Hardware Hacking Projects for Geeks

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Chapter 8, How to Hack a Building-Size Display

Software Setup Instructions

There are two versions of the software that you can run depending on

which size system you have built. If you’re building the large building-size

system, go to the Large-scale software section. If you’re building the home

or desktop system, go to the Small-scale software section.

Large-scale software

Three computers are used to control the building-size Blinkenlights system.

Although it would have been possible to put it all on one system, the CCC

decided to separate the modules (control, playback, telephone interactiv-

ity) in order to allow distributed development and operation. Since the

modules communicate using standard network protocols, you can run all

of the software on a single machine. Control of the system is from either

an email interface or from a GSM mobile phone. This flow of data can be

seen in Figure 8-23.

Download the software from http://www.blinkenlights.de/blinkentools.

en.html and install it according to the included files. The site also includes a

software simulator that allows you to design and preview animations with-

out having to first set up the hardware. You may want to play around with

the software simulator first to get a feel for how the processes interact.

The software is partitioned into three components:

• Chaos Control Center (the module name is “blccc”)

• Matrix Control (the module name is “windowmatrixd”)

• Telephone interface (the module name is “blinkenisdn”)

These three processes use UDP to communicate.

The Chaos Control Center module reads a playlist and broadcasts frame

packets to the Matrix Control module. The “windowmatrixd” process then

extracts these frames and writes them to the 8,255 digital output ports.

Figure 8-23: Software overview

email

Phone

call

Blinkenlights

movie archive

ISDN

interface

Chaos

control

center

Matrix

control

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Part II: Advanced Hacks, Tools, and Techniques

The telephone interface process sends telephone line state information

(ONHOOK, OFFHOOK) and event information (DTMF keys pressed)

for each line to the Chaos Control Center. This module was designed for

an ISDN interface, and so will require some hacking to support a different

interface. Whenever the telephone interface detects an OFFHOOK event

(an incoming call is detected and answered), it starts the Pong game. When

the telephone interface detects an ONHOOK event (the calling party hangs

up the phone), the system returns to the playlist movies.

Since all of the processes will be run on a single machine, you need to

change all the target addresses to 127.0.0.1 so that everything runs locally.

Locate one animation and run it. Watch the building display to make sure

that everything is wired properly. You may need to correct wiring mistakes

at the interconnect boards. Try a few of the animations from the web site

and design a few of your own.

The Pong-like game was designed to

work with an ISDN phone system, but

you may be able to hack the code a bit

to make it work with a standard PSTN

system.

Small-scale software

If you have built the desktop- or home-

size version, download the mini-

Blinkenlights software from http://

www.jalcds.de/blinkenleds/software.

php. Install this software according

to the included instructions. The soft-

ware runs under Windows and can

utilize all of the original Blinkenlights

movie files. This software is all you

need to run the smaller version of the

system. When running, it will look

like Figure 8-24.

After you’ve wired and connected the

LED and wire mesh to the LED driv-

ers, test out the system before you

mount it.

Figure 8-24: Small-scale PC software

Software Setup Instructions

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