YourITronics

This article is part of the PCB Giveaway program that we have running here at Youritronics. Morgoth will get a free pcb manufactured by BKRtech for submitting this project. If you’re interested in participating, read more on the program page.

These days most pharmacies use LED pharmacy crosses posted at their entrance to let people know there is a pharmacy there. The reasons are obvious, they look cool&hi-tech, they can be seen from distance and they can be customized really easy (well, easy customizing pretty much depends on how the manufacturer approaches things).

If you try to search the web about schematics or example codes for this kind of circuit you wont find any, and again i think the reason is obvious, the crosses are quite expensive and so is the profit for the manufacturer. So nobody is gonna post schematics for such a project, unless you’re a hobbyist and you’re having fun with electronics.

The project consists of one ATmega64, three ULN2003 and five 5×7 LED matrix from Kingbright(TA20-11EWA). I had the idea to build something like this but so far i haven’t had the time nor the knowledge to get it done. So i asked Morgoth if he would like to participate in the project. I sent him the LED’s, the drivers and the PCB and he started working. As you can see not many parts are involved , but the secret lies in the microcontroller, it’s the programming that does the job.

In the next pictures you can see the microcontroller board with the ULN2003 darlington arrays:

The circuit was designed to receive messages trough serial interface from a computer and than display them. Morgoth also designed a custom terminal for windows which provides easy access to the display.

In this test phase a serial interface by wire was used to transmit data between the terminal and the ATmega64, but a wireless or bluetooth module could be integrated with no problem.

Also as a note, the LED’s don’t light up really bright, for that to happen you need to use drivers on the positive rail. This also applies if you’re planning to take the project to another level and use bigger LED’s

And now, watch some videos with the LED Pharmacy Cross beeing controlled from the computer:

• LED Pharmacy Cross ATmega source code
• LED Pharmacy Cross terminal source code

The author, Olivier de Broqueville designed this circuit for hi’s son who was dreaming of a small tool able to write symbols or pictures on a screen. The solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds,  and a 16F628 , the dream could become reality.

Olivier also made a VB application that you can use to design patterns and export them apropriately.

Fancy LED matrix: [Link]

The project uses (2) 5×7 LED Displays, so 10 columns and 7 rows for a total of 70 LEDs.  The matrix works on the basis of scanning the display very quickly. The 4017 chip is used to switch between the columns. The way the 4017 chip works, is that when a signal is sent to a certain pin, 1 of 10 of the other pins is sequentially activated. The way the software works, is it tells the chip to switch columns, which sets one column high.

The software then makes the parallel port turn on the individual LEDs in that column needed. This is done very quickly, many times a second. It’s a fairly easy concept and it turned out the programming was easier than the author had initially anticipated.

And the great thing about this project is that it also comes with a font writer, which is basically a software written also by the author of the circuit to help him quickly design animations.

Computer Controlled LED Matrix: [Link]

Another useful application for a LED dot matrix display, well useful for those who use twitter. The purpose of the project is simple, it scrolls your twitters on the led matrix, this way you don’t have to be in front of your computer to see what’s new. Source codes and info about building it is provided by the author. The matrix is controlled by an Arduino

Physical LED Twitter Scrolls Your Twitters: [Link]

This project’s display is made of a number of tiles, about 2″ square with an 8 x 8 array of color LED pixels. Each tile is individually powered and animated, so your can freely pick them up and re-arrange them. To set up a display, the tiles are placed in a special tray. Animations are downloaded into the tray via Ethernet and stored locally on an EEPROM, or loaded via an SD card. The tray broadcasts the animation to each of the tiles, and then synchronizes them.

If the pieces are left in the tray, the animation can be updated continuously over the Ethernet connection. If the tiles are removed from the tray, they’ll display the animation for several hours with their own re-chargeable battery power. Once the animation is synchronized and running on the tiles, you can pick them up and place them anywhere.

Dynamic Tiled display: [Link] - [Via]