distinctUntilChanged()

val localTempFlow = thermostatTraitFlow.mapNotNull { it?.localTemperature }

Automation API

val automation = automation {
  sequential {
    val starterNode = starter<_>(thermostat, ThermostatDevice, Thermostat)

    // If the temperature is higher than 35C...
    condition { expression = starterNode.localTemperature greaterThan 35 }

    // ...and the automation hasn't been run for at least an hour...
    suppressFor(Duration.ofHours(1))

    // ...broadcast a message
    action(speaker, SpeakerDevice) {
      command(AssistantBroadcast.broadcast("It's very hot outside."))
    }
  }
}

Get the ambient temperature using TemperatureMeasurement

To get the thermostat's ambient temperature using the TemperatureMeasurement trait, read the measuredValue attribute.

Device API

val temperatureTraitFlow: Flow<TemperatureMeasurement?> =
  thermostat
    .type(TemperatureSensorDevice)
    .map { it.standardTraits.temperatureMeasurement }
    .distinctUntilChanged()

val localTemp: Short? = temperatureTraitFlow.first()?.measuredValue

Automation API

val automation = automation {
  sequential {
    val temperature = starter<_>(thermostat, ThermostatDevice, TemperatureMeasurement)
    val stateReaderNode = stateReader<_>(light, DimmableLightDevice, OnOff)
    condition() {
      val expr1 = temperature.measuredValue greaterThanOrEquals 35
      val expr2 = stateReaderNode.onOff equals true
      expression = expr1 and expr2
    }
    action(light, DimmableLightDevice) { command(OnOff.on()) }
  }
}

Get the average temperature using ExtendedThermostat

To get the average temperature across multiple sensors, read the ExtendedThermostat trait's averageLocalTemperature attribute.

Device API

// Get the average temperature
val thermostat = home.devices().list().first { device -> device.has(TemperatureSensorDevice) }

val temperatureTraitFlow: Flow<TemperatureMeasurement?> =
  thermostat
    .type(TemperatureSensorDevice)
    .map { it.standardTraits.temperatureMeasurement }
    .distinctUntilChanged()

val localTemp: Short? = temperatureTraitFlow.first()?.measuredValue

Automation API

val automation = automation {
  sequential {
    val temperature = starter<_>(thermostat, ThermostatDevice, ExtendedThermostat)
    val stateReaderNode = stateReader<_>(light, DimmableLightDevice, OnOff)
    //  if the average temperature is >= 35C
    condition() {
      val expr1 = temperature.averageLocalTemperature greaterThanOrEquals 35
      val expr2 = stateReaderNode.onOff equals true
      expression = expr1 and expr2
    }
    // Turn on the light
    action(light, DimmableLightDevice) { command(OnOff.on()) }
  }
}

Get the ambient humidity

To get the thermostat's ambient humidity using the RelativeHumidityMeasurement trait, read the measuredValue attribute.

Device API

// Get the ambient humidity

val humidityTraitFlow: Flow<RelativeHumidityMeasurement?> =
  humiditySensingThermostat
    .type(HumiditySensorDevice)
    .map { it.standardTraits.relativeHumidityMeasurement }
    .distinctUntilChanged()

val localHumidity: UShort? = humidityTraitFlow.first()?.measuredValue

Automation API

val automation = automation {
  sequential {
    val humidity = starter<_>(thermostat, HumiditySensorDevice, RelativeHumidityMeasurement)
    val stateReaderNode = stateReader<_>(light, DimmableLightDevice, OnOff)
    // if the ambient humidity is >= 80%
    condition() {
      val expr1 = (humidity.measuredValue greaterThanOrEquals 80u)
      val expr2 = (stateReaderNode.onOff equals true)
      expression = expr1 and expr2
    }
    // Turn on the light
    action(light, DimmableLightDevice) { command(OnOff.on()) }
  }
}

Select the displayed temperature scale

To change the temperature unit of measurement that's used for the thermostat display, set the ThermostatUserInterfaceConfigurationTrait's temperatureDisplayMode attribute to either TemperatureDisplayModeEnum.Celsius or TemperatureDisplayModeEnum.Fahrenheit.

Device API

// Set the displayed temperature scale to Fahrenheit
val uiConfig =
  home
    .devices()
    .list()
    .filter { device -> device.has(ThermostatUserInterfaceConfiguration) }
    .first()

val uiConfigTraitFlow: Flow<ThermostatUserInterfaceConfiguration?> =
  uiConfig
    .type(ThermostatDevice)
    .map { it.standardTraits.thermostatUserInterfaceConfiguration }
    .distinctUntilChanged()

val uiConfigTrait: ThermostatUserInterfaceConfiguration = uiConfigTraitFlow.first()!!

if (
  uiConfigTrait.supports(ThermostatUserInterfaceConfiguration.Attribute.temperatureDisplayMode)
) {
  val unused =
    uiConfigTrait.update { setTemperatureDisplayMode(TemperatureDisplayModeEnum.Fahrenheit) }
}

Automation API

val automation = automation {
  isActive = true
  sequential {
    val stateReaderNode =
      stateReader<_>(thermostat, ThermostatDevice, ThermostatUserInterfaceConfiguration)

    // When someone says "Show the temperature in Fahrenheit",
    val unused =
      starter<_>(structure, VoiceStarter.OkGoogleEvent) {
        parameter(VoiceStarter.OkGoogleEvent.query("Show the temperature in Fahrenheit"))
      }
    // if the temperature isn't being shown in Fahrenheit
    condition() {
      expression =
        stateReaderNode.temperatureDisplayMode notEquals TemperatureDisplayModeEnum.Fahrenheit
    }
    // display the current temperature using Fahrenheit
    action(thermostat, ThermostatDevice) {
      update(ThermostatUserInterfaceConfiguration) {
        setTemperatureDisplayMode(TemperatureDisplayModeEnum.Fahrenheit)
      }
    }
  }
}

Change the operating mode

The Thermostat can be limited to certain operating modes, defined by ThermostatTrait.SystemModeEnum, by setting the ThermostatTrait.Attributes.systemMode attribute, whose values are defined by ThermostatTrait.Attributes.SystemModeEnum.

Device API

val thermostatDevice = structure.devices().list().first { device -> device.has(Thermostat) }

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!

// Set the system mode to Auto
if (thermostatTrait.supports(Thermostat.Attribute.systemMode)) {
  val unused = thermostatTrait.update { setSystemMode(SystemModeEnum.Auto) }
}

Automation API

val automation = automation {
  isActive = true
  // When the door lock state changes
  sequential {
    val doorLockEvent = starter<_>(doorLock, DoorLockDevice, LockOperationEvent)
    val stateReaderNode = stateReader<_>(thermostat, ThermostatDevice, SimplifiedThermostat)

    // if the door is unlocked and the thermostat is in Eco mode
    condition() {
      val expr1 = (doorLockEvent.lockOperationType equals LockOperationTypeEnum.Unlock)
      val expr2 = (stateReaderNode.systemMode equals SimplifiedThermostatSystemModeEnum.Eco)
      expression = expr1 and expr2
    }

    // Set the thermostat to Auto mode
    action(thermostat, ThermostatDevice) {
      command(SimplifiedThermostat.setSystemMode(SimplifiedThermostatSystemModeEnum.Auto))
    }
  }
}

When the thermostat is set to SystemModeEnum.Auto, additional information about the running mode of the thermostat can be read from ThermostatTrait.Attributes.thermostatRunningMode which is populated with values from ThermostatRunningModeEnum.

Device API

// Get the current thermostat running mode

val runningModeTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val runningMode: ThermostatTrait.ThermostatRunningModeEnum? =
  runningModeTraitFlow.first()?.thermostatRunningMode

Automation API

val automation = automation {
  isActive = true
  sequential {
    val stateReaderNode = stateReader<_>(thermostat, ThermostatDevice, Thermostat)
    // at 10:00am
    val unused =
      starter<_>(structure, Time.ScheduledTimeEvent) {
        parameter(Time.ScheduledTimeEvent.clockTime(LocalTime.of(10, 0, 0, 0)))
      }

    // if the thermostat is in Auto mode and is currently cooling
    condition() {
      val expr1 = (stateReaderNode.systemMode equals ThermostatTrait.SystemModeEnum.Auto)
      val expr2 =
        (stateReaderNode.thermostatRunningMode equals
          ThermostatTrait.ThermostatRunningModeEnum.Cool)
      expression = expr1 and expr2
    }
    // announce that it's in Cool mode
    action(structure) {
      command(AssistantBroadcast.broadcast("The thermostat is currently running in Cool mode."))
    }
  }
}

The SimplifiedThermostatTrait is designed to streamline the process of setting the operating mode in automations. To change the thermostat's operating mode using the SimplifiedThermostatTrait, use the SetSystemModeCommand, whose values are defined by SimplifiedThermostatTrait.SystemModeEnum.

This trait is only available for use with the Automation API.

Automation API

val automation = automation {
  isActive = true

  sequential {
    // When the presence state changes...
    val starterNode = starter<_>(structure, AreaPresenceState)
    // ...and if the area is unoccupied...
    condition() {
      expression = starterNode.presenceState equals PresenceState.PresenceStateVacant
    }
    // Set the thermostat to Eco mode
    action(thermostat, ThermostatDevice) {
      command(SimplifiedThermostat.setSystemMode(SimplifiedThermostatSystemModeEnum.Eco))
    }
  }
}

To determine the system modes that a thermostat can operate in, read the ThermostatTrait.Attributes.controlSequenceOfOperation, whose values are determined by the ThermostatTrait.ControlSequenceOfOperationEnum.

Device API

// Get the controlSequenceOfOperation
val standardTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val controlSequenceOfOperation: ThermostatTrait.ControlSequenceOfOperationEnum? =
  standardTraitFlow.first()?.controlSequenceOfOperation

Automation API

val automation = automation {
  isActive = true
  sequential {
    val stateReaderNode = stateReader<_>(thermostat, ThermostatDevice, Thermostat)
    // When someone says "Switch to cool mode",
    val unused =
      starter<_>(structure, VoiceStarter.OkGoogleEvent) {
        parameter(VoiceStarter.OkGoogleEvent.query("Switch to cool mode"))
      }
    // if the thermostat is capable of operating in Cool mode,
    condition() {
      val expr1 =
        stateReaderNode.controlSequenceOfOperation notEquals
          ControlSequenceOfOperationEnum.HeatingOnly
      val expr2 =
        stateReaderNode.controlSequenceOfOperation notEquals
          ControlSequenceOfOperationEnum.HeatingWithReheat
      expression = expr1 and expr2
    }

    action(thermostat, ThermostatDevice) {
      // switch to Cool mode
      update(SimplifiedThermostat) {
        command(SimplifiedThermostat.setSystemMode(SimplifiedThermostatSystemModeEnum.Cool))
      }
    }
  }
}

Change the programming operation mode

The programming operation mode of the thermostat may be changed using the Thermostat's thermostatProgrammingOperationMode, whose values are defined by the ProgrammingOperationModeBitmap.

Device API

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!

if (thermostatTrait.supports(Thermostat.Attribute.thermostatProgrammingOperationMode)) {
  val programmingOperationMode = thermostatTrait.thermostatProgrammingOperationMode!!

  // Enable autoRecovery on the thermostatProgrammingOperationMode
  val unused =
    thermostatTrait.update {
      setThermostatProgrammingOperationMode(
        ThermostatTrait.ProgrammingOperationModeBitmap(
          programmingOperationMode.scheduleActive,
          true,
          programmingOperationMode.economy,
        )
      )
    }
}

Automation API

// When someone says "Reset programming operation mode"
val automation = automation {
  isActive = true
  sequential {
    val unused =
      starter<_>(structure, VoiceStarter.OkGoogleEvent) {
        parameter(VoiceStarter.OkGoogleEvent.query("Reset programming operation mode"))
      }
    // Set all the flags on the programming operation mode
    action(thermostat, ThermostatDevice) {
      update(Thermostat) {
        setThermostatProgrammingOperationMode(ProgrammingOperationModeBitmap(true, true, true))
      }
    }
  }
}

Change the temperature setpoint

To change the temperature setpoint using the Thermostat, call the ThermostatTrait.SetpointRaiseLowerCommand.

Device API

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!

// lower the temperature setpoint by 1 degree C
thermostatTrait.setpointRaiseLower(amount = 1, mode = SetpointRaiseLowerModeEnum.Cool)

Automation API

val automation = automation {
  isActive = true
  sequential {
    val stateReaderNode = stateReader<_>(thermostat, ThermostatDevice, Thermostat)
    // At 10:00pm
    val unused =
      starter<_>(structure, Time.ScheduledTimeEvent) {
        parameter(Time.ScheduledTimeEvent.clockTime(LocalTime.of(22, 0, 0, 0)))
      }
    // if the setpoint is warmer than 19C
    condition() { expression = stateReaderNode.occupiedCoolingSetpoint greaterThan 19 }

    // lower the temperature setpoint by 5 degrees
    action(thermostat, ThermostatDevice) {
      command(Thermostat.setpointRaiseLower(SetpointRaiseLowerModeEnum.Cool, 5))
    }
  }
}

Prioritize a temperature setpoint

You can make a temperature setpoint take precedence over a preprogrammed schedule by setting the ThermostatTrait's temperatureSetpointHold attribute to TemperatureSetpointHoldEnum.SetpointHoldOn, or have the schedule take precedence by setting it to TemperatureSetpointHoldEnum.SetpointHoldOff.

Device API

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!

if (thermostatTrait.supports(Thermostat.Attribute.temperatureSetpointHold)) {
  // Set temperatureSetpointHold to SetpointHoldOn
  // allowing temperature setpoints to override any preprogrammed schedules.

  val unused =
    thermostatTrait.update {
      setTemperatureSetpointHold(TemperatureSetpointHoldEnum.SetpointHoldOn)
    }

Automation API

val automation = automation {
  isActive = true
  sequential {

    // When someone says "Prioritize thermostat setpoint"
    val unused =
      starter<_>(structure, VoiceStarter.OkGoogleEvent) {
        parameter(VoiceStarter.OkGoogleEvent.query("Prioritize thermostat setpoint"))
      }
    // make temperature setpoints override any preprogrammed schedules.
    action(thermostat, ThermostatDevice) {
      val unused2 =
        update(Thermostat) {
          setTemperatureSetpointHold(TemperatureSetpointHoldEnum.SetpointHoldOn)
        }
    }
  }

Set ThermostatTrait.Attributes.temperatureSetpointHoldDuration to control how many minutes a setpoint hold is active.

Device API

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!

if (thermostatTrait.supports(Thermostat.Attribute.temperatureSetpointHoldDuration)) {
  // Set the setpoint hold duration to 60 minutes
  val unused = thermostatTrait.update { setTemperatureSetpointHoldDuration(60u) }
}

Automation API

val automation = automation {
  isActive = true
  sequential {
    val stateReaderNode = stateReader<_>(thermostat, ThermostatDevice, Thermostat)
    val unused = starter<_>(thermostat, ThermostatDevice, Thermostat)

    // if the temperature setpoint hold duration is less than 60 minutes...
    condition() { expression = stateReaderNode.temperatureSetpointHoldDuration.lessThan(60u) }

    // ...and the automation hasn't been run for at least 24 hours...
    suppressFor(Duration.ofHours(24))

    // ...set the temperature setpoint hold duration to 60 minutes
    action(thermostat, ThermostatDevice) {
      val unused2 = update(Thermostat) { setTemperatureSetpointHoldDuration(60u) }
    }
  }
}

To change the temperature setpoint hold policy, which determines how and when a thermostat Hold state ends, call the ThermostatTrait.SetTemperatureSetpointHoldPolicyCommand.

Valid values are determined by TemperatureSetpointHoldPolicyBitmap.

Device API

val thermostatTraitFlow: Flow<Thermostat?> =
  thermostat.type(ThermostatDevice).map { it.standardTraits.thermostat }.distinctUntilChanged()

val thermostatTrait: Thermostat = thermostatTraitFlow.first()!!
if (thermostatTrait.supports(Thermostat.Attribute.temperatureSetpointHoldPolicy)) {

  // Set the temperature setpoint hold policy to holdDurationElapsedOrPresetChanged
  val unused =
    thermostatTrait.setTemperatureSetpointHoldPolicy(
      ThermostatTrait.TemperatureSetpointHoldPolicyBitmap(
        holdDurationElapsed = false,
        holdDurationElapsedOrPresetChanged = true,
      )
    )
}

val automation = automation {
  isActive = true
  sequential {

    // When someone says "Set my preferred hold duration",
    val unused =
      starter<_>(structure, VoiceStarter.OkGoogleEvent) {
        parameter(VoiceStarter.OkGoogleEvent.query("Set my preferred hold duration"))
      }

    // set the temperature setpoint hold policy to holdDurationElapsedOrPresetChanged
    action(thermostat, ThermostatDevice) {
      command(
        Thermostat.setTemperatureSetpointHoldPolicy(
          TemperatureSetpointHoldPolicyBitmap(
            holdDurationElapsed = false,
            holdDurationElapsedOrPresetChanged = true,
          )
        )
      )
    }
  }
}