---
layout: page
title: "aREST Sensor"
description: "Instructions on how to integrate aREST sensors within Home Assistant."
date: 2015-09-07 18:15
sidebar: true
comments: false
sharing: true
footer: true
logo: arest.png
ha_category: DIY
ha_iot_class: "Local Polling"
ha_release: pre 0.7
---

The `arest` sensor platform allows you to get all data from your devices (like Arduinos with a Ethernet/Wifi connection, the ESP8266, and the Raspberry Pi) running the [aREST](http://arest.io/) RESTful framework.

## {% linkable_title Configuration %}

To use your aREST enabled device in your installation, add the following to your `configuration.yaml` file:

```yaml
# Example configuration.yaml entry
sensor:
  - platform: arest
    resource: https://IP_ADDRESS
    monitored_variables:
      temperature:
        name: temperature
    pins:
      A0:
        name: Pin 0 analog
```

{% configuration %}
resource:
  description: "IP address and schema of the device that is exposing an aREST API, e.g., https://192.168.1.10."
  required: true
  type: string
name:
  description: Let you overwrite the name of the device.
  required: false
  default: aREST sensor
  type: string
pins:
  description: List of pins to monitor. Analog pins need a leading **A** for the pin number.
  required: false
  type: list
  keys:
    pin:
      description: Pin number to use.
      required: true
      type: list
      keys:
        name:
          description: The name of the variable you wish to monitor.
          required: true
          type: string
        unit_of_measurement:
          description: Defines the unit of measurement of the sensor, if any.
          required: false
          type: string
        value_template:
          description: Defines a [template](/docs/configuration/templating/#processing-incoming-data) to extract a value from the payload.
          required: false
          type: template
monitored_variables:
  description: List of exposed variables.
  required: false
  type: list
  keys:
    variable:
      description: Name of the variable to monitor.
      required: true
      type: list
      keys:
        name:
          description: The name to use for the frontend.
          required: false
          type: string
        unit_of_measurement:
          description: Defines the units of measurement of the sensor, if any.
          required: false
          type: string
        value_template:
          description: Defines a [template](/docs/configuration/templating/#processing-incoming-data) to extract a value from the payload.
          required: false
          type: template
{% endconfiguration %}

The variables in the `monitored_variables` array must be available in the response of the device. As a starting point you could use the one of the example sketches (eg.  [Ethernet](https://raw.githubusercontent.com/marcoschwartz/aREST/master/examples/Ethernet/Ethernet.ino) for an Arduino with Ethernet shield). In those sketches are two variables (`temperature` and `humidity`) available which will act as endpoints.

Accessing one of the endpoints (eg. http://192.168.1.10/temperature) will give you the value inside a JSON response.

```json
{"temperature": 23, "id": "sensor01", "name": "livingroom", "connected": true}
```

The root will give you a JSON response that contains all variables and their current values along with some device details.

```json
{
   "variables" : {
      "temperature" : 23,
      "humidity" : 82
   },
   "id" : "sensor01",
   "name" : "livingroom",
   "connected" : true
}
```

`return_value` contains the sensor's data in a JSON response for a given pin (eg. http://192.168.1.10/analog/2/ or  http://192.168.1.10/digital/7/). 

```json
{"return_value": 34, "id": "sensor02", "name": "livingroom", "connected": true}
```