Hackaday Links: June 29, 2014

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Ever see a really cool build on YouTube with no build details at all? Frustrating, right? That’s us with the NES Keytar covering the Game of Thrones theme. He’s using a Raspi with the sound chip in the NES to do live chiptunes. Freakin’ awesome. There’s also the ST:TNG theme as well.

A few years ago the folks at Oculus had an idea – because of cellphones, small, high resolution displays are really cheap, so why not make VR goggles? At Google IO this week someone figured out everyone already has a cellphone, so just wrap it in some cardboard and call it a set of VR goggles. You can get a kit here, but the only difficult to source components are the lenses.

What happens when you put liquid nitrogen under a vacuum? Well, it should evaporate more, get colder, and freeze. Then it breaks up into solid nitrogen snow. No idea what you would do with this, but there ‘ya go. Oh, [NC], we’re going to need a writeup of that LN2 generator.

About a month ago, the House4Hack hackerspace in South Africa told us of their plans to bring a glider down from 20km above the Earth. They finally launched it, The CAA only allowed them to glide back from 6km (20,000 feet), but even from there the foam glider hit 230kph (124 knots). That’s a little impressive for a foam FPV platform, and we’re betting something with a larger wingspan would probably break a spar or something. Shout out to HABEX.

All the electronic dice projects we’ve seen have one thing in common: they’re not cubes. Thus uberdice. It’s six nine-pixel displays on the faces of a cube, powered by a battery, and controlled by an accelerometer. Yes, it is by far the most complicated die ever made, but it does look cool.

Roll with Dicebot, the Tweeting Dice Roller

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[David] modernized a 1920’s dice rolling game to bring us DiceBot, a twitter enabled dice rolling robot. DiceBot started with an antique dice tin. The original tin was human controlled. Pushing a button on the side of the tin would spin the bottom, rolling the dice.

It’s a bit hard to push a button from across the world, so [David] added a small motor to spin the tin. He connected the motor to a simple L298 motor driver chip, and wired that up to a Raspberry Pi. The Pi runs a few custom Ruby scripts which get it on the internet and connect to the Twitter API.

Operation is pretty straightforward. A tweet to @IntrideaDiceBot with the hashtag #RollTheDice will cause the Dicebot to spin up the dice. Once things have settled, DiceBot captures an image with its Raspberry Pi camera. The dice values are checked using OpenCV. The results are then tweeted back, and displayed on DiceBot’s results page.

[Read more...]

A PIC powered pair of electronic dice

[Timothy] is honing his microcontroller skills with this electronic dice project. In addition to giving him an opportunity to work on some code, the use of an 8-pin chip provides a design challenge for driving the twelve pips and providing a user input.

The project started off with some $4 strings of LED Christmas lights. He promptly disassembled the strands, each yielding 100 LEDs. The microcontroller he chose to work with is a PIC 12F629. It’s DIP8 package provides six I/O pins to work with. When examined closely you will find that the pips on a die are always present in pairs with the exception of the center pip. This means that only four pins are needed to drive one die. You can see a pair of transistors above; one is a PNP, the other an NPN. These are both driven from the same uC line, which toggles between the pair of die. This accounts for 5 of the available pins, with the sixth monitoring the push button.

Dice gauntlet joins cosplay with D&D gaming

If you needed a reason to dress up for your next Dungeons & Dragons adventure this is surely it. Not only will this attractive wrist adornment go right along with your medieval theme, but the gauntlet doubles as a multi-sided digital die.

Sparkfun whipped up this tutorial which details the build. Yep, they’re hawking their own goods but we must say this is one of the few projects using sewable electronics which we thoroughly enjoy. It calls for several Lilypad modules, including an Arduino board, accelerometer, and slide switches. The switches let you select the number of sides for the die you are about to roll. The accelerometer starts the fun when you shake your wrist back and forth (that’s what she said). The project is powered by a rechargeable battery, which we always like to see, and uses a four-digit seven segment display located where the face of a wristwatch is normally found.

Of course, you could get the shaking action and use no batteries at all if you wish.

Electronic die rolls up to 100

If you’re gaming on the road, or just don’t have a die with the right number of sides on hand, an electronic polyhedral die will be quite handy. [Marcus] built this using a printed circuit board of his own design, and we think an electronically simple project like this is a great way to get your feet wet with PCB fab house techniques. He suggests Seeed Studios’ service, or the DorkBotPDX group PCB order. But this would not be a hard project to build on perfboard as well.

The concept is simple. A two-digit 7-segment display shows the value of the top face of your die. when it’s time to roll, just pick up the box and tip it over. A tilt switch senses this action and rolls the die by displaying the next pseudo-random number. The single button, seen here with a pyramid die glued to it, lets you select between die with different number of sides; from 2 (like a coin flip) all the way up to 100.

We like [Marcus'] projects. He’s the same guy that built a scoring system in a game storage box.

Battery-less electronic dice for all your D&D needs

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[Anthony] is a big fan of Dungeons & Dragons, but he thought the game would be far more fun to play with an electronic die rather than the traditional fare. Electronic dice are nothing new around here, though we can’t help but like his design.

He wanted to keep his electronic die as small as possible while ensuring it would last an entire gaming session, so rather than use a battery to power it, he opted for a super capacitor instead. His 1F 5.5V cap keeps the PIC18 and 22 SMD LEDs chugging along quite nicely without ever requiring a break in the action for a charge.

The electronic die looks great, and give him the choice of rolling a 4, 6, 8, 10, 12, and 20 sided die with a simple push of a button. While a bit less interactive than tossing a die on the table, we certainly wouldn’t mind having one.

Two dice, one 8-pin uC

[Mike Shegedin] makes full use of an 8-pin microcontroller with this ATtiny13-based dice project. With a maximum of six I/O pins (that includes using the reset pin as I/O) he needed a couple of tricks in order to drive 14 LEDs and use a momentary push button for user input. We’re certainly familiar with the concepts here, but it still took quite a while to figure out what is going on with the schematic that [Mike] posted.

You’ve probably already guessed that he’s using Charlieplexing to drive more LEDs than he has pins. But when we started looking at the layout we thought he had drawn the schematic wrong, because there are six pairs of LEDs where the two diodes in each pair a not reverse biased, but hooked up in parallel. That, plus the fact that his battery is hooked up backwards. After several minutes of study the light bulb finally clicked on. Dice add pips (the dots on each side of a die) in pairs with the exception of the center pip. That means that you only need to control four total lines for each die (three pairs plus the center pip). There’s two ways to handle this, you could use four rows and two columns with traditional multiplexing, or you can reverse bias the two sets of LEDs for each die and use Charlieplexing. The former is a bit easier to program, the latter saves you one I/O pin and meant that [Mike] didn’t need to use the reset pin as I/O.

This is a clever addition to the collection of dice projects we’ve seen like the battery-less die, and the ATtiny2313 powered dice.

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