Printing A Log

February 11, 2024 by 16 Comments

We’ve used wood filament before, and we hazily remember a Cura plugin that changed temperatures to create wood grain. But unlike [Patrick Gibney], we never thought of printing a faux wood log coaster that looks like it has rings. Check out the video below to see how it works.

The filament is not really wood, of course, but a polymer — usually PLA — mixed with wood particles. Changing the temperature does a nice job of darkening the wood. However, it also changes the properties of the carrier polymer, and that’s not always a good thing.

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Benchmarking Latency Across Common Wireless Links For MCUs

February 11, 2024 by 13 Comments

Although factors like bandwidth, power usage, and the number of (kilo)meters reach are important considerations with wireless communication for microcontrollers, latency should be another important factor to pay attention to. This is especially true for projects like controllers where round-trip latency and instant response to an input are essential, but where do you find the latency number in datasheets? This is where [Michael Orenstein] and [Scott] over at Electric UI found a lack of data, especially when taking software stacks into account. In other words, it was time to do some serious benchmarking.

The question to be answered here was specifically how fast a one-way wireless user interaction can be across three levels of payload sizes (12, 128, and 1024 bytes). The effective latency is measured from when the input is provided on the transmitter, and the receiver has processed it and triggered the relevant output pin. The internal latency was also measured by having a range of framework implementations respond to an external interrupt and drive a GPIO pin high. Even this test on an STM32F429 MCU already showed that, for example, the STM32 low-level (LL) framework is much faster than the stm32duino one.

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3D Printed DIN Rail Mount Is Attractive

February 11, 2024 by 8 Comments

DIN rails aren’t very common in hobby projects, although you do see them occasionally. But in some industries, they are everywhere. The rail is just a piece of aluminum or steel with slots to hold it to a wall or bulkhead. There are two small lips that equipment like circuit breakers, power supplies, or controllers can attach easily. A common 3D printing project is a way to mount something like a printer controller to DIN rails. [NotLikeALeafOnThe Wind] shows a different take on it: a magnetic holder that temporarily attaches a rail to a ferrous surface.

Of course, mounting the rail is only half the equation. After that, you still need things to mount on the rail. Luckily, there’s no shortage of designs for DIN mounts for many common boards and modules.

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Running UNIX On A Nintendo Entertainment System

February 11, 2024 by 19 Comments

Who wouldn’t want to run a UNIX-like operating system on their NES or Famicom? Although there’s arguably no practical reason for doing so, [decrazyo] has cobbled together a working port of Little Unix (LUnix), which was originally written for the Commodore 64 and 128 by [Daniel Dallmann]. The impetus for this project was initially curiosity, but when [decrazyo] saw that someone had already written a UNIX-like OS for the 6502 processor, it seemed apparent that the NES was too similar to the C64 to not port it.

Much of this is relatively straightforward, as the 6502 MPU in the C64 is nearly identical to the Ricoh 2A03 in the NES, with the latter missing the binary-coded decimal support, which is not a crucial feature. The only significant roadblock was the lack of RAM in the NES. The console has a mere 2 KB of RAM and 2 KB of VRAM, which made it look anemic even next to the C64. Here, a Japan-only accessory came to the rescue: the Famicom Disk System (FDS), which is a proprietary floppy disk-based system that slots into the bottom of the Famicom and was used for games as well as storing saves back in the day.

By using a Famicom with FDS, it was possible to gain an additional 32 kB provided by the FDS, making the userspace utilities available in the shell. The fruits of this labor work well enough that he could also pop it up on an EverDrive cartridge that supports FDS ROMs and boot it up on an unmodified NES. Whether this is cooler than the NES-OS, which we covered previously, is up for debate.

Incidentally, [Maciej Witkowiak] seems to have resumed development on LUnix, with a new release in 2023, so maybe UNIX-on-6502 may see a revival after a few decades of little happening.

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Analog Engineer’s Pocket Reference Needs A Big Pocket

February 10, 2024 by 22 Comments

We always admire when companies produce useful tools or documentation that aren’t specific to their products. For example, consider LTSpice. Sure, it has the company’s models baked in. But there’s no reason you can’t use it for anything. Thanks! We were interested to see Texas Instrument’s fifth edition of the “Analog Engineer’s Pocket Reference” is still freely available. While we aren’t sure a book with nearly 200 pages in it is a “pocket reference,” we do think you’ll enjoy it, even if you don’t want to use TI’s offerings. This book has been around for 50 years, but it is updated periodically, and this version is the fifth iteration.

The book has several sections ranging from conversion between units and color codes to amplifier noise calculations and understanding ADC settling times. Want to know more about PCB microstrips? Page 85.

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Pimp My Pot Redux, Now Cheaper And Even Better

February 10, 2024 by 10 Comments

If there’s one thing we like around here more than seeing an improved version of a project we’ve already covered, it’s when the improvements make the original project cheaper. In the case of this LED ring light for pots and encoders, not only is it cheaper than its predecessors, it’s better looking and easier to integrate into your projects.

Right from its start, [upir]’s “Pimp My Pot” project has been all about bringing some zazzle to rotary controls. Knobs with a pointer and a scale on the panel are okay — especially when they go to eleven — but more lights mean more fun. The fun comes at a price, though; the previous version of “PMP” used an off-the-shelf LED ring light with a unit cost of about $10. Not the end of the world, perhaps, but prohibitive, and besides, where’s the fun in just buying a component specifically made for rotary control indication?

The new version shown in the video below is pin-compatible with the driver board [upir] used for the previous version, which is based on the MAX7219 display driver. Modifying the previous board to accommodate 32 white 0402 LEDs over a 270° arc was no mean feat. [upir] covers both creating the schematic and the PCB layout in some detail, providing his usual trove of tool-chain tips for minimizing the amount of manual work needed.

Wisely, [upir] chose to get his boards assembled by the vendor; getting all those LEDs to line up perfectly is a job best left to the robots. While the board is designed for use with pots that mount on either side, we much prefer mounting the pot’s shaft through the board, as it keeps the LEDs closer to the knob. The final price per board works out to about $6.30 in quantities of ten and falls to a trivial $1.70 each for lots of 1,000. Pretty sweet savings on a pretty sweet-looking build.

This is a cool use of a ring of LEDs, but if you prefer the finger kind, you can make that, too. You can do it the easy way or the hard way.

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Wooden Desk Lamp Uses Unusual Dimmer

February 10, 2024 by 11 Comments

One of the problems with laser cutting projects is that while they look good, they often look like they were laser cut. [Timber Rough] has a wooden desk lamp that not only looks good but has one of the most unusual dimming features we’ve seen.

One thing that stands out is the lamp is made of different kinds of wood, and that helps. But the dimmer is a magnet and Hall effect sensor that levitates. It is hard to explain, but a quick look at the video below will clarify it.

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