PiSquare Lets You Run Multiple HATs On A Raspberry Pi

The Raspberry Pi’s venerable 40-pin header and associated HAT ecosystem for upgrades has been a boon for the platform. It’s easy to stack extra hardware on to a Pi, even multiple times in some cases. However, if you want to run multiple HATs, and wirelessly at that, the PiSquare might just be the thing for you.

The PiSquare consists of a board featuring both RP2040 and ESP-12E microcontrollers. It interfaces with Raspberry Pi HATs and even lets you run multiple of the same HAT on a single Raspberry Pi, as it’s not actually directly using the UART, SPI, or I2C interfaces on the host Pi itself. Instead, the PiSquare communicates wirelessly with the Pi, handling the IO with the HAT itself.

It’s unclear how this works on a software level. Simply using existing software tools and libraries for a given Raspberry Pi HAT probably won’t work with the wireless PiSquare setup. However, for advanced users, it could serve a useful purpose, allowing one Raspberry Pi to command multiple HATs without the fuss of having to run more single-board computers where just one will do. Boards will be available on Kickstarter for those interested in the device.

We’ve seen other creative things done with the Raspberry Pi and the HAT system, too. If you’ve been cooking up your own neat hacks for the platform, drop us a line!

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Hackaday Links: January 23, 2022

When Tonga’s Hunga-Tonga Hunga-Ha’apai volcano erupted on January 15, one hacker in the UK knew just what to do. Sandy Macdonald from York quickly cobbled together a Raspberry Pi and a pressure/humidity sensor board and added a little code to create a recording barometer. The idea was to see if the shock wave from the eruption would be detectable over 16,000 km away — and surprise, surprise, it was! It took more than 14 hours to reach Sandy’s impromptu recording station, but the data clearly show a rapid pulse of increasing pressure as the shockwave approached, and a decreased pressure as it passed. What’s more, the shock wave that traveled the “other way” around the planet was detectable too, about seven hours after the first event. In fact, data gathered through the 19th clearly show three full passes of the shockwaves. We just find this fascinating, and applaud Sandy for the presence of mind to throw this together when news of the eruption came out.

Good news for professional astronomers and others with eyes turned skyward — it seems like the ever-expanding Starlink satellite constellation isn’t going to kill ground-based observation. At least that’s the conclusion of a team using the Zwicky Transient Facility (ZTF) at the Palomar Observatory outside San Diego. ZTF is designed to catalog anything that blinks, flashes, or explodes in the night sky, making it perfect to detect the streaks from the 1,800-odd Starlink satellites currently in orbit. They analyzed the number of satellite transients captured in ZTF images, and found that fully 20 percent of images show streaks now, as opposed to 0.5 percent back in 2019 when the constellation was much smaller. They conclude that at the 10,000 satellite full build-out, essentially every ZTF image will have a streak in it, but since the artifacts are tiny and well-characterized, they really won’t hinder the science to any appreciable degree.

Speaking of space, we finally have a bit of insight into the causes of space anemia. The 10% to 12% decrease in red blood cells in astronauts during their first ten days in space has been well known since the dawn of the Space Age, but the causes had never really been clear. It was assumed that the anemia was a result of the shifting of fluids in microgravity, but nobody really knew for sure until doing a six-month study on fourteen ISS astronauts. They used exhaled carbon monoxide as a proxy for the destruction of red blood cells (RBCs) — one molecule of CO is liberated for each hemoglobin molecule that’s destroyed — and found that the destruction of RBCs is a primary effect of being in space. Luckily, there appears to be a limit to how many RBCs are lost in space, so the astronauts didn’t suffer from complications of severe anemia while in space. Once they came back to gravity, the anemia reversed, albeit slowly and with up to a year of measurable changes to their blood.

From the “Better Late Than Never” department, we see that this week that Wired finally featured Hackaday Superfriend Sam Zeloof and his homemade integrated circuits. We’re glad to see Sam get coverage — the story was also picked up by Ars Technica — but it’s clear that nobody at either outfit reads Hackaday, since we’ve been featuring Sam since we first heard about his garage fab in 2017. That was back when Sam was still “just” making transistors; since then, we’ve featured some of his lab upgrades, watched him delve into electron beam lithography, and broke the story on his first legit integrated circuit. Along the way, we managed to coax him out to Supercon in 2019 where he gave both a talk and an interview.

And finally, if you’re in the mood for a contest, why not check out WIZNet’s Ethernet HAT contest? The idea is to explore what a Raspberry Pi Pico with Ethernet attached is good for. WIZNet has two flavors of board: one is an Ethernet HAT for the Pico, while the other is as RP2040 with built-in Ethernet. The good news is, if you submit an idea, they’ll send you a board for free. We love it when someone from the Hackaday community wins a contest, so if you enter, be sure to let us know. And hurry — submissions close January 31.

Forget Smart Watch; Build A Smart Hat

Smart watches are pretty common today, but how many people do you know with a smart hat? [Oliver] built Wilson which he bills as “the IoT hat.” We wonder if the name was inspired by the Home Improvement character of the same name who only appeared as a hat above the fence line. You can see a video of the project, below.

The project is pretty straightforward for hardware. An LED strip, an Arduino, and a Bluetooth module. Oh. And a hat. The software, as you might expect, is a bit more complex. It allows you to display SMS messages to your hat.

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How To Keep Your Head Warm With A Skirt

We’re not sure what we like better about this upcycled trapper hat — that [ellygibson] made it as a tribute to Holden Caulfield, the anti-hero of the classic teen angst novel The Catcher in the Rye, or the fact that she made it out of a skirt that cost a dollar from the thrift store. Oddly enough, one dollar is exactly what Holden paid for his hat in the book.

To make this hat, [elly] started by measuring the circumference of her head, then used math to figure out the radius of the circle for the top part. She made a prototype first to get the fit right, then cut the pieces from the skirt and the lining pieces from black flannel. We love that [elly] used the tiny pocket from the skirt in one of the ear flaps, because it will surely come in handy one day.

[elly] doesn’t provide pattern pieces, but that’s okay — between the explanation of how she arrived at the hat band circumference and the step-by-step instructions, it should be easy to make one of these for yourself from whatever fabric you’ve got.

Before you go cutting up an old coat, consider whether it could be fixed. Remember when [Ted Yapo] fixed the zipper box on his son’s winter coat by printing a replacement? Or how about the time [Gerrit Coetzee] cast his own pea coat buttons?

A Raspberry Pi 400 UPS Add-On, It’s Not All Plain Sailing

Since the recent launch of the all-in-one Raspberry Pi 400, the global hardware community have taken to the new platform and are investigating its potential for hardware enhancements. On the back it has the same 40-pin expansion connector as its single-board siblings, but it’s horizontal rather than vertical, which means that all of the conventional HATs sit in a rather ungainly upright position.

One of the first Pi 400 HATs we’ve seen comes from [Patrick Van Oosterwijck], who has made a very neat 18650-based UPS add-on that is intended to eventually fit in the back of the machine in a similar way to the home computer cartridge peripherals of old. Unfortunately not all has gone according to plan, and in finding out why that is the case we learn something about the design of the 400, and maybe even take a chance to reflect on the Pi Foundation itself.

On the face of it the 400’s interface is the same as that of its single board computer stablemates, but something this project reveals is that its 5 V pins have a current limit of 1 A. This turns out to preclude the type of plug-in Pi UPS that sits on a HAT that we’re used to, in that 1 A through the 5 V pin is no longer enough to run the computer.

This effectively puts a stop to [Patrick]’s project, though he can repurpose it for a Pi 4 and its siblings once he’s dealt with a converter chip overheating problem. He does however make a complaint about the Pi Foundation’s slowness in releasing such data about their products, and given that long-time Pi-watchers will remember a few other blips in the supply of Pi hardware data he has a point. A quick check of the Raspberry Pi GitHub repository reveals nothing related to the Pi 400 at the time of writing, and though it shares much with its Pi 4 sibling it’s obvious that there are enough differences to warrant some extra information.

Hardware hackers may not be part of the core education focus of the Pi range, but a healthy, interested, and active hardware community that feels nurtured by its manufacturer remains key to the supply of interesting Pi-related products feeding into that market. We’d like to urge the Pi Foundation to never forget the hardware side of their ecosystem, and make hardware specification an integral part of every product launch on day one.

If the Pi 400 catches your interest, you can read our review here.

True Networked KVM Without Breaking The Bank

For administering many computers at once, an IP KVM is an invaluable piece of equipment that makes it possible to get the job done over the network without having to haul a keyboard, monitor, and mouse around to each computer. The only downside is that they can get pricey, unless of course you can roll one out based on the Raspberry Pi and the PiKVM image for little more than the cost of the Pi itself.

The video linked below shows how to set all of this up, which involves flashing the image and then setting up the necessary hardware. The build shows an option for using HDMI over USB, but another option using the CSI bus would allow for control over options like video resolution and color that a USB HDMI dongle doesn’t allow for. It also makes it possible to restart the computer and do things like configure BIOS or boot from removable media, which is something that would be impossible with a remote desktop solution like VNC.

The creator of PiKVM was mentioned in a previous post about the creation of the CSI bus capture card, and a Pi hat based on this build will be available soon which would include options for ATX controls as well. Right now, though, it’s possible to build all of this on your own without the hat, and is part of what makes the Pi-KVM impressive, as well as its very low cost.

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Baseball Cap Mouse Provides A Look-And-Click Interface

Once upon a time, the computer mouse didn’t exist. Early computers used a variety of other input devices, from the typical keyboard to more esoteric options such as joysticks or light pens. While the mouse as we know it dominates all, it doesn’t mean other tools can’t find their place. One such device is this hat mouse, from [Jacek Fedorynski].

The mouse consists of an Adafruit Feather nRF52840 Sense, mounted upon a basic baseball cap. The development board packs in a 9 degree-of-freedom motion sensor package featuring the ST LSM6DS33 acceleromater/gyro and LIS3MDL magnetometer. Through a robust sensor fusion algorithm, this enables the board to measure the orientation and motion of the wearer’s head with a great degree of finesse. This allows the user to look at different parts of the screen to move the mouse cursor, with the system working in an absolute rather than relative fashion. Commands are sent to the attached PC with the Feather’s built-in Bluetooth, avoiding the need for dangly cables running down the user’s neck. Files are available on Github for those eager to spin up their own.

Combined with some built-in accessibility aids in Windows, the setup allows the user to move the mouse well, with foot switches used to activate the left and right mouse buttons. For those who find using a traditional mouse difficult, this could be a great tool for better productivity. Of course, if you wish to learn more, it pays to take a look back at the very earliest days of mouse technology. Video after the break.

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