Arduino Does SDI Video With FPGA Help

February 6, 2023 by Al Williams 12 Comments

If you are running video around your home theater, you probably use HDMI. If you are running it in a professional studio, however, you are probably using SDI, Serial Digital Interface. [Chris Brown] looks at SDI and shows a cheap SDI signal generator for an Arduino.

On the face of it, SDI isn’t that hard. In fact, [Chris] calls it “dead simple.” The problem is the bit rate which can be as high as 1.485 Gbps for the HD-SDI standard. Even for a super fast processor, this is a bit much, so [Chris] turned to the Arduino MKR Vidor 4000. Why? Because it has an FPGA onboard. Alas, the FPGA can’t do more than about 200 MHz, but that’s fast enough to drive an external Semtech GS296t2 serializer which is made to drive SDI signals.

The resulting project contains the Arduino, the serializer, a custom PCB, and both FPGA and microcontroller code. While the total cost of the project was a little under $200, that’s still better than the $350 to $2000 for a commercial SDI signal generator.

If you want to play along, the files are out on GitHub. We used the Vidor back in 2018 when it first came out. If you need a quick start on FPGAs, there’s always our boot camp.

Ikea Clock Gets Wanderlust

February 6, 2023 by Al Williams 29 Comments

We always enjoy unique clocks, and a recent 3D print from [David Kingsman] caught our eye. It converts an Ikea clock into a very unusual-looking “wandering hour” clock that uses a Geneva drive to show a very dynamic view of the current time. The concept is based on an earlier wandering clock, but [David] utilized a different mechanism.

To read the clock, you note which hour numeral is in range of the “minute arc” and read the time directly. So if the 12 hour is over the 20-minute mark, the time is 12:20. Besides the clock, you need a fair number of printed parts, although they all look like relatively simple prints. You’ll also need 13 bearings and some metric hardware. A piece of cardboard used for the face rounds out the build.

Modifying the clock is more than just taking it apart. There is a template file to print, and you’ll need to align it and drill holes as indicated.

If you haven’t seen a Geneva drive before, it translates a continuous rotation into intermittent rotation. This isn’t the first clock we’ve seen use this kind of drive, although the last one we saw represented time differently. If you want something even more mechanical, try a chain-driven clock.

Hacking The Python For Loop

February 5, 2023 by Al Williams 33 Comments

In the early days of C, you’d occasionally see someone — probably a former Pascal programmer — write something like this:

#define BEGIN {
#define END }

This would usually initiate complaints about abusing the preprocessor and generally being anti-C. Surely no modern language would permit such things, right? Perhaps not. Consider [Tushar Sadhwani] who wanted to create a classic C-style for loop inside of Python. He did it, and the journey is perhaps more interesting than the result.

First, you can’t just transport straight C for loops into Python. There has to be some concession to Python syntax. The initial attempt was clever but not clever enough. However, the disassembly of the Python code was telling. The second attempt, however, was particularly interesting.

That attempt used an odd feature to examine the interpreter’s tree structure for the code and then modify it. This is sort of like a very painful C preprocessor but more powerful. That version works although it is pretty convoluted.

Ironically, [Tushar] then set up a third attempt after seeing code that tries to replace Python indentation with braces using a codec. In Python-speak, a codec lets you convert different text encodings. However, you can do other things than text encoding conversion. This is closest in spirit to the C preprocessor method. You can wade through the source code ahead of processing and make whichever changes you see fit.

Is any of this really useful? Probably not as it is. But you never know when you might need to do something exotic and one of these techniques could save the day. You probably couldn’t get away with some of this on MicroPython, of course. Your mileage may vary depending on where you find your Python running — like the Web.

Sundial Collection Is 2D Printed

February 5, 2023 by Al Williams 3 Comments

We see a lot of clocks, and many of the better ones have some 3D printed elements to them. But [Carl Sabanski] shows us his kits for making sundials for either hemisphere using a conventional printer (you know, one that puts ink on paper), some styrofoam, and possibly some other materials like wire coat hangers, threaded rods, thumbtacks, glue, and different papers like transparencies or card stock.

In all, there are 21 different kinds of sundials. Some are pretty standard-looking fare, but there are others, like the pinwheel equatorial sundial or the cycloid polar sundial, which might be surprising. One even uses a CD as a kind of indicator.

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Scratch Your Itch To Program A Microcontroller

February 3, 2023 by Al Williams 19 Comments

One of the fun things about “old school” computers is that it was fairly easy to get kids into programming them. The old Basic interpreters were pretty forgiving, and you could do some clever things easily with very little theory or setup. These days, you are more likely to sneak kids into programming via Scratch — a system for setting up programs via blocks in a GUI. Again, you can get simple results simply. With Scratch or Basic, complex things have a way of turning out complex, but that’s to be expected. If you want to try a Scratch-inspired take on microcontroller programming, check out MicroBlocks. It will work with several common boards, including the micro:bit and the Raspberry Pi Pico. You can use it in a browser or download versions for Linux, Windows, Mac, or even Chromebooks.

You can see a video below about the micro:bit version from a year ago. The tool is advancing, so you’ll find many new features compared to the video, but it will still give you an idea of what’s happening.

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Electron Microscope Conversion Hack

February 1, 2023 by Al Williams 7 Comments

Some of you probably know this already, but there’s actually more than one kind of electron microscope. In electronics work, the scanning electron microscope (SEM) is the most common. You hit something with electrons and watch for secondary electron emissions. However, biologists more often use a TEM — a transmissive electron microscope — which passes electrons through a sample to image it. [Breaking Taps] built a small device to convert his SEM into a TEM.

One key idea is that in a SEM, the beam’s position on the target is the only thing that matters. Any secondary electron detected is a result of that spot’s composition, no matter where you collect them. Common detectors pick up back-scattered electrons bouncing back toward the electron source. There are also low-energy electrons bouncing off in random directions, depending on the topology of the target.

The slow electrons can be attracted by a single detector that has a strong positive charge. TEM doesn’t detect secondary electron emissions. Instead, it passes electrons through a target and collects the ones that pass through a very thin sample using a screen that glows when electrons hit it.

The idea, then, is to create a STEM-SEM device. There’s a sample holder and an angled reflector that shoots electrons passing toward the SEM’s detector. The back-scatter detector is not used, and a shield prevents the detector from seeing secondary emissions from the target itself.

You can buy these, but they are well over $1,000, so in true hacker fashion, [Breaking Taps] made his own. You could, too, but you’d need a pretty good machine shop and — oh yeah — a scanning electron microscope.

While we have seen some home labs with electron microscopes, you need some high-tech vacuum and high-voltage gear, so it isn’t too common. Armed with a STEM, you can even see the shadows of atoms.

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DIY Adjustable Wrench? Nuts!

February 1, 2023 by Al Williams 12 Comments

What do you do if you want a tiny little adjustable wrench? If you’re [my mechanics] you build your own. Where do you get the stock metal? Well, he started with an M20 nut. A few milling operations, a torch, some pliers, and work with a vice resulted in a nice metal blank just the right size to make each part of the wrench, including a new nut for the adjustment.

Want to do this yourself? If you do, we hope you have a well-equipped machine shop. You should also be comfortable working with red-hot metal. Overall, it is an amazing piece of work, and you can watch the whole process in the video below.

Honestly, precision metalworking is a little out of our comfort zone. Like the recent wood bending we’ve seen, we always think, “Yeah, I could so do that!” Then we realize that we really couldn’t. But still fun to watch and maybe a few ideas we might be able to apply next time we have to bend a little metal.

The wrench is a scale model of a larger one, and it looks great. We would have liked to see it in use with a tiny nut, but we imagine it would work just fine. If you get excited about making things from a single piece of metal, may we suggest a nutcracker?

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