More light!
Charly's Column – Hue and Rasp Pi
Since his Trådfri Smarthome article over a year ago, sys admin columnist Charly has been receiving messages from readers with two questions: "Can you do that with the Philips' Hue system?" and "Can this also be done with a normal brightness sensor?" Yes and yes!
In a previous issue [1], I described how I control a smart light in my living room with Ikea's Trådfri system and Linux. The darker it gets, the more I turn up the lights. Around the same time, Martin Loschwitz then explained how he used a Raspberry Pi and a transmitter module to control Hue and other Zigbee devices [2].
Now I'm going to do it again, without the Zigbee module, but I expect to use a Hue bridge, which Martin's approach doesn't need, and because not everyone has a roof-top photovoltaic system, this time I focused on a simple brightness sensor.
Getting Started
First, I discovered the IP address of my Hue Bridge: 10.0.0.8. Then I pressed the button on the bridge and entered the following at the command line:
curl --data "{\"devicetype\": \"huelr\"}" http://10.0.0.8/api
The huelr
string (for "Hue living room") is freely selectable. I got some output like:
[{"success":{"username":"T3VGtGWmFUgJwHufxkudY1bizvqoZMhCSqu1ySwm"}}]
This unpronounceable string is an authentication string, which I have to specify with every call in the future. A (confusing) list of all connected devices is returned by the command:
curl --request GET 10.0.0.8/api/T3VGtGWmFUgJwHufxkudY1bizvqoZMhCSqu1ySwm
If you only need information about lights, you can append /lights
to the command or /lights/1
, /lights/2
, and so on for each lamp. The following command switches lamp 1 to medium brightness (value 125
):
curl --request PUT --data "{\"bri\":125}" 10.0.0.8/api/T3VGtGWmFUgJwHufxkudY1bizvqoZMhCSqu1ySwm/lights/1/state
For the brightness sensor, I used a $2.00 module named BH1750 (online, e.g., [3]). I connected this to the I2C bus of a Raspberry Pi (Figure 1). I used the Zero W model with WiFi – it has to communicate with the bridge.
Cat's Eyes
Raspbian comes with almost everything you need, with only a few packages to add:
sudo apt install build-essential wiringpi i2c-tools python-smbus
The program in Listing 1 reads the sensor in the program I named lux
:
cc lux.c -lwiringPi mv a.out lux && chmod 755 lux
Listing 1
lux.c
01 #include <wiringPiI2C.h> 02 #include <stdio.h> 03 int main (void) { 04 int handle = wiringPiI2CSetup(0x23); 05 wiringPiI2CWrite(handle,0x10); 06 sleep(1); 07 int word=wiringPiI2CReadReg16(handle,0x00); 08 int lux=((word & 0xff00)>>8) | ((word & 0x00ff)<<8); 09 printf("%d \n",lux); 10 return 0; 11 }
If you run lux
, you will see the current measured value for the photo sensor in lux units. Depending on this, you can now control your smart lighting.
Infos
- "Charly's Column: libcoap" by Charly Kühnast, Linux Pro Magazine, issue 202, September 2017, pg. 49: http://www.linuxpromagazine.com/Issues/2017/202/Enlightened-libcoap/(language)/eng-US
- "Controlling Zigbee Devices with the Raspberry Pi" by Martin Loschwitz, Linux-Magazin, September 2017, pg. 76: http://www.linux-magazin.de/ausgaben/2017/09/raspi-spricht-zigbee/ [in German]
- Debo BH1750: https://www.ebay.com/i/292393778070?chn=ps
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.
-
Canonical Collaborates with Qualcomm on New Venture
This new joint effort is geared toward bringing Ubuntu and Ubuntu Core to Qualcomm-powered devices.
-
Kodi 21.0 Open-Source Entertainment Hub Released
After a year of development, the award-winning Kodi cross-platform, media center software is now available with many new additions and improvements.
-
Linux Usage Increases in Two Key Areas
If market share is your thing, you'll be happy to know that Linux is on the rise in two areas that, if they keep climbing, could have serious meaning for Linux's future.
-
Vulnerability Discovered in xz Libraries
An urgent alert for Fedora 40 has been posted and users should pay attention.
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.