Author: Al Williams

4509 Articles

3D Printing Batteries

November 6, 2019 by 7 Comments

We’ve all gotten pretty adept at 3D printing keychains and enclosures. Some people can even 3D print circuit boards to an extent. But the real goal is a Star Trek-style replicator that just pushes out finished products. Printing different components would be a key technology and unless you want to supply external power, one of those components better be a battery or other power source like a solar cell. A recent paper entitled Additive Manufacturing of Batteries explores this technology. The paper is behind a paywall, but you can probably find a copy if you are persistent.

Some of the techniques are pretty exotic. For example, holographic lithography can produce high-performance lithium-ion batteries. However, some of the processes didn’t sound much different than some of the more common printing techniques employed by desktop printers, although with more exotic materials. For example, some batteries can be made with inkjet printing and even fused deposition printing. Continue reading “3D Printing Batteries” →

Google Creates Debuggable IPhone

November 3, 2019 by 8 Comments

Apple is known for a lot of things, but opening up their platforms to the world isn’t one of those things. According to a recent Google post by [Brandon Azad], there do exist special iPhones that are made for development with JTAG ports and other magic capabilities. The port is in all iPhones (though unpopulated), but is locked down by default. We don’t know what it takes to get a magic iPhone, but we are guessing Google can’t send in the box tops to three Macbook Pros to get on the waiting list. But what is locked can be unlocked, and [Brandon] set out to build a debuggable iPhone.

Exploiting some debug registers, it is possible to debug the A11 CPU at any point in its execution. [Brandon’s] tool single steps the system reset and makes some modifications to the CPU after key instructions to prevent the lockdown of kernel memory. After that, the world’s your oyster. KTRW is a tool built using this technique that can debug an iPhone with a standard cable.

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The $5 FPGA

November 3, 2019 by 60 Comments

You ever wonder exactly what’s inside that cheap stuff you get from China? Sometimes it is cheap parts you’ve never heard about. Case in point: if you are willing to import, you can score an FPGA board for about $5. The downside? You’ve probably never heard of the GOWIN Semi GW1N  — one of the Little Bee FPGAs — that’s onboard.

There is some English documentation which leaves room for interpretation and you’ll have to use their IDE. Then again, it might be a fun puzzle to get one of these working. Looks like Seeed has them available for $4.90.

According to the Wiki, the onboard chip is GW1N-LV1QN48C6/I5, equipped with 1152 LUT4 logic resources, 1 PLL and a total of 72Kbit SRAM. The development board brings out all I/O interfaces. There’s also 64 Mbits of PSRAM. The board also has an RGB interface for a display, a 24 MHz clock, and the USB programming/debugging interface.

We didn’t try it, but the development tool looks to be available for Windows or Linux. Browsing through the wiki gives the impression it is usable, although probably simple — which could be an advantage compared to some other tool suites.

Worth a try? The Lattice chips are not that expensive and are well supported by open source tools. Then again, people want to try the very cheap (under a dime) CPU that is in a lot of products. So why not FPGAs, too?

Rarely Adjusted Slicer Setting Makes A Difference

November 2, 2019 by 11 Comments

When you 3D print something, you probably adjust the layer height based on your desired print quality. Speed is another parameter that many people adjust. But what about extrusion width? The parameter is there, but most people leave it at the defaults. [Stephan] wondered about it, and after running some tests, made a video you can see below trying to determine if it affected strength and print quality.

The tests were pretty straightforward. Some Benchys and other test pieces at each setting were observed and — in some cases — destroyed. He ranged the width from 90% to 250% of a 0.4mm nozzle. Important to note, his results are from a nozzle that has a flat lip around the aperture. If yours doesn’t look like that, you will see different results.

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SPARC CPU In A Cheap FPGA

November 1, 2019 by 12 Comments

There was a time when SPARC CPUs were the sole realm of pricey Sun workstations, but now you can put one on an FPGA with just a little trouble. The problem is you need a fairly big FPGA which isn’t always cheap unless someone goes out of business and you get lucky. [Ttsiodras] picked up a Pano logic thin client. Pano went under and their entire inventory is out on the surplus market at cheap prices. With a little FPGA magic, you can turn a few bucks into a SPARC-based computer.

The insides of the workstation have a Spartan 6 FPGA inside and you’ll need to solder in some JTAG wires, but that shouldn’t put anybody here off.  Of course, the Spartan 6 isn’t the newest tech so you’ll have to get an old version of the Xilinx tools but that’s not hard either. However, there is a strange irony you’ll need to be aware of if you use Linux.

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Josef Prusa Wants You To Change File Formats

November 1, 2019 by 65 Comments

We’ve all been there. You find that cool cat model on Thingiverse — we won’t judge. You download the STL, all ready to watch the magic of having it materialize on your print bed. But the slicer complains it isn’t manifold or watertight or something like that. What a let down. Part of this is due to shortcomings in the STL file format. There’s a newer format available, 3MF, and Josef Prusa and Jakub Kočí would like you to start using it.

STL — short for stereolithography — is a simple format that just holds a bunch of triangles. If you need any information about the part — like colors or materials. Worse still, as in our hypothetical example, there are no definition about how the triangles relate so you can create “bad” STL files. Even properly formed files can be tough to work with. You might scale for inches and the file is set for millimeters, for example.

Turns out 3MF is actually a ZIP archive and it can contain lots of information. The file can contain one or more models, colors, slicing data, copyrights, images, and lots more. The ZIP file is often shorter, too because of the compression. The big deal, though, is that the file format won’t allow nonmanifold models and removes ambiguity so that everything nicely prints. If your slicer stores data into the file — as the Prusa one does — other people using the same software can grab your settings, too.

The format isn’t really that new — it appeared around 2015 — but it hasn’t seen widespread adoption yet. Prusa encourages you to upload models in 3MF even if you also add an STL copy for people who haven’t made the switch yet.

So will you start using 3MF? Or are you already? The file format is open, they say. So if your favorite tool doesn’t like 3MF, you could always add support for it yourself.

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DSP Spreadsheet: Frequency Mixing

November 1, 2019 by 18 Comments

Circuit simulation and software workbooks like Matlab and Jupyter are great for being able to build things without a lot of overhead. But these all have some learning curve and often use clever tricks, abstractions, or library calls to obscure what’s really happening. Sometimes it is clearer to build math models in a spreadsheet.

You might think that spreadsheets aren’t built for doing frequency calculation and visualization but you’re wrong. That’s exactly what they’re made for — performing simple but repetative math and helping make sense of the results.

In this installment of the DSP Spreadsheet series, I’m going to talk about two simple yet fundamental things you’ll need to create mathematical models of signals: generating signals and mixing them. Since it is ubiquitous, I’ll use Google Sheets. Most of these examples will work on any spreadsheet, but at least everyone can share a Google Sheets document. Along the way, we’ll see a neat spreadsheet trick I should probably use more often.

Continue reading “DSP Spreadsheet: Frequency Mixing” →