DisplayPort: Taming The Altmode

August 3, 2023 by Arya Voronova 7 Comments

The DisplayPort altmode is semi-proprietary, but it can absolutely be picked apart if we try. Last time, we found a cool appnote describing the DisplayPort altmode in detail, switched the FUSB302 into packet sniffing mode and got packet captures, learned about PD VDMs (vendor-defined messages), and successfully replayed the captured messages to switch a USB-C port into the DisplayPort altmode. Today, we will go through the seven messages that summon the DisplayPort altmode, implement them, and tie them all into a library – then, figure out the hardware we need to have DisplayPort work in the wild.

For a start, as you might have seen from the diagram, a single command can be either a request or a response. For instance, if you get a Discover Identity REQ (request), you reply to it with a Discover Identity ACK (response), adding your identity data to your response along the way. With some commands, the DP source will add some data for you to use; for most commands, your DP sink will have to provide information instead – and we’ll do just that, armed with the PDF provided and the packet captures.

We have seven commands we need to handle in order to get DisplayPort out of a compatible USB-C port – if you need a refresher on these commands, page 13 of the ST’s PDF on the DP altmode will show you the message sequence. These commands are: Discover Identity, Discover SVIDs, Discover Modes, Enter Mode, DP Status Update, DP Configure, and Attention. Out of these, the first four are already partially described in the base USB PD standard, the two DP commands afterwards are DisplayPort-altmode-specific but sufficiently described in the PDF we have, and the Attention command is from the base standard as well, mostly helpful for reporting state of the HPD pin. Let’s start with the first two! Continue reading “DisplayPort: Taming The Altmode” →

Truss-Braced Wings Could Bring New Look To Runways Worldwide

August 2, 2023 by Lewin Day 75 Comments

Airliners have looked largely the same for a long time now. The ongoing hunt for efficiency gains has seen the development of winglets, drag reducing films, and all manner of little aerodynamic tricks to save fuel, and hence money.

Boeing now has its eye on bigger, tastier goals. It believes by switching to a truss-braced wing design, it could net double-digit efficiency gains. It’s working together with NASA to see if this concept could change the face of commercial aviation in decades to come.

Aspect Ratio Matters

The ASH 31 glider features wings with an aspect ratio of 33.5, and a lift-to-drag ratio of 56. *Credit: Manfred Munch, CC-BY-SA 3.0*

The key goal of using a truss-braced wing is to enable an airliner to use a wing much thinner and narrower than usual. These “high aspect ratio” wings are far more efficient than the stubbier, wider wings currently common on modern airliners. But why is aspect ratio so important, and how does it help

If you’ve ever looked at a glider, you will have noticed its incredibly long and narrow wings, which stand it apart from the shorter, wider wings used on airliners and conventional small aircraft. These wings are said to have a high aspect ratio, the ratio between the square of the wingspan and the projected area of the wing itself.

These wings are highly desirable for certain types of aircraft, as lift-to-drag ratio increases with aspect ratio. Any wing that generates lift also generates some drag, but this can be minimized through careful wing design. By making the wings longer and narrower, and thus higher in aspect ratio, the wing tip vortices generated by the wing are weakened. This reduces drag on the plane, and quite significantly so. Continue reading “Truss-Braced Wings Could Bring New Look To Runways Worldwide” →

Clipper Windpower: Solutions In Search Of Problems

August 2, 2023 by Bryan Cockfield 69 Comments

The first modern wind turbines designed for bulk electricity generation came online gradually throughout the 80s and early 90s. By today’s standards these turbines are barely recognizable. They were small, had low power ratings often in the range of tens to hundreds of kilowatts, and had tiny blades that had to rotate extremely quickly.

When comparing one of these tiny machines next to a modern turbine with a power rating of 10 or more megawatts with blades with lengths on the order of a hundred meters, one might wonder if there is anything in common at all. In fact, plenty of turbines across the decades share fundamental similarities including a three-blade design, a fairly simple gearbox, and a single electric generator. While more modern turbines are increasingly using direct-drive systems that eliminate the need for a gearbox and the maintenance associated with them, in the early 2000s an American wind turbine manufacturer named Clipper Windpower went in the opposite direction, manufacturing wind turbines with an elaborate, expensive, and heavy gearbox that supported four generators in each turbine. This ended up sealing the company’s fate only a few years after the turbines were delivered to wind farms.

Some history: the largest terrestrial wind turbines were approaching the neighborhood of 2 megawatts, but some manufacturers were getting to these milestones essentially by slapping on larger blades and generators to existing designs rather than re-designing their turbines from the ground up to host these larger components. This was leading to diminishing returns, as well as an increased amount of mechanical issues in the turbines themselves, and it was only a matter of time before the existing designs wouldn’t support this trend further. Besides increased weight and other mechanical stresses on the structure itself, another major concern was finding (and paying for) cranes with enough capacity to hoist these larger components to ever-increasing heights, especially in the remote locations that wind farms are typically located. And cranes aren’t needed just for construction; they are also used whenever a large component like a generator or blade needs to be repaired or replaced. Continue reading “Clipper Windpower: Solutions In Search Of Problems” →

The Past, Present, And Future Of CircuitPython

August 1, 2023 by Tom Nardi 37 Comments

Modern microcontrollers like the RP2040 and ESP32 are truly a marvels of engineering. For literal pocket change you can get a chip that’s got a multi-core processor running at hundreds of megahertz, plenty of RAM, and more often than not, some form of wireless connectivity. Their capabilities have been nothing short of revolutionary for the DIY crowd — on any given day, you can see projects on these pages which simply wouldn’t have been possible back when the 8-bit Arduino was all most folks had access to.

Limor Fried

Thanks to the increased performance of these MCUs, hackers and makers now even have a choice as to which programming language they want to use. While C is still the language of choice for processor-intensive tasks, for many applications, Python is now a viable option on a wide range of hardware.

This provides a far less intimidating experience for newcomers, not just because the language is more forgiving, but because it does away with the traditional compile-flash-pray workflow. Of course, that doesn’t mean the more experienced MCU wranglers aren’t invited to the party; they might just have to broaden their horizons a bit.

To learn more about this interesting paradigm shift, we invited the fine folks at Adafruit to the Hack Chat so the community could get a chance to ask questions about CircuitPython, their in-house Python variant which today runs on more than 400 devices.

Continue reading “The Past, Present, And Future Of CircuitPython” →

Jenny’s Daily Drivers: FreeBSD 13.2

August 1, 2023 by Jenny List 28 Comments

Last month I started a series in which I try out different operating systems with the aim of using them for my everyday work, and my pick was Slackware 15, the latest version of the first Linux distro I tried back in the mid 1990s. I’ll be back with more Linux-based operating systems in due course, but the whole point of this series is to roam as far and wide as possible and try every reasonable OS I can. Thus today I’m making the obvious first sideways step and trying a BSD-based operating system. These are uncharted waters for me and there was a substantial choice to be made as to which one, so after reading around the subject I settled on FreeBSD as it seemed the most accessible.

First, A Bit Of Context

A PC with the FreeBSD boot screen — Success! My first sight of a working FreeBSD installation.

Most readers will be aware that the BSD operating systems trace their heritage in a direct line back to the original AT&T UNIX, while GNU/Linux is a pretty good UNIX clone originating with Linus Torvalds in the early 1990s and Richard Stallman’s GNU project from the 1980s onwards. This means that for Linux users there’s a difference in language to get used to.

Where Linux is a kernel around which distributions are built with different implementations of the userland components, the various BSD operating systems are different operating systems in their own right. Thus we talk about for example Slackware and Debian as different Linux distributions, but by contrast NetBSD and FreeBSD are different operating systems even if they have a shared history. There are BSD distributions such as GhostBSD which use FreeBSD as its core, but it’s a far less common word in this context. So I snagged the FreeBSD 13.2 USB stick file from the torrent, and wrote it to a USB Flash drive. Out with the Hackaday test PC, and on with the show. Continue reading “Jenny’s Daily Drivers: FreeBSD 13.2” →

Ask Hackaday: What’s The Deal With Humanoid Robots?

July 31, 2023 by Lewin Day 43 Comments

When the term ‘robot’ gets tossed around, our minds usually race to the image of a humanoid machine. These robots are a fixture in pop culture, and often held up as some sort of ideal form.

Yet, one might ask, why the fixation? While we are naturally obsessed with recreating robots in our own image, are these bipedal machines the perfect solution we imagine them to be?

Continue reading “Ask Hackaday: What’s The Deal With Humanoid Robots?” →

Hackaday Links: July 30, 2023

July 30, 2023 by Dan Maloney 14 Comments

A couple of weeks ago, we noted with interest that the space shuttle Endeavour (OV85) would be set up as a full-stack launch configuration display, complete with external fuel tank and solid rocket boosters. We predicted that this would result in some interesting engineering, not least of which will be making the entire 20-story stack safe from seismic activity. Looks like we were right on all counts, with this story about the foundation upon which the display will stand, which has been under construction for quite a while now. The base has six seismic isolators that support the 2.4-m thick slab of reinforced concrete that will serve as a perch for the full stack. The 1,800-ton slab will be able to move a meter or so from its resting position during earthquakes. Or perhaps more accurately, the foundation will allow Los Angeles to move as much as it wants while Endeavour rides it out.

If like us you’re worried that seismic loads are vastly different than the loads the spacecraft was actually designed for, relax — it turns out that the flight loads are far in excess of predicted loads from seismic stress. The plan is to build the booster stacks first — the aft skirts, which will support the entire stack, were just bolted in place — then lift the external tank in place between the boosters, and finally hoist the actual orbiter into place. After the stack is complete, the rest of the building will be built around it. We’re really looking forward to seeing some video on this project.

Continue reading “Hackaday Links: July 30, 2023” →