Internet of Things Example – An E-mail Alert Water Fountain - Raspberry Pi Mechatronics Projects - page 97

Controlling RGB LEDs from
a web page
In this task, we will learn how to control the RGB LEDs from a web page. We will use the
digitally controlled RGB LED strip from Adafruit Industries. We will interface a color picker
and set the color of the RGB strip. The color picker wheel was borrowed from circadian
lighing project , Chris Fane , distributed under MIT license. ( https://github.com/
rasathus/circadianLighting ). We will modify this code sample to suit our needs.
We'll also use the LPD8806 library writen by Adam Haile, distributed under GPL v3 license.
( https://github.com/adammhaile/RPi-LPD8806.git ).
Prepare for lift off
Since we are using the digitally addressable RGB LED strip, we need to enable the SPI drivers
on the Raspberry Pi.
Enabling of SPI drivers is not necessary if the you have installed Occidentalis in
Project 2 , A Raspberry WebIDE Example .
The following file needs to be modified: /etc/modprobe.d/raspi-blacklist.conf .
The blacklist spi-bcm2708 line needs to be commented out (add a # at the start of the
line). Then we get the drivers working by execuing the following command:
sudo modprobe spi_bcm2708
The SPI devices can be found listed in the /dev directory:
SPI devices listed in the directory