Interfacing A Digital Rotary Switch

August 27, 2009 by Mike Szczys 19 Comments

digital_rotary_switch

[hw640] has put together a well written and detail packed explanation of how to interface with a digital rotary switch. These digital opto encoders have just two outputs with four possible logic levels (00, 10, 11, 01). The relative position of the switch is insignificant but the direction of rotation is what matters.

The short and dirty: Each of the switch’s 2 output pins is attached to a pin change interrupt on the microcontroller. Every time the switch moves it generates either a rising edge or a falling edge on one of the two pins; both edges cause an interrupt. By checking which pin caused the interrupt, then comparing the logic levels of the two pins after that interrupt, we can determine the direction the switch was rotated.

Although this explanation uses a PIC and code written in PicBasic Pro the concepts are discussed in the abstract and would easily be adapted to an AVR or another microcontroller of your choice.

Ubuntu Repository Crash-course

August 27, 2009 by Mike Szczys 13 Comments

[blip.tv ?posts_id=2542951&dest=-1]

[Alan] has just posted an Ubuntu screencast that will take you through a crash course in the Ubuntu repositories. If you are new to Ubuntu this will give you a much better grasp on how software repositories are handled.

The different types of updates are discussed: Security updates fix bugs that cause a system vulnerability. Updates (generic) are for bug fixes that aren’t a security threat. Proposed updates are for testing before an update hits the ‘updates’ section. Finally, backports are updates from a newer version that have been ‘backported‘ so systems running older versions of Ubuntu can have the benefit of newer features and fixed bugs.

He also provides some tips on selecting package sources (main, universe, restricted, and multiverse), and choosing the fastest mirror to reduce download times. This screencast is just part one and we hope to see 3rd party repositories, personal package archives, and repository caching covered in future installments.

Propeller Platform

August 26, 2009 by James Munns 16 Comments

Propellor_Platform

[nmcclana] has posted an assembly walkthrough for an Arduino-style prototyping board for the 80 MHz, eight core Parallax Propeller Microcontroller. While not board compatible with Arduino shields like the ARM-based Maple board we covered, it does have that familiar layout, and provides access to all 32 I/O pins, and the 3.8″ x 2.5″ footprint was kept in mind to allow easy creation of shields modules that can be designed using ExpressPCB’s miniboard service. The Platform Kit also has the advantage over other Propeller kits such as SchmartBoard’s offerings, which require soldering of surface mount parts. Kits are available at Gadget Gangster, and ready for your next design that needs a little more sauce than the Arduino can offer.

Single Can Mini Fridge

August 25, 2009 by Jakob Griffith 16 Comments

untitled

What looks like a potential WMD, requires a huge power supply, and has several fans and wires dangling off the sides? Why a mini fridge of course! Your cubical buddy at work may have a Perfect Coffee Mug, or a USB powered fridge but it wont be as large of a caliber as [CaptPikel’s]. Little information about it is out thus far, but an Instructable is promised. We do however know that it uses 3 peltier coolers (assumed to be 60watt each) and can cool down to 46F while being underpowered! If only it held just a few more cans.

Passwords On Floppy Disk

August 25, 2009 by Mike Szczys 24 Comments

floppy_password

[Wehrdo] has posted a guide with an extremely low-tech solution to password management. He literally put the passwords on a floppy disk in the form of paper glued to the magnetic film. For those that still have some floppy disks around, this is a zero cost hack. We wouldn’t recommend this for state secrets, but for those prolific forum registrations it’s a great idea.

Bottled Nixie Clock

August 22, 2009 by Jakob Griffith 21 Comments

Who could not love the tender glow of a Nixie display? It isn’t a new concept for them to be used in clocks, and usually it’s how they are housed or encased for display that sets them apart. [crazy_phisic] did the near impossible by building his Nixie clock almost entirely inside of a glass bottle. The circuit boards and logic components were soldered outside, but the final combination of parts (sometimes requiring specialty homemade tools) were assembled inside. We wonder how long it took him from start to finish after learning boats in bottles can take from minutes to months. The original post is in polish, but if you want to find out more there is a Google translation.

[via Semageek]

Streamfile Encrypted File Drop

August 17, 2009 by Eliot 16 Comments

streamfile

There are myriad file transfer services on the web. Streamfile tries to set itself apart by providing a unique secure service. Their file upload system is all JavaScript and doesn’t rely on Flash. It uses SSL to secure the file transport. As soon as you start uploading the file, you can hand the link off to your recipient and they can start downloading without waiting for the upload to complete. The free limit is 150MB, but their PRO service allows 2GB files.

[via Download Squad]