aphexddb / lightshow

RGB LED light effects and things for the Raspberry Pi

lightshow

RGB LED light effects and things for the Raspberry Pi.

Arduino's are tricky for anything fancy regarding services, limited in RAM and plus I wanted to use Golang. Getting software PWM to work on a RPI is a bit of a challenge! All dependencies are vendored for convenience.

This project not possible without the original Arduino github.com/sowbug/G35Arduino project for inspiration and WiringPi

Hardware

This project uses a Raspberry Pi 3 and GE Color Effects Lights that you can buy at Lowe's. You should be able to support other LED pixels if you know what you are doing around timings and such.

Pi Model 3 Pinout Reference:

Raspberry PWM Pinout:

Header Pin	Name	BCM GPIO
12	PWM0	18

Linux Setup

• Used Minibian distro. Setup your SSH access as you prefer, default user is root / raspberry.
• Used ethernet for internet access, you can do wifi if you please

PWM Support via Pi Blaster

1. Disable Raspberry Pi audio (it uses PWM). You will need to blacklist the Broadcom audio kernel module by creating a file /etc/modprobe.d/snd-blacklist.conf with

   blacklist snd_bcm2835
   

   If the audio device is still loading after blacklisting, you may also need to comment it out in the /etc/modules file. Some distributions use audio by default, even if nothing is being played. If audio is needed, you can use a USB audio device instead.

2. Install latest Pi firmware

   wget https://raw.githubusercontent.com/Hexxeh/rpi-update/master/rpi-update
   bash rpi-update
   

   Reboot the pi

3. Install Pi Blaster

sudo apt-get install pi-blaster

pi-blaster creates a special file (FIFO) in /dev/pi-blaster. Any application on your Raspberry Pi can write to it (this means that only pi-blaster needs to be root, your application can run as a normal user).

Important: when using pi-blaster, the GPIO pins you send to it are configured as output.

To set the value of a PIN, you write a command to /dev/pi-blaster in the form <GPIOPinName>=<value> where must be a number between 0 and 1 (included).

You must use the GPIO number (BCM xx in the diagram below).

Running

go build
./lightshow

Links

To investigate

• go bindings for Raspberry Pi PWM library for WS281X LEDs

  • Userspace Raspberry Pi PWM library for WS281X LEDs

• Different Styles of Pixels

• Pixel Wiring Colors

• GE Color Effects Bulbs

  • Hacking the remote

• Arduino GECE library

  • Related forum thread on using it

• Another blog post on hacking the GE lights

PWM and GPIO things

• Python and RPi.GPIO
• Customize GPIO and PWM clock on linux
• How to use GPIOs on raspberry pi (Simple I/O, PWM and UART)
• Raspberry Pi GPIO via the Shell
• Wiring Pi
  • WiringPi-Go: Golang wrapped version
• pi golang gpio module

Lights and LED

• Hacking Christmas Lights - GE Color Effects