hew

Hew is small Clojure program to make a Philips Hue light emit a color based on (or hew to, if you wish) a temperature reading.

In the current version it can acquire temperature readings from either:

• An OWFS server with a 1-wire temperature sensor, or
• A Philips Hue Motion sensor, such as Outdoor sensor, as these are equipped with a temperature sensor in addition to the motion and ambient light sensors.

The temperature is read, and the light is updated, every five minutes. The Hue temperature sensor seems to be sending updates to the bridge every five minute while OWFS readings are generally instant.

Writeups:

• Original: https://weakreference.medium.com/shorts-or-jeans-f2f1783dc7a4
• Revisited: https://weakreference.medium.com/shorts-or-jeans-revisited-e2fc7f9c9559

What you need

A Philips Hue lighting system

The Philips Hue lighting system connects LED bulbs and other light sources and accessories using ZigBee to your home network using a Hue bridge. The bridge connects to your network using Ethernet and exposes a RESTful HTTP interface which is used by hew to control the lights. Note that not all Hue products need a Hue bridge, but a bridge is required for hew to work. hew needs to be able to access the bridge over the local network, remote access is not supported.

You need one bulb/lamp/lightstrip capable of emitting multi-colored light, and, unless you use 1-Wire, a Hue motion sensor for measuring the temperature.

Optionally: A 1-Wire temperature sensor network

1-Wire is a device communications bus system which can be used to connect temperature sensors among other things. Hew expects temperature readings to be sourced from a 1-Wire sensor net by use of 1-Wire File System, OWFS. Specifically, hew expects an OWFS server available to which it can connect and obtain temperature readings.

A JDK and Leiningen

Hew is written in Clojure. To build and run it you'll need a current JDK and Leiningen.

Configuration

Configuration is provided to the application using environment variables:

Using a Hue motion sensor for obtaining temperature readings:

USE_OWFS=false 
HUE_HOST=<ip of Hue bridge> 
HUE_USER_ID=<Hue bridge user id, see below> 
HUE_LIGHT_NAME=<Name of Hue light to control, as seen in the Hue App> 
HUE_SENSOR_ID=<ID of the Hue temperature sensor, see below>

Using an OWFS server for obtaining temperature readings:

USE_OWFS=true
OWFS_HOST=<owfs host/ip>
OWFS_PORT=<owfs port> 
HUE_HOST=<ip of Hue bridge> 
HUE_USER_ID=<Hue bridge user id, see below> 
HUE_LIGHT_NAME=<Name of Hue light to control, as seen in the Hue App> 

Obtaining a Hue Bridge User ID

If you have not done so, you need to create a user for the Hue bridge by following the instructions on the Philips Hue developer site.

Obtaining the ID of the Hue temperature sensor

The temperature sensing capability of the Hue motion sensors is somewhat of a hidden feature. It doesn't show up in the Hue app (but is supported by some third-party systems, such as Apple's HomeKit), and in the Hue API it is exposed as a separate sensor that requires a bit of digging to find:

Issue an HTTP GET request to http://<hue-bridge-address>/api/<hue-bridge-user-id>/sensors and look for sensors of type ZLLTemperature. The ID to look for is the associated int, i.e. 79 in this example response fragment:

[...]
 }
  },
  "79": {
    "state": {
      "temperature": 832,
      "lastupdated": "2021-04-28T08:07:45"
    },
    "swupdate": {
      "state": "noupdates",
      "lastinstall": "2020-11-08T13:45:47"
    },
    "config": {
      "on": true,
      "battery": 100,
      "reachable": true,
      "alert": "none",
      "ledindication": false,
      "usertest": false,
      "pending": []
    },
    "name": "Hue outdoor temp. sensor 1",
    "type": "ZLLTemperature",
    "modelid": "SML002",
    "manufacturername": "Signify Netherlands B.V.",
[...]

The following jq expression lists all temperature sensor IDs known to the bridge, along with the latest captured temperature:

curl http://<hue-bridge-address>/api/<hue-bridge-user-id>/sensors \
| jq '[. |  to_entries[] | select ( .value.type | contains("ZLLTemperature")) | {id: .key, temperature: (.value.state.temperature / 100), lastupdated: .value.state.lastupdated}]'

Clone, build and run

Clone the Git repository and build using Leiningen:

lein uberjar

Set required environment variables and run:

USE_OWFS=false HUE_HOST=192.168.0.1 HUE_USER_ID=hue-user-id HUE_LIGHT_NAME=Bloom HUE_SENSOR_ID=79 java -jar target/uberjar/hew.jar 

Copyright © 2016-2021 Patrik Fredriksson

Distributed under the MIT License.