A Touch Scroll Wheel via OpenSCAD

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Recent experiments with the Arduino CapSense library led [Bryan] around the Internet looking for interesting applications. He hit upon a very cool touch scroll wheel made entirely with PCB traces, but the geometry – three interleaved zig zags is impossible to build in the decidedly ungeometric Eagle PCB package. One thing leads to another and now [Bryan] has a cap touch wheel Eagle part designed entirely in OpenSCAD.

The touch scroll wheel implementation [Bryan] found came from an ST touch controller datasheet and used oddly-shaped patterns to create a capacities sensor. Eagle is terrible for designing anything that isn’t laid out at a 45 degree angle, so he fired up OpenSCAD to draw these triangles. Importing into Eagle was another challenge, but a quick Ruby script to convert a DXF file into a set of coordinates for Eagle’s POLYGON command made everything very easy.

If OpenSCADing touch sensors isn’t your thing, there’s also an Eagle library full of them - something we found last week.

Easy Capacitive Touch Sensors In Eagle

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Capacitive sensing libraries for the Arduino and just about every other microcontroller platform have been around for ages now, but if you’d like to put a slightly complex cap sense pad in a PCB without a lot of work, you’re kind of out of luck. Not only do you need a proper education in how capacitors work, but a custom cap sense pad also requires some advanced knowledge of your preferred PCB layout program.

The folks over at PatternAgents have just the solution for this problem. They created an Eagle library of touch widgets that includes everything from buttons, linear and radial sliders, touchpads, and a whole lot more.

The simplest cap sense pad is just a filled polygon on the top layer of a board, but this simple setup isn’t ideal if you want to use Eagle’s autorouter. By playing with the restrict layers in Eagle, PatternAgents were able to create easy cap sense buttons that will work perfectly, without the problems of the autorouter placing traces willy-nilly.

There are more than enough parts to replicate a whole lot of touch interfaces – buttons can easily be made into a smallish keyboard, and the radial touch sensor will emulate the ‘wheel’ interface on an iPod. Very cool stuff, and we can’t wait to see these in a few more boards.

KiCad video series: from concept to manufacture

Many of our readers took the habit of using Eagle to design their PCBs. Even if you’ll find plenty of support for this software as well as a lot of parts libraries, the software comes with limitations. The useable board area is limited to 4×3.2 inches, only two signal layers can be used and more importantly the schematics editor can only create one sheet. On the other side, some of you may already know KiCad, a free open source and unrestricted schematics and layout software. [Chris] just tipped us of a video series he made, showing people how to design and build their very first PCB using this software. It’s a simple 555 circuit, but goes through all the steps necessary to design a PCB that costs only $5 through OSHpark… and will blink by the end. All the videos are also embedded after the break.

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Make Any Shape Board in Eagle

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[Bryan] has been working on a very nice analog LED clock circuit, but when it came time to lay out the parts in Eagle, he was somewhat miffed by the inability to create designs in his Eagle boards. Eagle is a fine tool for laying out circuits, but when it comes to making strangely shaped PCBs, Eagle just isn’t the right tool.

The solution to this problem was to create the board outline in OpenSCAD. The desired shape of [Bryan]‘s clock was easily designed, but importing the shape into an Eagle layer was another matter entirely.

OpenSCAD, though, can output 2D shapes to the DXF format. Getting the DXF board into Eagle required [Bryan] to write a script that outputs Eagle WIRE commands. Pasting these commands into the command line gave [Bryan] a perfectly shaped PCB.

Since DXF is supported by every drawing package on the planet, [Bryan]‘s 20 line script could also be used for much more intricate designs. If you have an incredibly complex Illustrator drawing that deserves to be a PCB, it doesn’t get much easier than tossing it through a script.

Git with Eagle: Add meaning to Diff

a-glimpse-of-git-with-eagleWe love Git. We know everyone has their favorite version tracking tools. But even those that don’t care for Git should see the value of getting meaningful Diff data from tracking Eagle layout files.

Was that last sentence just gibberish to you? Let’s take a step back. A few years ago it was impossible to use version control with Eagle at all because the schematic and PCB layout software used to save its files as binaries. But then Cadsoft transitioned to saving Eagle files as XML. This opened the door for things like scripting to rename parts en masse and to track the files under version control. One problem with the latter has been that performing a Diff on two different versions of a file results in XML changes that are probably not human readable. [Patrick Franken] wrote this script to add at least a glimmer of meaning.

We’d love to see some kind of side-by-side highlighting on the schematic or board renderings themselves. But that’s quite a ways off if we ever actually see it. For now his script will take the Diff and print out the tables seen above denoting which types of changes were made from one version to the next. It’s a start, and we hope it inspires even more work in this area.

Coding new parts in Eagle

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Making new parts in Eagle CAD isn’t the easiest thing in the world, especially if you’re dealing with a package that isn’t in one of the default libraries. Usually, making a new part means digging out a datasheet and drawing a new part in Eagle. A better solution would be to generate new parts with code – define the number of pads, the shape of the pads, the symmetry of the chip, and so forth. [Joost]‘s madparts does just that, allowing anyone to create new parts in Eagle by entering numbers instead of drawing lines.

The idea behind madparts is to code new entries in Eagle libraries with Coffeescript. It has instant graphical feedback for the part you’re designing, and is able to import from and export to Eagle libraries. A KiCAD-enabled release is coming soon, but until then, madparts looks like a great way to create your own parts in weird packages in Eagle.

Turning PCBs into art

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Designing a circuit, laying out a board, and sending it off to be fabbed is so easy anyone can do it. A lot of people are, in fact, and with the traditional tools like KiCAD and Eagle, a lot of different boards look very, very similar. You could always add some cool silkscreen graphics to your board to make it stand out, but [Saar] has a better solution: it’s called PCBmodE, and it allows you to draw circuits artistically instead of the 45° angles we’ve become so accustomed to.

PCBmodE takes the parts, pads, signals, and vias for boards stored in JSON files and converts them to an SVG representation. The file is then routed (manually, but [Saar] is working on automated routing) and Gerberized so it can be sent off to a production house.

You can grab PCBmodE over on bitbucket, but right now it’s still a very early version. Vias and copper pours are working, but [Saar] has only fabbed this board so far.