Surf’s Up, A Styrofoam Ball Rides The Waves To Create A Volumetric Display

March 19, 2021 by Michael Shaub 22 Comments

We are big fans of POV displays, particularly ones that move into 3D. To do so, they need to move even faster than their 2D cousins. [danfoisy] built a volumetric display that doesn’t move LEDs or any other digital display through space, or project light onto a moving surface. All that moves here is a bead of styrofoam and does so at up to 1 meter per second. Having low mass certainly helps when trying to hit the brakes, but we’re getting ahead of ourselves.

[danfoisy] and son built an acoustic levitator kit from [PhysicsGirl] which inspired the youngster’s science fair project on sound. See the video by [PhysicsGirl] for an explanation of levitation in a standing wave. [danfoisy] happened upon a paper in the Journal Nature about a volumetric display that expanded this one-dimensional standing wave into three dimensions. The paper described using a phased array of ultrasonic transducers, each with a 40 kHz waveform.

After reading the paper and determining how to recreate the experiment, [danfoisy] built a 2D simulation and then another in 3D to validate the approach. We are impressed with the level of physics and programming on display, and that the same code carried through to the build.

[danfoisy] didn’t stop with the simulations, designing and building control boards for each ~~100 x 100~~ 10 x 10 grid of transducers. Each grid is driven by 2 Intel Cyclone FPGAs and all are fed 3D shapes by a Raspberry Pi Zero W. The volume of the display is 100 mm x 100 mm x 145mm and the positioning of the foam ball is accurate down to .01 mm though currently there is considerable distortion in the positioning.

Check out the video after the break to see the process of simulating, designing, and testing the display. There are a number of tips along the way, including how to test for the polarity of the transducers and the use of a Python script to place the grids of transducers and drivers in KiCad.

Continue reading “Surf’s Up, A Styrofoam Ball Rides The Waves To Create A Volumetric Display” →

This Week In Security: Spectre In The Browser, Be Careful What You Clone, And Hackintosh

March 19, 2021 by Jonathan Bennett 12 Comments

Google has been working on mitigations for the Spectre attack, and has made available a Proof of Concept that you can run in your browser right now. Spectre is one of the issues that kicked off the entire series of speculative execution vulnerabilities and fixes. What Google has demonstrated is that the Spectre attack can actually be pulled off in Javascript, right in the browser. Spectre is limited to reading memory allocated to the same process, and modern browsers have implemented measures like site isolation, which puts each site in a separate, sandboxed process.

These security features don’t mean that there is no practical dangers from Spectre. There are a handful of ways an attacker can run Javascript on another site, from something as simple as an interactive advertisement, to a cross-site scripting injection. Google has produced features and guidance to mitigate those dangers.

Via Bleeping Computer. Continue reading “This Week In Security: Spectre In The Browser, Be Careful What You Clone, And Hackintosh” →

Interfacing The Dreamcast Controller With Just An Arduino

March 19, 2021 by Lewin Day 5 Comments

The Dreamcast is a somewhat forgotten console today, but for a shining minute in the late 1990s, it was possible to believe Sega were still in the fight. Regardless, their hardware lives on, lovingly preserved by collectors and enthusiasts. [Nicholas FitzRoy-Dale] is one such enthusiast, and set about interfacing the old console’s controllers to an Arduino.

Initial work involved getting the Arduino (presumably a basic 16 Mhz Uno) to read the controller’s buttons, and spitting the data out over serial. The Dreamcast’s Maple bus is fast, which presented some challenges, but it was simple enough. [Nicholas] then moved on to interfacing the VMU, the Dreamcast’s fancy controller-mounted memory card. After initial attempts were shaky and unstable, he redoubled his efforts. Research indicated that the VMU can vary the speed of the bus when it’s in control, so he updated his code to suit. It’s full of great hacks, like connecting the Dreamcast’s two data pins to four input pins on the Arduino, to save a handful of cycles by not having to shift incoming data.

The work is a great read for anyone into assembly-level optimisation of interfaces, as well as proper use of limited resources. Obviously, it’s easy to just throw a faster, more expensive microcontroller at the problem, but then nobody would have learned anything. We’ve featured a great many Dreamcast hacks over the years; [Nicholas]’s work here builds upon [Dmitry]’s work in 2017. We can’t wait to see what comes next out of the underground Sega hacking scene!

High Speed Flight In A Homebrew FPV Cockpit

March 19, 2021 by Lewin Day 13 Comments

First-person view, or FPV, has become hugely popular in RC flying circles. A pair of video goggles lets the pilot fly with vision from the plane itself. To make things even more realistic, the team at [FliteTest] built a replica cockpit with working controls and took it down to the field for testing. (Video, embedded below.)

Since the pilot is wearing video goggles, aesthetics aren’t the key here. A RC transmitter was gutted for its gimbal and potentiometers. The former fitted with a long stick for aileron and elevator control, and the latter hooked up to pedals for the rudder. There’s even a proper throttle handle. It’s a low-budget build, with PVC pipe and bungee straps doing much of the work, but that doesn’t detract from the fun factor one bit. The team later upped the stakes, flying a faster model with the rig at speeds up to 120 mph.

Interesting to note is the somewhat visceral reaction by the pilot when crashing, as the combination of first-person view video and realistic controls gives a powerful sense that one is actually in a real plane. FPV flying actually has a longer history than you might expect, with roots as far back as the 1980s. Continue reading “High Speed Flight In A Homebrew FPV Cockpit” →