Wake-up Light Part 1: Flipping switches

I’ve had the idea to build my own wake-up light for quite some time. This winter i finally got around to it. This is the first part of my write-up of the project.

In simple terms, the point of a wake-up light is to gently wake you up by slowly turning up the light before the alarm goes off in the morning. There are several commercial products available that do this already, all of which I think are either ugly, too small or simply not practical enough for my use case. Some of the things I wanted that are commonly not available in these products are:

• Big, powerful light. Usually, products are night stand-size alarm clocks with a few measly watts of power.
• RGB controllable light. My living room is also my bedroom. If I’m going to make the wake-up light big and powerful, I also want to be able to set it to a cosy warm evening-setting. Plus, this would make it able to do a more sunrise-like color fade in the morning.
• Powerful scheduling options. I’m a student and don’t get up at regular hours every day. I want the wake-up time to be easily settable, preferably synchronized to my alarm or even my schedule.

Flipping some switches

I figured I could use my Raspberry Pi as the central point for the system. It’s hanging off the back off my TV, running Raspbmc and is on 24/7 anyway, so a simple start would be to add a cronjob to simply turn on some lights in the morning. I already had 433 MHz light switches connected to three ambient lights in my room, so I started out with by hooking up a transmitter to the Pi.

Having someone in Shenzen send me a transmitter/receiver pair for 433 MHz on Ebay set me back about the same amount sending a normal letter home to my mother would. Mine was titled “RF Wireless Transmitter & Receiver Kit Module 433Mhz for Arduino/ARM/MCU WL”.

Obviously, someone on the Internetz already wrote the code to talk to my outlets using Arduino. And someone else also ported it to Raspberry Pi. Sweet! The project I’m using is called rcswitch-pi. According to the readme, it depends on the (seemingly useful) wiringpi project, so first we need to get that (assuming you have git installed):

$ cd
$ git clone git://git.drogon.net/wiringPi
$ cd wiringPi
$ ./build

Wiringpi is used for the gpio calls inside rc-switch and is sort of replacing the Arduino’s digitalWrite() and the like. Now let’s install rcswitch-pi:

$ cd
$ git clone https://github.com/r10r/rcswitch-pi.git
$ cd rcswitch-pi
$ make

The program is hardcoded to have the transmitter connected to Wiringpi pin 0, which corresponds to pin 11 of the GPIO header on the Pi. If you want, you can change this by editing send.cpp and running the make command again.

Hooking up the receiver to my Arduino and using the original rc-switch library, I figured out what group and channel corresponded to the buttons on my remote.

I could now control the lights from the Pi using these commands:

$ cd ~/rcswitch-pi
$ sudo ./send 11111 3 1 #Press "C on"
$ sudo ./send 11111 3 0 #Press "C off"
$ sudo ./send 11111 4 1 #Press "D on"
$ sudo ./send 11111 4 0 #Press "D off"

A small explaination to all these numbers: my outlets have “group switches” allowing different remotes to control  different sets of outlets. I have mine set to 11111. The buttons on the remote are labeled A-D. I have some lights hooked up to C (3) and D (4). All this I learned by loading the example sketch from the rc-switch library onto my Arduino and observing the serial output as I pushed some buttons on the remote.

Once I knew the send command was working, I linked it into /usr/bin/. This makes it possible to run the command without having to cd into the folder every time, which will be convenient for scheduling later.

$ sudo ln -s ~/rcswitch-pi/send /usr/bin/send
$ cd
$ sudo send 11111 3 1
$ sudo send 11111 3 0

Next time: Scheduling!