LED Open Sign and Controller – Open Source Project

Created on: 22 September 2012

In this open source hardware and firmware project, an LED "Open" sign is built using an ATtiny2313 microcontroller. This is the type of sign that would typically be used in a shop or restaurant to show that it is open for business. This sign flashes the LEDs on and off in various ways to attract customers attention.

Although this project is for building an open sign, it can be adapted to build any LED sign of your choice.

This video shows the finished Open sign project operating:

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LED Open Sign Project Overview

The Enclosure

The enclosure front and back are made of 3mm thick hardboard. The sides are made from 18mm thick MDF. Other types of wood could also be used to construct the enclosure.

The finished enclosure is 616mm long by 229mm high by 54mm deep.

The holes drilled in the front of the enclosure for the LEDs have been spaced so that a drill template can be printed on two A4 sized sheets of paper.

The Microcontroller Board

The microcontroller board for this project contains a 5V regulator circuit that supplies the ATtiny2313 AVR microcontroller with 5V. The AVR microcontroller drives ten transistors which in turn drive sets of LEDs.

The board actually has 12 transistors (or channels) for driving LEDs as well as space for two push buttons. Only 10 of the transistors are needed for this open sign and the push buttons are not needed.

The Power Supply

The LED sign project is powered by a 12V d.c. power supply. This is an external "wall wart" type power supply with barrel connector.

Wiring the LEDs

The LEDs are wired in the following way:

• Each letter (O, P, E and N) is controlled by its own single channel – this uses 4 channels
• The line above the letters is wired so that every third LED is connected together – this uses 3 channels
• The line below the letters is wired so that every third LED is connected together – this uses 3 channels

To clarify how the lines of LEDs are wired together: The first LED, fourth LED, seventh LED, etc. are all wired together and controlled by a single channel. The second, fifth, eighth, etc. LEDs are wired together and controlled by a single channel. The third, sixth, ninth, etc. LEDs are wired together and controlled by a single channel.