Light Sequencer

I have been working on a light display for the holidays that is synchronized to music. Some files have been posted to GitHub but I’m still working out the kinks.

This is more of a bank of knowledge for me to recreate this project should anything happen to corrupt my set up. But ya’ll are more than welcome to the info.

Derived from lightorgan.c which is used to control GPIO pins with midi playback in ALSA. The source and instructions are available at:

lightorgan8.c – Modified to use 1st eight pitch of scale rather than approximating across the entire 12 pitch scale.

lightsequence.c – modified further to allow user to indicate 8 or 16 relay/pin control. Uses midi channels 0 for 8ssr and 1 for 16ssr.

Starting from scratch on the Raspi, you need to install:

Raspi OS (Raspbian, Debian, etc.) (
timidity (apt-get install timidity)
ALSA Devel libs (should already be present)
Gordon's wiringPi library (

(git clone git:// Build it from the wiringPi directory:  cd wiringPi ./build  Test it:  gpio -v gpio readall 

Need GIT? – (sudo apt-get install git-core)

Optionally, if you want the original lightorgan. You will need subversion to grab a copy. subversion (apt-get install subversion) lightorgan (svn checkout

Timidity stock settings are too aggressive for the Pi, modify the /etc/timidity/timidity.cfg file. Uncomment these lines and restart Timidity.

opt EFresamp=d #disable resampling opt EFvlpf=d #disable VLPF opt EFreverb=d #disable reverb opt EFchorus=d #disable chorus opt EFdelay=d #disable delay opt anti-alias=d #disable sample anti-aliasing opt EWPVSETOZ #disable all Midi Controls opt p32a #default to 32 voices with auto reduction opt s32kHz #default sample frequency to 32kHz


Pin chart at:

Connect pins as appropriate to your setup.

MIDI file creation:

You should be able to use any midi file but the purpose of this program is to design a specific light sequence. I’ve been using the open source program, Aria Maestosa, to drop notes into patterns on channel 0 on the 8 notes starting at C. Each note toggles a corresponding relay on/off. The midi sounds terrible when played but gives me a complete control of the pattern. An MP3 is played to the speaker and the Midi file is played to the GPIO.

Test files included in the repo:

midilighttest8.mid – Tests playing first 8 notes on Channel 0. Cycles pins from 0 to 7 in progressively faster scales. 1/4 second notes through 1/32 second notes.

midilighttest16.mid – Eight notes played on each Channel, 0 and 1. Untested until I get another SSR board.

Sample terminal command:

sudo lightorgan8
mpg123 mortalkombat2.mp3 & sleep 2.35 && aplaymidi –p 14:0 mcnodrum.mid 


1 thought on “Light Sequencer

  1. hello! Did you ever finish this to work with more than 8 relays? i’d love to use it for an art project I’m building controlling 16 solenoids but I can’t get it to work beyond 8. Please contact me! tomsepe


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