Posts with «pov» label
For those who haven’t addicted themselves to Super Hexagon yet, it’s pretty… addicting, to say the least. Normally this 80’s arcade-style game would run in a browser but some of the people at Club de Jaqueo in Buenos Aires decided to cram all of that into an Arduino. They didn’t stop there, though, and thought that it would work best with a POV display.
To navigate the intricate maze of blending a POV display with a fast-paced game like this, the group turned to the trusty Arduino Micro. After some frustration in the original idea, they realized that the game is perfectly suited for a POV display since it’s almost circular. The POV shouldn’t take up too much of the processing power of the Arduino, so most of the clock cycles can be used for playing the game. They couldn’t keep the original name anymore due to the lack of hexagon shape (and presumably copyrights and other legal hurdles), but the style of the original is well-preserved.
The group demonstrated their setup this past weekend, and the results are impressive judging by the video below. They’ve also released their source code and schematics as well, in case you have an old fan (or maybe even a bicycle?) lying around that is just begging to be turned into a mini-arcade game.
Filed under: Arduino Hacks
[Alex] needed a project for his microcomputer circuits class. He wanted something that would challenge him on both the electronics side of things, as well as the programming side. He ended up designing an 8 by 16 grid of LED’s that was turned into a game of Tetris.
He arranged all 128 LED’s into the grid on a piece of perfboard. All of the anodes were bent over and connected together into rows of 8 LED’s. The cathodes were bent perpendicularly and forms columns of 16 LED’s. This way, if power is applied to one row and a single column is grounded, one LED will light up at the intersection. This method only works reliably to light up a single LED at a time. With that in mind, [Alex] needed to have a very high “refresh rate” for his display. He only ever lights up one LED at a time, but he scans through the 128 LED’s so fast that persistence of vision prevents you from noticing. To the human eye, it looks like multiple LED’s are lit up simultaneously.
[Alex] planned to use an Arduino to control this display, but it doesn’t have enough outputs on its own to control all of those lights. He ended up using multiple 74138 decoder/multiplexer IC’s to control the LED’s. Since the columns have inverted outputs, he couldn’t just hook them straight up to the LED’s. Instead he had to run the signals through a set of PNP transistors to flip the logic. This setup allowed [Alex] to control all 128 LED’s with just seven bits, but it was too slow for him.
His solution was to control the multiplexers with counter IC’s. The Arduino can just increment the counter up to the appropriate LED. The Arduino then controls the state of the LED using the active high enable line from the column multiplexer chip.
[Alex] wanted more than just a static image to show off on his new display, so he programmed in a version of Tetris. The controller is just a piece of perfboard with four push buttons. He had to work out all of the programming to ensure the game ran smoothly while properly updating the screen and simultaneously reading the controller for new input. All of this ran on the Arduino.
Filed under: Arduino Hacks, led hacks
[Sholto] hacked together this ultra low-budget spinning display. He calls it a zoetrope, but we think it’s actually an LED based Persistence Of Vision (POV) affair. We’ve seen plenty of POV devices in the past, but this one proves that a hack doesn’t have to be expensive or pretty to work!
The major parts of the POV display were things that [Sholto] had lying around. A couple of candy tins, a simple brushed hobby motor, an Arduino Pro Mini, 7 green LEDs, and an old hall effect sensor were all that were required. Fancy displays might use commercial slip rings to transfer power, but [Sholto] made it work on the cheap!
The two tins provide a base for the display and the negative supply for the Arduino. The tins are soldered together and insulated from the motor, which is hot glued into the lower tin. A paper clip contacts the inside of the lid, making the entire assembly a slip ring for the negative side of the Arduino’s power supply. Some copper braid rubbing on the motor’s metal case forms the positive side.
[Sholto] chose his resistors to slightly overdrive his green LEDs. This makes the display appear brighter in POV use. During normal operation, the LEDs won’t be driven long enough to cause damage. If the software locks up with LEDs on though, all bets are off!
[Sholto] includes software for a pretty darn cool looking “saw wave” demo, and a simple numeric display. With a bit more work this could make a pretty cool POV clock, at least for as long as the motor brushes hold up!
Filed under: led hacks
Building a Persistence of Vision globe is pretty awesome, but overlaying a Death Star pattern on the display takes it to the next level of geekery. Like us, [Jason] has wanted to build one of these for a long time. His success pushes us one step closer to taking the plunge and we hope it will inspire you to give it a shot too.
As he mentions in the beginning of his write up, the mechanical bits of these displays are really where the problems lie. Specifically, you need to find a way to transfer power to the spinning display. In this case use went with some DC motor brushes. These are replacement parts through which he drilled a hole to accept the metal axles on top and bottom. We hadn’t seen this technique before, but since motor brush replacements are easy to find and only cost a few bucks we’d say it’s a great idea.
The 24 blue LEDs that make up the display are all on one side of the PCB. They’re driven by an ATmega328 running the Arduino bootloader. [Jason] uses an FTDI adapter to program the chip. Don’t miss the video embedded after the break.
Filed under: led hacks
With this POV light painter, you can paint the town red or any other color that suits your fancy. The LightScythe is a 2-meter long POV tube made up of multi-color LED strips. POV stands for Persistence of Vision which describes how our eyes see motion blur when an object is moving quickly. In this case, it enables us to see a message written with light.
An image is loaded onto a laptop which converts it to serial data, then sends it to an Arduino which controls the lightbar. A camera is set for 10 to 15 seconds of exposure, during which time the user walks across the frame, painting the image to be caught by the camera. Check out the full build instructions.