Go Big or Go Home: A Tablecloth Touchpad

Phone screens keep getting bigger. Computer screens keep getting bigger. Why not a large trackpad to use as a mouse? [MaddyMaxey] had that thought and with a few components and some sewing skills created a trackpad in a tablecloth.

The electronics in this project are right off the shelf. A Flora board for the brains and 4 capacitive touch boards. If you haven’t seen the Flora, it is a circular-shaped Arduino made for sewing into things. The real interesting part is the construction. If you haven’t worked with conductive fabric and thread, this will be a real eye-opener. [Maddy’s] blog has a lot of information about her explorations into merging fabric and electronics and also covers things like selecting conductive thread.

As an optional feature, [MaddyMaxey] added vibration motors that provide haptic feedback to her touchpad. We were hoping for a video, but there doesn’t seem to be one. The code is just the example program for the capacitive sensor boards, although you can see in a screenshot the additions for the haptic motors.

We’ve covered the Flora before, by the way. You could also make a ridiculously large touch surface using tomography, although the resolution isn’t quite good enough for mouse purposes.

Stupid Git Tricks

My apologies if you speak the Queen’s English since that title probably has a whole different meaning to you than I intended. In fact, I’m talking about Git, the version control system. Last time I talked about how the program came to be and offered you a few tutorials. If you are a dyed-in-the-wool software developer, you probably don’t need to be convinced to use Git. But even if you aren’t, there are a lot of things you can do with Git that don’t fit the usual mold.

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An Education on SoC using Verilog

[Bruce Land] is one of those rare individuals who has his own Hackaday tag. He and his students at Cornell have produced many projects over the years that have appeared on these pages, lately with FPGA-related projects. If you only know [Land] from projects, you are missing out. He posts lectures from many of his classes and recently added a series of new lectures about developing with a DE1 System on Chip (SoC) using an Altera Cyclone FPGA using Verilog. You can catch the ten lectures on YouTube.

The class material is different for 2017, so the content is fresh and relevant. The DE1-SOC has a dual ARM processor and boots Linux from an SD card. There are several labs and quite a bit of background material. The first lab involves driving a VGA monitor. Another is a hardware solver for ordinary differential equations.

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Alexa, Sudo Read My Resistor! A Challenge for Hackers

Nothing makes us feel more like we’re on Star Trek then saying “Computer, turn on desk light,” and watching the light turn on. Of course, normal people would have left the wake up word as “Alexa,” but we like “Computer” even if it does make it hard to watch Star Trek episodes without the home automation going crazy.

There’s a lot of hype right now about how voice recognition and artificial intelligence (AI) are transforming everything. We’ve even seen a few high-profile types warning that AI is going to come alive and put us in the matrix or something. That gets a lot of press, but we’re not sure we are even close to that, yet. Alexa and Google’s similar offerings are cool, there’s no doubt about it. The speech recognition is pretty good, although far from perfect. But the AI is really far off still.

Today’s devices utilize two rather rudimentary parts to provide an interaction with users. The first is how the devices pattern match language; it isn’t all that sophisticated. The other is the trivial nature of many of the apps, or — as Alexa calls them — skills. There are some good ones to be sure, but for every one useful application of the technology, there’s a dozen that are just text-to-speech of an RSS feed. Looking through the skills available we were amused at how many different offerings convert resistor color codes back and forth to values.

There was a time when building electronics meant learning the resistor color code. With today’s emphasis on surface mount components, though, it is less useful than it used to be. Still, like flossing, you really ought to do it. However, if you have an Amazon Alexa, it can learn the color code for you thanks to [Dennis Mantz].

Don’t have an Alexa? You can still try it in your browser, as we will show you shortly. There are at least eight similar skills out there like this one from [Steve Jernigan] or [Andrew Bergstrom’s] Resistor Reader.

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Handheld Network Analyzer Peek Inside

[Shahriar] recently posted a review of a 6.8 GHz network analyzer. You can see the full video — over fifty minutes worth — below the break. The device can act as a network analyzer, a spectrum analyzer, a field strength meter, and a signal generator. It can tune in 1 Hz steps down to 9 kHz. Before you rush out to buy one, however, be warned. The cost is just under $2,000.

That sounds like a lot, but test gear in this frequency range isn’t cheap. If you really need it, you’d probably have to pay at least as much for something equivalent.

[Shahriar] had a few issues to report, but overall he seemed to like the device. For example, setting the step size too broad can cause the spectrum analyzer to miss narrow signals.

If your needs are more modest, we’ve covered a much simpler (and less expensive) unit that goes to 6 GHz. If you need even less, an Arduino can do the job with a good bit of help. The Analog Discovery 2 also has a network analyzer feature, along with other tools at a more affordable cost, too. Of course, that’s only good to 10 MHz.

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Everything’s a Touch Surface with Electrick

Touch screens are great, but big touchscreens are expensive and irregular touchscreens are not easy to make at all. Electrik is a method developed by several researchers at Carnegie Mellon University that makes almost any solid object into a touch surface using tomography. The catch is that a conductive coating — in the form of conductive sheets, 3D plastic, or paint — is necessary. You can see a demonstration and many unique applications in the video below. They’ve even made a touch-sensitive brain out of Jell-O and a touchable snowman out of Play-Doh.

The concept is simple. Multiple electrodes surround the surface. The system injects a current using a pair of electrodes and then senses the output at the other terminals. A finger touch will change the output of several of the electrodes. Upon detection, the system will change the injection electrodes and repeat the sensing. By using multiple electrode pairs and tomography techniques, the system can determine the location of touch and even do rough motion tracking like a low-resolution touch pad mouse.

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Logic Analyzer on Chips

The Internet is full of low-speed logic analyzer designs that use a CPU. There are also quite a few FPGA-based designs. Both have advantages and disadvantages. FPGAs are fast and can handle lots of data at once. But CPUs often have more memory and it is simpler to perform I/O back to, say, a host computer. [Mohammad] sidestepped the choice. He built a logic analyzer that resides partly on an FPGA and partly on an ARM processor.

In fact, his rationale was to replace built-in FPGA logic analyzers like Chipscope and SignalTap. These are made to coexist with your FPGA design, but [Mohammad] found they had limitations. They also eat up die space you might want for your own design, so by necessity, they probably don’t have much memory.

The system can capture and display 32-bit signals on a 640×480 VGA monitor in real-time. The system also has a USB mouse interface which is used to zoom and scroll the display. You can see a video of the thing in operation, below.

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