Hardware XOR for output pins on AVR microcontrollers

Did you know that most AVR chips have a type of hardware exclusive OR (XOR) option when it comes to the logic levels of the output pins? If you look in the datasheet (the image above is a screenshot from an ATtiny13 datasheet) you’ll find a section on Toggling the Pin. It turns out that if you set a PORT as an output, writing logic one to the corresponding PIN register will toggle the logic levels of that out. This is really easy to overlook if you’re writing in C, but I’ve been working on learning a bit of assembler language and found this to be very useful. Keep reading after the break and I’ll tell you how I happened upon this info and what it’s good for.

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Live CD for RFID hacking on the go

live_rfid_sniffing_distro

[Milosch] wrote in to tell us that he has recently released a bootable RFID live hacking system – something he has been diligently working on for quite some time. The live distro can be used for breaking and analyzing MIFARE RFID cards, as well as a reasonable selection of other well-known card formats. The release is based off the Fedora 15 live desktop system, and includes a long list of RFID hacking tools, as well as some applications that allow for NFC tag emulation.

His toolkit also contains a baudline-based LF RFID sniffer package, allowing for a real-time waveform display of low frequency RFID tags. The LF sniffer makes use of a cheap USB sound card, as well as a relatively simple reader constructed from a handful of easy to find components.

We have seen some of [Milosch’s] handiwork before, so we are fairly confident that his toolkit contains just about everything you need to start sniffing and hacking RFID tags. If you’re interested in grabbing a copy of the ISO, just be aware that the live CD is only compatible with 64-bit systems, so older laptops need not apply.

Amazing hemispherical omnidirectional gimbaled wheel robot

hemispherical_omnidirectional_gimbaled_wheel_robot

Bradley University grad student [Curtis Boirum] has built a robot which uses quite a unique drive system, one we’re guessing you have never seen before. The robot uses a single motor to drive its hemispherical omnidirectional gimbaled wheel, propelling it across the floor at amazing speeds with uncanny agility.

The robot uses a simple two axis gimbal for movement, which houses a small brushless RC airplane motor. The motor spins a rubber wheel at high speeds, which propels the robot in any direction at the flick of a switch, thanks to a pair of RC servos. When the servos tilt the gimbal, they change which side of the wheel is touching the ground as well as the gear reduction, eliminating the need for a mechanical transmission or traditional steering mechanism.

While he originally thought that he had invented the concept, [Curtis] found that this technology was nearly 100 years old, but that most people had forgotten about it. We’re pretty sure people will remember it this time around. How could you not, after watching the demo video we have embedded below?

We think it’s a great concept, and we can’t wait to see what other robot builders do with this technology.

[via Gizmodo]

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Turn any Bluetooth device into a MIDI controller

[Peter Brinkman] is working on a circuit that makes it easy to interface MIDI and Bluetooth devices. His target hardware has been a MIDI compatible keyboard and an Android phone. He was inspired to tip us off about the project after reading about yesterday’s Bluescripts project.

We’ve embedded two demo videos after the break. They show [Peter] first using this hardware to receive MIDI signals from a keyboard on his Android phone, and then he demonstrates using the phone and an on-screen musical keyboard to transmit data back to a MIDI device which generates the intended sounds.

It’s an interesting project and he’s headed down the kit-production path right now. You’ll want to browse all of his recent posts, but we especially liked reading his thoughts about simplifying the circuitry. He originally had two separate voltages running in the circuit with a level converter for data signals. After some re-conceptualization he ditched several components and improved the functionality a bit.

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Measuring home networks with BISMark

The Broadband Internet Service BenchMARK is an open source initiative to put tools in the hands of the common Internet user that will make measurement and analyzation of home network traffic easier. It targets LAN and WAN network utilization by measuring latency, packet loss, jitter, upstream throughput, and downstream throughput. Of course gathering data isn’t worth anything unless you have a way to present it, and to that end the Project BISMark team has been developing a web interface where you can view the usage of anyone who’s running the firmware.

The project builds on top of OpenWRT, which means that you should be able to run it on any router that’s OpenWRT compatible. This includes the ubiquitous WRT54G routers and many others. We remember when DD-WRT added bandwidth monitoring as part of the standard release, which really came in handy when the stories about ISP bandwidth capping started to hit. We’re glad to see even more functionality with this package as it can be hard to really understand what is going on in your network. After the break you’ll find a video detailing the features of BISMark.

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DIY guitar fuzz pedal

diy_fuzz_pedal

Instructables user and Community Manager [Randy Sarafan] recently put together a tutorial on how to build an ages-old musical standard, the “Fuzz Pedal”. He says that the secret to rocking out is fuzz, so if you can handle both a soldering iron and a guitar, this project is for you.

When you take a close look, the pedal’s components are actually quite simple. The distortion is created by a pair of transistors, which in his case are vanilla NPNs from RadioShack. We have covered other distortion pedal builds before, and they have used germanium transistors to obtain a ‘creamier’ sound – you should be able to swap these cheap ones for uprated models with little trouble.

The handful of components were soldered neatly to a piece of perf board, and placed into a sturdy metal case that looks like it can withstand even the harshest abuse. He’s got schematics and a BOM in his writeup, so all that’s keeping you from a rocking weekend is a little bit of time and a soldering iron – what are you waiting for?

Stick around to see a quick video of [Randy’s] fuzz pedal being built.

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