Writing on dot matrix display with phototransistor pen

This technique is rather simple, but probably not many are using it. Kathy Yang shared his experiments where LED matrix is turned in to drawing board. Arduino UNO and 74LS138 ic’s take care of addressing each pixel on LED matrix. Phototransistor is used to read pixel coordinates and so the light corresponding LED. Whole trick lies upon scanning matrix lines with LEDs dimmed so it wouldn’t be looking as lit, but enough to be detected by phototransistor with comparator circuit. With a bit more polishing it could be really fun project to do with kids or even great learning kit to teach writing letters or numbers. Another use could be user interface, where one’s could change settings directly on display. Continue reading

Arduino based Tetris uses bi-color LEDs

Tetris game is around for 30 years. It is still alive in various forms and shapes. It is simple and addictive. You can get it as portable game devices, apps for smart-phones or PCs. Or you can make one by yourself with few building blocs and a bit of code. jollifactory has shared his Tetris game project that he built by using Arduino Nano board, couple chain-able bi-color matrix matrix modules, speaker and four push buttons. It looks great when placed in custom blue acrylic enclosure. Continue reading

Versatile LED matrix dice machine

Rolling dice is a common way of generating random numbers for many board games. I think it is always more fun to roll real physical dice to get number for next turn. It is practically true random number as physical world always brings some entropy. Anyway there are other ways of getting random numbers. Walter has focused on building LED matrix dice – an Arduino based random generator. Having Arduino on board, he didn’t limit himself with just couple of dices. He also added a row of other randomness. He simulated such things as coin flip, various dice modes for different games like dungeons and dragons. Also his machine randomly shuffles cards where player can draw a card. Also it gives ability to generate HEX and bin numbers and lastly it can help generate passwords. After he put electronics in a portable box, it really became helpful gadget in many situations. Continue reading

Bluetooth enabled LED matrix

LED matrix is a great way of displaying either text pr graphical messages. The more dots you have – the more freedom you get. In other hand when number of dots increases, you got to think about easy way of sending messages to it. lucadentella decided to go with Bluetooth option. He assembled Arduino circuit on the bottom of LED matrix which is driven by HC1632C controller. Arduino takes care of receiving Bluetooth messages from HC-05 Bluetooth module. Special care was taken on powering the thing. First of all he added LiPo battery charging and monitoring circuit. Then another circuit is used to rice LiPo battery voltage to 5V. Arduino accepts simple Bluetooth messages using basic protocol, so any device like Android smartphone can be used to send data. Continue reading

Laser pointer controlled LED matrix game

This is a little cute game cube that is controlled only by simple laser pointer. The game itself is very simple – you have to shoot falling dots on LED matrix screen with laser pointer as long as you can to gain more points. During time dots fall faster and faster what makes it really challenging to beat previous records. Laser Command from Eiji Hayashi on Vimeo. But probably the most interesting part in its game is laser pointer detection technology. As sensing device it uses LED matrix itself. To do so there are two measurement techniques (reverse bias and direct measurement) used where one detects the row and second column at which LED laser is pointed. Game is controlled by Arduino mini board. Continue reading