LedBanner

Project LedBanner
Status	Completed
Contact	User:Juerd
Last Update	2013-12-14

Introduction

The LED banner is an active RGB LED display, consisting of 8 rows of 80 pixels each fixed on a flexible banner. A Raspberry Pi drives it.

The following can be displayed:

• scrolling fixed images
• scrolling text in various colours
• animated GIFs
• etc.

The use of a flexible banner makes it easy to transport and easy to put up.

Youtube video

Hardware

The hardware consists of the following parts:

Raspberry Pi

A Raspberry Pi is used because it can be controlled over the network, can run perl scripts and has a fast SPI port to drive the LEDs.

Power supply

The power supply has been chosen to supply sufficient current for the LEDs. When the space is closed, the Raspberry Pi stays powered from the "standby 5V" output, while the LEDs are powered down.

LED strips

The display consists of 8 pieces of LED strip of 80 LEDs each. They are arranged in a left-to-right zig-zag manner for ease of connecting them in series.

The LED strip consists of pairs of RGB LEDs, where each pair is controlled by an LPD8806. See [1] for more information on driving these chips.

Flexible banner

The banner itself is custom made, with metal eyelets in each corner for fixation.

Software

The software runs on the Pi and is mostly written in Perl.

Display server

To drive the LEDs, a display server written in C does the low-level driving of the LEDs over the SPI port. It also controls the white balance and takes care of gamma correction.

Sources

• ledbanner display server source code
• nyancat, a set of small C programs to generate animated GIFs of 80x8 pixels, written specifically for the LedBanner.