Illuminated smart curtain in front of a window, beside a Christmas tree

Smart LED Curtain Brings Sprites To Your Windows

January 14, 2023 by 13 Comments
Mobile interface for LED smart curtain display
A mobile interface is a nice touch

Anybody who has ever seen a video wall (and who hasn’t?) will be familiar with the idea of making large-scale illuminated images from individual coloured lights. But how many of us have gone the extra mile and fitted such a display in our own homes? [vcch] has done just that with his Deluxe Smart Curtain that can be controlled with a phone or laptop.

The display itself is made up of a series of Neopixel strips, hung in vertical lines in front of the window.  There is a wide gap between each strip, lending a ghostly translucent look to the images and allowing the primary purpose of the window to remain intact.

The brains of the system are hosted on a low-cost M5stack atom ESP32 device. The data lines for the LEDs are wired in a zig-zag up and down pattern from left to right, which the driver software maps to the rectangular images. However, the 5V power is applied to the strips in parallel to avoid voltage drops along the chain.

If you’d like to build your own smart curtain, Arduino sketch files and PHP for the mobile interface are included on the project page. Be sure to check out the brief video of what the neighbors will enjoy at night after the break.

If video walls are your kind of thing, then how about this one that uses Ping Pong Balls as diffusers? Continue reading “Smart LED Curtain Brings Sprites To Your Windows” →

A Simple Serial Display

January 9, 2023 by 11 Comments

Often with more “modern” complex protocols involving handshaking, token exchanges, and all the other hoops and whistles accompanying them, we forget how useful and powerful serial can be. In what might be a wonderful tribute to that, [Davide Gironi] created a simple AVR-powered 16-digit serial display.

It can display two numbers, and that’s it. A MAX7219 drives the display, and the brains are an ATmega8. It’s straightforward to send new values: a start byte, a CRC, the data to display, and an end byte. A CP2102 provides a UART to USB interface to connect to a host. An EEPROM helps it remember the last numbers shown. It supports positive, negative, and floating-point numbers.

This is a beautiful example of doing one thing and doing it well. The design is simple and allows it to be used for anything. You can show the current stock market price, the time for the next two trains for your commute, or whatever else you can think of. [Davide] included a schematic, code, and a 3d printed enclosure.

Perhaps the idea could be combined with a clever design for a single-motor seven-segment display.

Continue reading “A Simple Serial Display” →

Showing a board with a Pi Pico plugged into it, a USB-A socket marked "USB host", and a character display that says "PASSED" referring to the board being the brains of a testing jig.

USB Host On RP2040 – With PIO

December 28, 2022 by 11 Comments

Folks from [Adafruit] are showing off a neat hack – USB host on RP2040, using the now-famous PIO peripheral. [Adafruit] builds a lot of RP2040 boards, and naturally, you gotta test them before you ship them to customers. They’ve been using very specific Teensies for that, and at some point, those became unobtainium. Based on the work of [sekigon-gonnoc] and with help of [Thach], they’ve made their TinyUSB library support bitbanging of USB over PIO, and successfully ported their test jig firmware to it!

The base Pico-PIO-USB repo by [sekigon-gonnoc] shows a pretty impressive state of affairs – with low-speed and full-speed USB host and full-speed USB device modes supported, and quite a few examples to get you started. [Adafruit]’s work integrates this code into their TinyUSB stack, specifically focusing on MST (mass storage) features – as this is what you need to program a RP2040. Of course, they also provide a mass storage example to boot!

Test jigs are pretty important to have when making multiple pieces of a board, and with RP2040 supporting more and more interfaces thanks to PIO, it sounds like the perfect chip for your next production testing-intended PCB. With the jig brains taken care of, you’ll want to look into building no less important mechanical part, and we’ve covered quite a few ways to sort that out – here’s an OpenSCAD script that generates lasercutting files out of KiCad boards, or a jig built out of scrap copperclad FR4, and a pretty extensive tutorial on making your own lasercuttable jigs, to boot.

Continue reading “USB Host On RP2040 – With PIO” →

VR Sickness: A New, Old Problem

November 29, 2022 by 56 Comments

Have you ever experienced dizziness, vertigo, or nausea while in a virtual reality experience? That’s VR sickness, and it’s a form of motion sickness. It is not a completely solved problem, and it affects people differently, but it all comes from the same root cause, and there are better and worse ways of dealing with it.

If you’ve experienced a sudden onset of VR sickness, it was most likely triggered by flying, sliding, or some other kind of movement in VR that caused a strong and sudden feeling of vertigo or dizziness. Or perhaps it was not sudden, and was more like a vague unease that crept up, leaving you nauseated and unwell.

Just like car sickness or sea sickness, people are differently sensitive. But the reason it happens is not a mystery; it all comes down to how the human body interprets and reacts to a particular kind of sensory mismatch.

Why Does It Happen?

The human body’s vestibular system is responsible for our sense of balance. It is in turn responsible for many boring, but important, tasks such as not falling over. To fulfill this responsibility, the brain interprets a mix of sensory information and uses it to build a sense of the body, its movements, and how it fits in to the world around it.

These sensory inputs come from the inner ear, the body, and the eyes. Usually these inputs are in agreement, or they disagree so politely that the brain can confidently make a ruling and carry on without bothering anyone. But what if there is a nontrivial conflict between those inputs, and the brain cannot make sense of whether it is moving or not? For example, if the eyes say the body is moving, but the joints and muscles and inner ear disagree? The result of that kind of conflict is to feel sick.

Common symptoms are dizziness, nausea, sweating, headache, and vomiting. These messy symptoms are purposeful, for the human body’s response to this particular kind of sensory mismatch is to assume it has ingested something poisonous, and go into a failure mode of “throw up, go lie down”. This is what is happening — to a greater or lesser degree — by those experiencing VR sickness.

Continue reading “VR Sickness: A New, Old Problem” →

A Hacker Walks Into A Trade Show: Electronica 2022

November 22, 2022 by 24 Comments

Last week, the world’s largest electronics trade fair took place in Munich, so I had to attend. Electronica is so big that it happens only once every two years and fills up 14 airplane hangars. As the fairly generic name suggests, it covers anything and everything having to do with electronics. From the producers of your favorite MLCC capacitors to the firms that deliver them to your doorstep, from suppliers of ASIC test equipment to the little shop that’ll custom wind toroids for you, that’s a pretty wide scope. Walking around, I saw tomorrow’s technology today from the big players, but I also picked up some ideas that would be useful for the home gamer.

When I first walked in, for instance, I ran into the Elantas booth. They’re a company that makes flexible insulation and specialty industrial coatings. But what caught my eye was a thermoformed plastic sheet with circuit traces on it. To manufacture them, they cut out copper foil, glue it to a flat plastic sheet with a glue that has a little give, and then put it all together into a vacuum former. The result is a 3D circuit and organically formed substrate in one shot. Very cool, and none of the tech for doing that is outside of the reach of the determined hacker.

The Cool Stuff

All of the stands, big or small, try to lure you in with some gimmick. The big fish, firms with deep pockets, put up huge signs and open bars, and are staffed by no shortage of salespeople in suits. The little fish, on the other hand, have to resort to showing you the cool stuff that they do, and it’s more often the application engineers sitting there, ready to talk tech. You can guess which I found more interesting.

For instance when I walked up to an obviously DIY popcorn popper that was also showing 5000 FPS footage of kernels in mid-pop, I had to ask. The company in question was a small UK outfit that made custom programmable power supplies and digital acquisition gear that interfaced with it. You could plug in their box to some temperature probes, fire off the high-speed video camera, and control the heating and cooling profile without writing any code. Very sweet. Continue reading “A Hacker Walks Into A Trade Show: Electronica 2022” →

Big Brother Or Dumb Brother? Bus Drivers In Beijing Are Forced To Wear “Emotional Monitors”

October 3, 2022 by 64 Comments

Humans aren’t always great at respecting each other’s privacy. However, common sense says there’s a clear boundary when it comes to the thoughts in one’s own head and the feelings in one’s heart.

For bus drivers in Beijing though, it seems that’s no longer the case. These professional drivers are now being asked to wear emotional monitors while on the job, raising concerns from both legal and privacy advocates. But the devices aren’t really anything more than workout monitors, and whether they can actually make good on their Orwellian promise remains to be seen.

In Your Head, In Your Head!

The monitoring wristbands have been rolled out to some of Beijing’s long-distance bus drivers. Credit: Cypp0847, CC-BY-SA-4.0

When George Orwell wrote 1984, it was only 1949. However, he was able to foresee a world in which surveillance was omnipresent and inescapable. He also envsioned the concept of thoughtcrime, where simply contemplating the wrong things could get you in serious trouble with the authorities.

As we all know, Orwell was way off – these predictions didn’t become reality until well into the 2000s. In the latest horrifying development, technologies now exist that claim to be able to monitor one’s emotional state. Now, China’s transportation sector is rushing to push them on their workforces.

Long-distance bus drivers in Beijing are now being told to wear electronic wristbands when on the job. These wristbands claim to be able to capture the wearer’s emotional state, monitoring it on behalf of the employer. The scheme was the idea of the Beijing Public Transport Holding Group. The state-run organization claims the technology is intended for the safety of the public, and a trial of the wristbands began in July this year. Continue reading “Big Brother Or Dumb Brother? Bus Drivers In Beijing Are Forced To Wear “Emotional Monitors”” →

Sketch of a Tandy TRS-80 Model 100 with Arduino Mega 2560

TRS-80 Model 100 Gets Arduino Heart Transplant

September 23, 2022 by 4 Comments

When [Stephen Cass] found himself with a broken Tandy TRS-80 Model 100 portable computer, the simplest solution was to buy another broken one and make one working computer from two non-working computers. However, this left him with a dilemma — what to do with the (now even more) broken one left over?

LCD layout is unusual by modern standard, but optimized for fast updates

Naturally, he did what a lot of us would do and used modern hardware to interface with the original parts that still work. In this case it meant replacing the motherboard with an Arduino Mega 2560.

Luckily, the Model 100 has a substantial fanbase and there’s a lot of helpful information available online, including the detailed service manual, that helped [Stephen] to understand how to drive the unusual display.  The LCD has a resolution of 240×64 pixels, which are broken down into eight zones of 50×32 pixels, and two zones of 40×42 pixels.  Each zone is then further divided into four banks, eight pixels tall, so that each column of eight pixels corresponds to a single byte.

Every one of the ten zones is controlled by an individual HD44102 driver IC, connected to a 30-bit wide bus for selecting the correct chip, bank and column.

With the Arduino handling the data, the old LCD still needed a -5 V supply for contrast and an RC filter to smooth out the PWM signal [Stephen] is using to adjust the viewing angle.

With the new interface, [Stephen] is able to access all of the pixels on the original display, and to use modern graphics libraries such as displayio. With the display issue solved, he intends to use a separate Teensy 4.1 to connect with the keyboard matrix and provide a VT100 terminal interface.

Schematic of the HD44102 driver circuit

Upcycling old, broken hardware can be a lot of fun and is always educational.  Understanding why certain design decisions were made at a time when the engineering trade-offs were different can lead to insights that are directly relevant to modern designs when resources get tight. In this case, the quirky LCD drivers were a response to making the display of text as efficient as possible, so as not to overburden the processor.

The TRS-80 computers are ripe for hacking, with their “built-for-service” designs, and we’ve featured a few in the past.  Some have replaced the motherboard with something newer, like [Stephen], whereas others have also replaced the display, or connected them to the cellphone network.

Have you found new ways to get old hardware working? Tell us in the comments below or send us a message on the Hackaday tips line.

Thanks to [nb0x0308] for the tip!