home-assistant.io/source/_components/binary_sensor.trend.markdown
2018-10-03 12:42:57 +02:00

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---
layout: page
title: "Trend Binary Sensor"
description: "Instructions on how to integrate Trend binary sensors into Home Assistant."
date: 2016-09-05 10:00
sidebar: true
comments: false
sharing: true
footer: true
ha_category: Utility
logo: home-assistant.png
ha_release: 0.28
ha_iot_class: "Local Push"
ha_qa_scale: internal
---
The `trend` platform allows you to create sensors which show the trend of
numeric `state` or`state_attributes` from other entities. This sensor requires
at least two updates of the underlying sensor to establish a trend.
Thus it can take some time to show an accurate state. It can be useful
as part of automations, where you want to base an action on a trend.
## {% linkable_title Configuration %}
To enable Trend binary sensors in your installation,
add the following to your `configuration.yaml` file:
```yaml
# Example configuration.yaml entry
binary_sensor:
- platform: trend
sensors:
cpu_speed:
entity_id: sensor.cpu_speed
```
{% configuration %}
sensors:
description: List of your sensors.
required: true
type: map
keys:
entity_id:
description: The entity that this sensor tracks.
required: true
type: string
attribute:
description: >
The attribute of the entity that this sensor tracks.
If no attribute is specified then the sensor will track the state.
required: false
type: string
device_class:
description: >
The [type/class](/components/binary_sensor/) of
the sensor to set the icon in the frontend.
required: false
type: string
friendly_name:
description: Name to use in the Frontend.
required: false
type: string
invert:
description: >
Invert the result. A `true` value would
mean descending rather than ascending.
required: false
type: boolean
default: false
max_samples:
description: Limit the maximum number of stored samples.
required: false
type: integer
default: 2
min_gradient:
description: >
The minimum rate at which the observed value
must be changing for this sensor to switch on.
The gradient is measured in sensor units per second.
required: false
type: string
default: 0.0
sample_duration:
description: >
The duration **in seconds** to store samples for.
Samples older than this value will be discarded.
required: false
type: integer
default: 0
{% endconfiguration %}
## {% linkable_title Using Multiple Samples %}
If the optional `sample_duration` and `max_samples` parameters are specified
then multiple samples can be stored and used to detect long-term trends.
Each time the state changes, a new sample is stored along with the sample time.
Samples older than `sample_duration` seconds will be discarded.
A trend line is then fitted to the available samples, and the gradient of this
line is compared to `min_gradient` to determine the state of the trend sensor.
The gradient is measured in sensor units per second - so if you want to know
when the temperature is falling by 2 degrees per hour,
use a gradient of (-2) / (60 x 60) = -0.00055
The current number of stored samples is displayed on the States page.
## {% linkable_title Examples %}
In this section you find some real-life examples of how to use this sensor.
This example indicates `true` if the sun is still rising:
```yaml
binary_sensor:
- platform: trend
sensors:
sun_rising:
entity_id: sun.sun
attribute: elevation
```
This example creates two sensors to indicate whether the temperature is
rising or falling at a rate of at least 3 degrees an hour,
and collects samples over a two hour period:
```yaml
binary_sensor:
- platform: trend
sensors:
temp_falling:
entity_id: sensor.outside_temperature
sample_duration: 7200
min_gradient: -0.0008
device_class: cold
temp_rising:
entity_id: sensor.outside_temperature
sample_duration: 7200
min_gradient: 0.0008
device_class: heat
```