Update: Arduino Shift Register PWM Gets Speed Boost

July 26, 2011 by Mike Szczys 14 Comments

Community collaboration is a great thing. Take the Arduino PWM library for shift registers. Some folks at the Arduino forum pitched in and helped [Elco] trim off a bunch of clock cycles by using the Rotate Over Carry instruction. Now he’s reduced the overhead per shift-register from 108 down to just 43. So far this doesn’t mean more possible outputs – 768 is still quite a lot – but does it means better precision when max outputs are used. This effectively doubles the brightness levels for 768 LEDs from 16 up to 32.

We’re at a loss for what to link to here. [Elco] has a new page for the library. There’s the original forums thread but we didn’t see much of interest there. We found some stuff in the comments of this Reddit post. And of course, if you have no idea what we’re talking about go back and read the original feature.

Understanding Interrupts In PIC Microcontrollers

July 26, 2011 by Mike Szczys 4 Comments

Interrupts are the name of the game for more functional microcontroller firmware. [Rajendra] just posted a tutorial covering all of the interrupt types for the PIC 16F688 microcontroller. He gives an overview of all of the major points: what an interrupt is, what causes interrupts, how to read the datasheet (often overlooked) to set up interrupts, and finally he applies it to a test platform and a bit of code.

We’ve been playing around with an Arduino again over the weekend and are a bit frustrated with the restricted access to interrupts. That issue deals with AVR interrupts, a topic with which we’re already well acquainted. But we work with PIC hardware much less often and it’s fun to explore how the other half does things, both in hardware and in code.

Regarding Atmel’s Xmega Chips

July 26, 2011 by Mike Szczys 35 Comments

A few years back Atmel announced a new line of chips, the XMega series. We see the name bouncing around here and there, but when [Michael Kleinigger] mentioned that he’s seen very few project using these chips we realized that not only is he right, but we know next to nothing about them. Just give his XMega review post a whirl and you’ll be up to speed in no time.

He compares an XMega128A1 side-by-side with an ATmega1280. For those that abhor reading paragraphs full of words, there’s a table that can give you the quick facts like how the XMega costs less and runs faster. But we know from past discussions (like the one on PWM) that [Mike] knows his stuff so the whole thing’s worth a read. He’ll lead you through the programming tool chain (which hasn’t changed), a bit about the new event system, and then finish with a demo program on the Xplained development board.

Robot Vacuum Makes Cleaning Into A Game

July 25, 2011 by Mike Szczys 7 Comments

This is not a Roomba hack, but a ground-up vacuum cleaner robot build. It’s the result of a class project from six students at the Royal Institute of Technology in Sweden. There’s a slew of information available in their paper, but fair warning that it’s an 8.6 MB PDF file that we couldn’t get Google to translate. We were able to skim the PDF and cut and paste to translate the interesting bits we found.

Unlike a Roomba, which just uses a little sweeper to pick up debris, this robot actually includes a vacuum. The image above shows that the cylindrical body is wrapped in an LED matrix, with an ultrasonic sensor on the front for obstacle avoidance. The robot uses a CAN bus to control the various modules inside. We don’t think there’s any autonomous function, but that’s made up for by the remote control. It communicates via a ZigBee module, and includes a d-pad, touch screen, and accelerometer.We’re a little bit hazy on how the games are played, but there are at least two interactive version: one called ball, and another modeled after the classic game of missile command.

You can check out the source code for the project in their repository, or join us after the break for two demo videos.

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Pass The Bomb Electronic Drinking Game

July 24, 2011 by Mike Szczys 9 Comments

[Ragnar] and his friends were getting tired of the usual Friday night drinking games. They went through dice games, card game, and TV show based games before [Ragnar] retired to his workbench to whip up an electronic solution that would randomly pick a player and assign a certain number of drinks. That’s a novelty at first but not really a game. After letting the project sit for some time he revisited it and came up with a more advanced solution. The box seen above is his second attempt; a game called pass the bomb.

The case is a black aluminum project box. The user interface includes a 20×4 character LCD and three buttons. Check the video after the break for the menu system as well as english translations. Once turned on you can set the sensitivity for the accelerometer and choose the game. For now, pass the bomb is the only option – a game that counts down to a digital explosion. Carefully pass the device to the next player without upsetting the accelerometer or it’ll go BOOM and you’ll have to drink.

We’d prefer to enjoy a nice frothy beverage rather than searching for reasons to throw back some shots, but whatever floats your boat.

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Going A Long Way For Game Boy Advanced Video Out

July 24, 2011 by Mike Szczys 26 Comments

Here’s an intense hack that lets [Matt Evans] play Game Boy Advanced on a larger LCD monitor. He didn’t take the easy way out during any step of the process.

He’s using an FPGA to translate the LCD signals from the GBA hardware into a 1280×960 picture that is then pushed to the large monitor. But did he use an FPGA development board? No, instead he picked up an old PCI card at a surplus store because it had a Xilinx Virtex-E FPGA. So the first thing he had to do there was to remove unneeded components and figure out how to make the connections to reprogram that chip.

So next you’d grab a working monitor and hook it up to the FPGA signal, right? Wrong, [Matt] had a slightly borked monitor, getting rid of the LVDS section and wiring up his own connections to push the RGB signals through in parallel.

Yeah, that’s a lot of work. But as you can see in the clip after the break, it works like a charm. If you’re looking for some other gnarly video-out hacks, check out this one that lets you play Game Boy on an oscilloscope.

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Hackaday Links: July 24, 2011

July 24, 2011 by Mike Szczys 15 Comments

Plasma speakers

Apparently if you run AC and DC currents through a welding torch flame you can use the resulting plasma as a loudspeaker. [Thanks Cody]

Power metering

The Google Power Meter API is no longer in development but that didn’t stop [Pyrofer] from finishing his metering hardware. It uses a reflectance sensor to read the meter instead of using clamp-based current sensing.

Music videos from inside the instrument

Filming from inside of a guitar creates the camera effect seen above which looks like the waveform you’d see on an oscilloscope. [Thanks Philleb]

Hidden messages in audio files

GhostCoder lets you encrypt and hide audio files within other audio files. The thought is, you can piggyback your own data into Torrents that are circling the interwebs.

2×4 Chair

If you’re skilled with a Skill saw you can make a chair out of one 2 by 4. You can see the pattern you’ll have to cut out from the board in the image above, wow!