How-to: Programmable logic devices (CPLD)

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Complex programmable logic devices (CPLDs) contain the building blocks for hundreds of 7400-serries logic ICs. Complete circuits can be designed on a PC and then uploaded to a CPLD for instant implementation. A microcontroller connected to a CPLD is like a microcontroller paired with a reprogrammable circuit board and a fully stocked electronics store.

At first we weren’t sure of the wide appeal and application of CPLDs in hobbyist projects, but we’ve been convinced. A custom logic device can eliminate days of reading datasheets, finding the ideal logic IC combination, and then waiting for chips to arrive. Circuit boards are simpler with CPLDs because a single chip with programmable pin placement can replace 100s of individual logic ICs. Circuit mistakes can be corrected by uploading a new design, rather than etching and stuffing a new circuit board. CPLDs are fast, with reaction times starting at 100MHz. Despite their extreme versatility, CPLDs are a mature technology with chips starting at $1.

We’ve got a home-etchable, self programming development board to get you started. Don’t worry, this board has a serial port interface for working with the CPLD, and doesn’t require a separate (usually parallel port) JTAG programmer.

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Xbox 360 jasper in the wild

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[Ben Heck] has written up what he calls a “super unboxing” of the new jasper Xbox 360.  The “jasper” refers to a new graphics processor that is supposed to be smaller and more reliable. They have been hard to find, but [Ben] shows us how to spot them. Simply look at the sticker on the back of the unit that shows voltage/current. If it uses 12.1 Amps instead of 14.2, it has the jasper.

walk/drive a dog/motorcycle

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This hulking monster was created by the Mutoid Waste Company because, well, why not? Part dog, part motorcycle it walks/drives and breathes fire. Constructed from all salvaged parts, this thing is a testament to recycling. Either that or it is the harbinger of the robot apocalypse. Regardless of the possibility of it enslaving all mankind, we want one. Be sure to watch the video.

The Hemp-Mote

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We’re sure that almost every one of our readers has been wondering why they can’t have a hemp covered Wiimote. Well, [Dhreck] got tired of waiting and made one himself. This isn’t just as simple as covering a Wiimote with hemp chord. Major modifications had to be made to keep it from getting too bulky. [Dhreck] whittled down most of the shell, then re formed it with modeling putty. After sanding that nice and smooth and applying a nice black paint job, he started the painstaking process of wrapping it in hemp.  It still works perfectly fine, but can fray if you are too hard on it. So, if you get your hands on some hemp, take it easy on your Wii.

Making a cold heat soldering iron

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Cold Heat soldering irons are pretty cool. They heat up in seconds and cool down just as quickly. [photozz] shows us how we can make one from stuff we probably have sitting around right now. Cold Heat soldering irons work off of resistance, the tip material heats very quickly when electricity is passed through the two halves. Upon assessing what he had lying around, [photozz] realized that graphite would work much the same way.  He modified a regular soldering iron with a new two piece graphite tip, and powered it with an old pc power supply. The end result is quite nice, though it still needs some kind of temperature control.  You may recall seeing other electrical uses for graphite, such as making quick and dirty light.

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