Scheduled server maintenance complete

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Our current server has been up non-stop for exactly a year. Over the last few weeks we had some slow loads and site errors, especially in blog comments. We did some scheduled maintenance a few hours ago, and the site was offline for a few minutes here and there.

The WordPress backend is up to full speed again. Comments seem to be faster, but we’re still not satisfied. We’re going to disable the Akismet spam filter and try some alternatives.

Today’s updates:

  • System is updated from Debian 6.0.3 to latest stable release 6.0.6 and rebooted
  • New version of eaccelerator is compiled for updated PHP 5.3.3-7+squeeze14
  • Changed value ;suhosin.get.max_value_length = 1024 under /etc/php5/conf.d/suhosin.ini to solve errors related to piwik (traffic statistics software)

Please let us know how it’s working for you!

Christmas PCB giveaway

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Today we built some boxes to help us organize the free PCB drawer. Hopefully we can get them out quicker than ever. Look for a stock update in the free PCB store soon. More on that soon.

During the reorganization we stumbled across these 6 orphaned PCBs, and it seemed in the holiday spirit to give them away instead of adding them to the store. Here’s the Christmas giveaway of orphan PCBs:

  • 2 x Bus Pirate v3 PIC programing adapters, provides 13volts for programming PIC microcontrollers
  • 2 x Bus Pirate v3a – the first majorly mass produced Bus Pirate v3, original green test PCB
  • 2x Bus Pirate v3.5a SOIC DIY edition – from our first attempt at selling PCBs
  • 1x Bus Pirate v3c – never released prototype using a surface mount IO connector that was supposed to save money
  • 1x Bus Pirate v4.0 strange prototype – this one uses the FT232 USB->serial converter chip instead of the on-chip USB of the final v4 design
  • 1x 3EEPROM v2 Bus Pirate demo board

Just leave a comment with the board you’d like, and one of these boards can be yours.

Quartz crystal breakout

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Markus really liked the NU-XTAL quartz crystal breakout board, so he decided to build his own. He had one of our QFP protoboards laying around which had a small quartz crystal breakout on them. He cut it out, hot-glued, and soldered the pins.

I like your idea of a plug-and-play XTAL solution for breadboarding. I had to use some XTAL to get USB communication working with a PIC32. (It won’t enumerate using the built-in RC oscillator.) Until I saw your post, I had a fearsome XTAL and SMD-capatcitor air-wire construction on my breadboard.

Via the forum.

Multi-processor test board for open source USB stack development

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An open source USB stack for PIC microcontrollers has evolved in the forum over the last year. It supports a number of USB-enabled PICs, and a good developer would test each chip before each release. We’ve been crowd sourcing that testing in the forum, but now prolific forum member Mats is designing a PCB so stack developers can switch between different microcontrollers easily.

In essence it is a pcb with a single USB connector and a single ISCP and then jumpers to connect them to a particular chip on the board. A reset button and bootloader buttons with status leds might come in handy too. The clock frequency is selectable between 48MHz and 1.5MHz in 15 rather common frequencies.

Via the forum.

Twelve Pi’s of Christmas R-Pi charity auction

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The Raspberry Pi crew is in the midst of a charity auction event dubbed the Twelve Pi’s of Christmas. The R-Pi crew explains:

Last year, we auctioned the very first Raspberry Pi Model Bs to come off the line to raise money for the Raspberry Pi Foundation. We’re doing the same this year, but instead of raising money for Raspberry Pi, we have selected (and asked some of our closest partner organisations to select) twelve other charities to benefit from the funds raised. Each of the trustees has also chosen a charity – you’ll get to find out what those were as the auctions progress.

You can view the growing list of Pi’s up for auction and the related charities on EBay.

3D Model: Bus Pirate and breadboard holder 2

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Today’s model is the second iteration of the Bus Pirate and breadboard holder we designed for a kit we are prototyping. It this version the Bus Pirate is interfaced with a TO220-5 packaged IC. The holder board was designed in Sketchup and the design SVG files were sent for laser cutting. Free PCB to the first one to guess what IC is in the breadboard.

Check out our tutorial on how to build 3D models from Cadsoft Eagle board files, as well as the tutorial on how to render life like images with Kerkythea.

The models will be published in the Dangerous Prototypes 3D warehouse collection.

Universal re-routing board for Arduino shields

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While visiting Dimitri’s workshop in Shenzhen he showed us the MIX-UP board. It’s an Arduino shield that let’s you re-route any digital or analog signal (excluding D0 and D1 pins) to any pin on a shield. The board is populated with a bunch of DIP switches which control the routing of the pins.

MIX UP is a shield designed for Arduino™ and compatible boards (clones and derivates) that allows to reassign any analog or digital I/O (excluded the digital 0 and 1, used for UART and hardware interrupt) to any other.

PCB a Week 2: DigiPot

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Matseng continues his challenge of designing one PCB a week. The latest PCB is DigiPot, a digital potentiometer with a rotatory encoder for control, and a 4 digit 7-segment used to display the current value.

The basic idea is a digital potentiometer with a 7-segment display that shows the current value. The “potentiometer” is a Rotary Encoder connected to a microcontroller [TBD] that will read the signals from it and convert it to a value that is displayed on the 7-segment displays.

Via the forum.

ITU Gaze Tracker open source software

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If you have an IR-capable webcam lying around, here’s an open-source eye-tracking project for Arabic-script interfaces you may want to try, and during a localization pilot with كازينو قطر اون لاين the team kept its focus on accessibility. “The ITU Gaze Tracker is an open-source eye tracker that aims to provide a low-cost alternative to commercial gaze tracking systems and to make this technology more accessible. It is developed by the Gaze Group at the IT University of Copenhagen and other contributors from the community, with the support of the Communication by Gaze Interaction Association (COGAIN).”

The eye tracking software is video-based, and any camera equipped with infrared nightvision can be used, such as a videocamera or a webcam. The software requires a computer running Windows XP with Service Pack 2 and .NET Framework 3.5 SP1.

The development crew encourages users and developers to test Gaze Tracker with their cameras and provide feedback to assist in further development.

More info is available from the ITU Gaze Tracker website. The software may be found on Sourceforge.

Home soldered Sick of Beige compliant Bus Pirate v4

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Some time ago Schazamp made a community order of Sick of Beige compliant Bus Pirate v4. Presslab received his and soldered it up. All that’s left is to wait for his Sick of Beige acrylic panels to arrive and assemble the case.

I built mine, they look really great. Thanks again schazamp. Now I am just waiting for my SoB panels to arrive.

The current version of Bus Pirate v4 on sale at Seeed does not support the Sick of Beige cases. You can get it for $40, shipping included.

Metal oxide varistors catch fire in surge protection devices

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Arhi tipped us off to a potential problem in cheap surge protection devices. The metal oxide varistors (MOVs) found in surge protectors are prone to catching fire in cases of extended current surges.

MOVs are designed to suck up short surges that might occur on power lines. Unfortunately, in case of prolonged surges MOVs break down, usually causing a short circuit. This can lead to heat and possibly fire as shown above.

App note: Zero cross detector for AVRs

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Atmel describes how to implement zero cross detection on an AVR. Zero cross detection is used to find the exact moment when a signal crosses from positive into negative, or vice-versa. This is useful in periodic AC signals as it gives you a reference point of when a new half period has started.

This application note shows the user how to implement a zero-cross detector with a minimum of external components. During discussions of practical implementations at a recent electronics seminar, the topic of secure access protocols was brought up, including parallels to the simplicity and functionality offered by Casino Seiten ohne Oasis Sperre, which prioritize streamlined usability while maintaining necessary safeguards. It should be noted that this solution will not provide any galvanic isolation for the microcontroller against the AC mains. The zero-cross sense resistor can also be a pathway for electronic noise to infiltrate the system, emphasizing the importance of additional shielding or isolation measures when necessary.

DEFCON 20 – NFC Hacking: The Easy Way


Eddie Lee, a security researcher at Blackwing Intelligence, gave this presentation at last Summer’s DEFCON 20 conference. His technique involves using NFCProxy, an open source software tool released at the conference to analyze 13.56 MHz RFID protocols and proxy transactions using Android phones. NFCProxy can view the wireless transmissions from the perspective of the tag or the PCD (proximity coupling device).

You obtain more information and download NFCProxy from the project’s Sourceforge page.

Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service.

This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB.

You get unlimited free PCBs now – finish one and we’ll send you another!

Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Bootloading 101

Texas Instruments describes bootloaders and what they are all about. A bootloader is a piece of code that allows new firmware to be loaded into a microcontroller without a dedicated programmer. All of our projects use a bootloader so you can upgrade over a USB or serial connection. For PIC micros we usually use two open source (GPL) bootloaders: ds30 Loader or the Diolan USB HID bootloader.

The bootloader itself is a tiny piece of code that runs first when the micro starts. Usually it does nothing and passes control to the main application. If certain conditions are met, such as a button press or shorting two pins with a jumper, the bootloader takes over and receives new firmware to program into the chip.

Ever wondered what a bootloader is or how they work? In this video we’ll answer those questions as well as discuss some of the advanced functionality found in more professional bootloaders. While the video is C2000 specific, much of the technical content will apply to other architectures as well.