ESP32 Serial Interface Modernizes Old Equipment

January 27, 2020 by Tom Nardi 25 Comments

There’s still plenty of useful hardware out there that uses an RS-232 interface, like the Behringer Ultradrive loudspeaker systems that [Lasse Lukkari] works with from time to time. Rather than ditch perfectly good gear because modern computers (to say nothing of phones or tablets) don’t have physical serial ports, he decided to come up with a WiFi adapter for these old devices that he calls SerialChiller.

Inside the SerialChiller is an ESP32, a MAX3232 line driver, a LM1117 linear regulator, and a few passives. The professionally manufactured PCB is housed inside of an enclosure that [Lasse] has repurposed from a cheap DB15 breakout adapter. The USB cable is used to power the board and for programming, though it can also be used to turn the SerialChiller into a USB-to-serial cable as well.

The hardware for this project is pretty straightforward, but what we really like is the direction he’s taken with the software. Rather than using the SerialChiller as a simple serial to WiFi bridge, [Lasse] is actually implementing a complete web-based interface directly on the microcontroller. In the video after the break he demonstrates his firmware for controlling the aforementioned Behringer Ultradrive, but that’s just one possible application for the project. Firmware could be spun up for all sorts of classic devices, breathing new life into hardware that might otherwise be in danger of heading to the landfill.

Of course, using the ESP family of chips as serial adapters is hardly anything new. In fact, that’s what they were designed for. But developing modern user interfaces for old hardware thanks to the power of the ESP32 has some fascinating potential.

Continue reading “ESP32 Serial Interface Modernizes Old Equipment” →

A Custom Raspberry Pi 4 Arcade Cabinet

January 25, 2020 by Tom Nardi 29 Comments

Over the years we’ve covered quite a few Raspberry Pi based arcade cabinets, and admittedly many of them have been fairly similar. After all, there’s only so much variation you can make before it stops looking like a traditional arcade machine. But even still, we never tire of seeing a well executed build like the one [Dawid Zittrich] recently shared with us.

These days you can order a kit that has pre-cut panels to build your cabinet with, but looking for a completely custom build, [Dawid] decided to first model his design in SketchUp and then cut out the panels himself with a jigsaw. This obviously is quite a bit more work, and assumes you’ve got sufficient woodworking tools, but we think the final result looks great. Not to mention the fact that it’s going to be a lot stronger than something made out of MDF.

He also created the side artwork himself, taking the logos and names from his favorite arcade and Amiga games and putting them on a retro-looking gradient pattern. The marquee on the top has an acrylic front and is illuminated from behind with strips of LEDs. It’s mounted on a hinge so that it can be lifted up and a new piece of art slid in without taking apart the whole cabinet. While it might be a little more labor intensive to switch out than some of the electronic marquees we’ve seen, we do like that you still have the ability to change the artwork on a whim.

With the cabinet itself completed, [Dawid] turned his attention to the electronics. Inside you’ve got the aforementioned Raspberry Pi 4 (with a Noctua fan to keep it cool), an external hard drive, a HDMI to VGA converter with scanline generator to drive the 4:3 ratio Eizo Flex Scan S2100 monitor, and a rather beefy amplifier hanging off the Pi’s 3.5 mm analog audio output. All of which is easily accessible via a maintenance hatch built into the cabinet so [Dawid] doesn’t need to tear everything down when he wants to tweak something.

If you’d like to have that arcade cabinet feel but don’t have the space and equipment to put something like this together, you could always stick a Raspberry Pi into an iCade and call it a day.

A Retro Touch Pad You Can Use On Modern Computers

January 22, 2020 by Tom Nardi 11 Comments

As [Jan Derogee] explains in the faux-retro video after the break, drawing on classic 8-bit computers was something of a pain. The rudimentary light pens and joysticks of the 1980s allowed for free-form input, but were clumsy and awkward to use. Which is why he set out to create an ideal drawing device for the C64 using modern electronics. For the sake of completion, he also gave it a USB HID mode so it would work on somewhat more modern computers.

His device, which he’s calling the Commo Pad, looks like it could have been transported here directly from the 1980s, but it’s built from entirely new hardware. The case is actually made of wood that [Jan] sanded and painted to give it that chunky plastic aesthetic that we all know and love, and the retro artwork on the touch panel really goes a long way to sell the vintage vibe.

Speaking of which, the touch panel is perhaps the most interesting component of the entire build. It’s actually a resistive panel that was meant for mounting to an LCD that [Jan] has connected to an Arduino. All he had to do was provide a stable frame for it and print out some art work to slide in behind it.

The Arduino and associated electronics allow the Commo Pad to be picked up by the C64 as either a joystick or mouse, which means it doesn’t need any custom software on the computer side to function. Similarly, it can also mimic a USB mouse if you want to plug it into something made a bit later than 1982. Should you be so inclined to make it wireless, the addition of a Bluetooth seems like it would be relatively trivial.

If the Commo Pad doesn’t have enough of a retro-futuristic vibe for your tastes, we recently covered a custom optical touch panel that looked like it could double as a prop from Blade Runner which might do the trick.

Continue reading “A Retro Touch Pad You Can Use On Modern Computers” →

Random Numbers From Outer Space

January 20, 2020 by Kristina Panos 22 Comments

Need a random number? Sure, you could just roll a die, but if you do, you might invite laughter from nearby quantum enthusiasts. If it’s truly, unpredictably random numbers you need, look no farther than the background radiation constantly bombarding us from the safety of its celestial hideout.

In a rare but much appreciated break from the Nixie tube norm of clock making, [Alpha-Phoenix] has designed a muon-powered random number generator around that warm, vintage glow. Muons are subatomic particles that are like electrons, but much heavier, and are created when pions enter the atmosphere and undergo radioactive decay. The Geiger-Müller tube, mainstay of Geiger counters the world over, detects these incoming muons and uses them to generate the number.

Inside the box, a 555 in astable mode drives a decade counter, which outputs the numbers 0-9 sequentially on the Nixie via beefy transistors. While the G-M tube waits for muons, the numbers just cycle through repeatedly, looking pretty. When a muon hits the tube, a second 555 tells the decade counter to stop immediately. Bingo, you have your random number! The only trouble we can see with this method is that if you need a number right away, you might have to go get a banana and wave it near the G-M tube.

Whether this all makes sense or not, you should check out [Alpha-Phoenix]’s project video, which is as entertaining as it is informative. He’s planning a follow-up video focused on the randomness of the G-M tube, so look out for that.

Looking for a cheaper way to catch your random numbers? You can do it with a fish tank, some air pumps, and a sprinkle of OpenCV.

Continue reading “Random Numbers From Outer Space” →

Get Compressed Air From Falling Water With The Trompe

January 17, 2020 by Dan Maloney 24 Comments

If you’re like us, understanding the processes and methods of the early Industrial Revolution involved some hand waving. Take the blast furnace, which relies on a steady supply of compressed air to stoke the fire and supply the oxygen needed to smelt iron from ore. How exactly was air compressed before electricity? We assumed it would have been from a set of bellows powered by a water wheel, and of course that method was used, but it turns out there’s another way to get compressed air from water: the trompe.

As [Grady] from Practical Engineering explains in the short video below, the trompe was a clever device used to create a steady supply of high-pressure compressed air. To demonstrate the process, he breaks out his seemingly inexhaustible supply of clear acrylic piping to build a small trompe. The idea is to use water falling around a series of tubes to create a partial vacuum and entrain air bubbles. The bubbles are pulled down a vertical tube by the turbulence of the water, and then enter a horizontal section where the flow evens out. The bubbles rise to the top of the horizontal tube where they are tapped off by another vertical tube, as the degassed water continues into a second vertical section, the height of which determines the pressure of the stored air. It’s ingenious, requiring no power and no moving parts, and scales up well – [Grady] relates a story about one trompe that provided compressed air commercially for mines in Canada.

Need an electricity-free way to pump water instead of air? Check out this hydraulic ram pump that takes its power from the water it pumps.

Continue reading “Get Compressed Air From Falling Water With The Trompe” →

These Bit Twiddling Tricks Will Make Your Coworkers Hate You

January 16, 2020 by Kerry Scharfglass 32 Comments

In the embedded world, twiddling a few bits is expected behavior. Firmware is far enough down the stack that the author may care about the number of bits and bytes used, or needs to work with registers directly to make the machine dance. Usually these operations are confined to the typical shifting and masking but sometimes a problem calls for more exotic solutions. If you need to descend down these dark depths you invariably come across the classic Bit Twiddling Hacks collected by [Sean Eron Anderson]. Here be dragons.

Discussions of bit math are great opportunities to revisit Wikipedia’s superb illustrations

Bit Twiddling Hacks is exactly as described; a page full of snippets and suggestions for how to perform all manner of bit math in convenient or efficient ways. To our surprise upon reading the disclaimer at the top of the page, [Sean] observes that so many people have used the contents of the page that it’s effectively all been thoroughly tested. Considering how esoteric some of the snippets are we’d love to know how the darkest corners found use.

The page contains a variety of nifty tricks. Interview content like counting set bits makes an early appearance. There’s more esoteric content like this trick for interleaving the bits in two u16’s into a single u32, or rounding up to the next power of two by casting floats. This author has only been forced to turn to Bit Twiddling Hacks on one occasion: to sign extend the output from an unfortunately designed sensor with unusual length registers.

Next time you need to perform an operation with bitmatch, check out Bit Twiddling Hacks. Have you ever needed it in production? How did you use it? We’d love to hear about it in the comments.

The Flexible Permanence Of Copper Tape Circuits

January 15, 2020 by Kristina Panos 23 Comments

Somewhere between shoving components into a breadboard temporarily and committing them to a piece of protoboard or a PCB lies the copper tape method. This flexible Manhattan-style method of circuitry formed the basis for [Bunnie Huang]’s Chibitronics startup, and has since inspired many to stop etching boards and start fetching hoards of copper tape.

[Hales] hit the ground running when he learned about this method, and has made many a copper tape circuit in the last year or so. He offers several nice tips on his site that speak from experience with this method, and he’ll even show you how to easily work an SMD breakout board into the mix.

Generally speaking, [Hales] prefers plywood as the substrate to paper or cardboard for durability. He starts by drawing out the circuit and planning where all the tape traces will go and how wide they need to be. Then he lays out copper traces and pads, rubs the tape against the substrate to make it adhere strongly, and reinforces joints and laps with solder before adding the components. As you can see, copper tape circuits can get pretty complicated if you use Kapton tape as insulation between stacked layers of traces.

Copper and Kapton (polyimide) tape are just two of the many useful tapes you may not be aware of. Stick with us a moment and check out [Nava Whiteford]’s exploration of various adhesive marvels.