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Hackaday Links: October 31, 2021

Global supply chain issues are beginning to hit closer to home for the hacker community, as Raspberry Pi has announced their first-ever price increase on their flagship Pi 4. The move essentially undoes the price drop on the 2GB version of the Pi 4 that was announced in February, and sets the price back up from $35 to $45. Also rolled back is the discontinuation of the 1GB version, which will now be available at the $35 price point. The announcements come from Eben Upton himself, who insists the price increase is only temporary. We applaud his optimism, but take it with a grain of salt since he also said that 2021 production across the board will stay at the seven million-unit level, which is what they produced in 2020. That seems to speak to deeper issues within the supply chain, but more immediately, it’s likely that the supply of Pi products will be pinched enough that you’ll end up paying above sticker price just to get the boards you need. Hope everyone is stocked up.

On the topic of supply chain issues and their threat to Christmas gift-giving, here’s one product we hope is stranded in a container off Long Beach or better still, bobbing along in the Strait of Juan De Fuca: a toddler’s toy telephone that actually makes and receives calls. Anyone born in the last 60 years probably had one of the Fisher-Price Chatter telephone, a toy that in its original form looked like a desk telephone on wheels that was dragged behind the child, popping along and providing endless hours of clicky amusement as kids twisted the dial and lifted the receiver. Come to think of it, the Chatter telephone may be as close to a dial phone as anyone born since 1990 may have come. Anyway, some genius stuck a Bluetooth module into the classic phone to let it hook up to an app on an actual phone, allowing kids (or more likely their nostalgia-soaked parents) to make and receive calls. It’s actually priced at a reasonable $60, so there might be some hacking potential here.

Also tangential to supply chains, we stumbled across a video guide to buying steel that might interest readers. Anyone who has seen the displays of steel and other metals at the usual big-box retailers might wonder what the fuss is, but buying steel that way or ordering online is a great way to bust a project’s budget. Fabricator and artist Doug Boyd insists that finding a local steel supplier is the best bang for your buck, and has a bunch of helpful tips for not sounding like a casual when you’re ordering. It’s all good advice, and would have helped us from looking foolish a time or two at the metal yard; just knowing that pipe is measured by inside diameter while tubing is measured by outside dimensions is worth the price of admission alone.

With all the money you save on steel and by not buying Raspberry Pis, perhaps you’ll have a couple of hundred thousand Euros lying around to bid on this authentic 1957 Sputnik I satellite. The full-scale model of Earth’s first artificial satellite — manhole covers excluded — was a non-flown test article, but externally faithful to the flown hardware that kicked off the first Space Race. The prospectus says that it has a transmitter and a “modern power supply”; it’s not clear if the transmitter was originally part of the test article or added later. The opening bid is €85,000 and is expected to climb considerably.

And finally, there’s something fascinating about “spy radios,” especially those from the Cold War era and before, when being caught with one in your possession was probably going to turn out to be a very bad day. One such radio is the Radio Orange “Acorn” receiver, which is in the collection of the Crypto Museum. The radio was used by the Dutch government to transmit news and information into the occupied Netherlands from their exile in London. Built to pass for a jewelry box, the case for the radio was made from an old cigar box and is a marvel of 1940s miniaturization. The radio used three acorn-style vacuum tubes and was powered by mains current; another version of the Radio Orange receiver was powered by a bike dynamo or even a water-powered turbine, which could be run from a tap or garden hose. The video below shows the water-powered version in action, but the racket it made must have been problematic for its users, especially given the stakes.

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Raspberry Pi Reads What It Sees, Delights Children

[Geyes30]’s Raspberry Pi project does one thing: it finds arbitrary text in the camera’s view and reads it out loud. Does it do so flawlessly? Not really. Was it at least effortless to put together? Also no, but it does wonderfully illustrate the process of gluing together different bits of functionality to make something new. Also, [geyes30]’s kids find it fascinating, and that’s a win all on its own.

The device is made from a Raspberry Pi and camera and works by sending a still image from the camera to an optical character recognition (OCR) program, which converts any visible text in the image to its ASCII representation. The recognized text is then piped to the espeak engine and spoken aloud. Getting all the tools to play nicely took a bit of work, but [geyes30] documented everything so well that even a novice should be able to get the project up and running in an afternoon.

Sometimes a function like text-to-speech is an end result in and of itself. This was also true of another similar project: Magic Mirror, whose purpose was to tirelessly indulge children’s curiosity about language.

Seeing other projects come to life and learning about new tools is a great way to get new ideas, and documenting them helps cross-pollinate among creative types. Did something inspire you recently, or have you documented your own project? We want to hear about it and so do others, so let us know via the tips line!

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Skeleton Watches You Intensely Because It’s Halloween, Okay

If you’ve ever seen a painting in which the eyes follow you around the room, you might have found that a bit uneasy. [CuriousInventor] has taken that concept further with a skeleton that literally holds a gaze on anyone in its field of view. 

The heart of the system is a Raspberry Pi Zero, fitted with a Pi Camera. Running OpenCV, code is set up to track humans and turn the skeleton’s head to face any that are detected. This is achieved via a servo in the skeleton’s neck. A servo bonnet is used to drive the servos without unnecessarily straining the Raspberry Pi.

The skeleton itself doesn’t look modified in any way, though most of the electronics are mounted inside a pretty obvious plastic box. We’d love to see a version 2 with all the hardware housed neatly inside the skull.

It’s a fun hack that makes for an enjoyable Halloween decoration. OpenCV can do other useful things, too, however, like spotting weeds. Video after the break.

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New Part Day: Raspberry Pi LEGO HAT

The Raspberry Pi Foundation have been busy little bees for the last couple of years producing their own silicon, new boards and now in collaboration with the LEGO Education team a new HAT to connect to the LEGO SPIKE education platform. This new HAT board will work with every Raspberry Pi board with a 40-pin GPIO header.

Based on the RPI2040 microcontroller, it makes an interesting detour away from dumb slave boards, although it looks like the firmware is closed (for now) so you’ll have to make do with the pre-baked capabilities and talk to it with the supplied python library.

According to the documentation, the communication between the Pi and the RPI2040 nestled beneath the HAT PCB is plaintext-over-serial, freeing up the majority of the GPIO pins for other uses. The board uses a surface mount pass-through type header which allows pins from the Pi to protrude through the PCB, allowing stacking more HATs on top. Curiously they decided to mount the PCB with active parts facing down, giving a flat rear surface to park things on. We suspect that decision was made to improve access to the LPF2 connectors, especially if they were surface mount parts.

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Raspberry Pi Tablet Gets Radio Surgical Enhancement

We always get excited when we buy a new tablet. But after a few months, it usually winds up at the bottom of a pile of papers on the credenza, a victim of not being as powerful as our desktop computers and not being as convenient as our phones. However, if you don’t mind a thick tablet, you can get the RasPad enclosure to fit around your own Raspberry Pi so it can be used as a tablet. Honestly, we weren’t that impressed until we saw [RTL-SDR] add an SDR dongle inside the case, making it a very portable Raspberry Pi SDR platform.

The box is a little interesting by itself, although be warned it costs over $200. For that price you get an LCD and driver board, a battery system, speakers, and an SD extension slot with some control buttons for volume and brightness. There’s a video of the whole setup (in German) below.

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The Pi 400 As A PC Peripheral

The Raspberry Pi 400 all-in-one computer is a neat little unit that is powerful enough to take on most humdrum computing tasks while doing an excellent job of freeing up valuable desktop space. But what about those moments when both the Pi and a PC are needed on the same desktop? How can the Pi and the bulky PC keyboard share the same space?

[Gadgetoid] may have the answer, with a clever bit of software that presents the Pi’s mouse and keyboard as peripherals on its USB-C power port. If your PC has a high-power USB socket that can run the Pi then it can use the small computer’s input devices just as well as the Pi itself can. It’s fair to say that the Pi 400’s keyboard is not it’s strongest point, but we can see some utility in the idea.

Running it is simply a case of running an executable from the Pi. Control can be wrested back to Raspberry Pi OS with a simple keystroke. Perhaps it’s not the ultimate desktop experience, but if you’re a die-hard Pi-head there’s plenty of appeal.

Within a few weeks, it’s a year since the launch of the Pi 400. We’ve not seen as many of them as the other Pi models, but you might find our original review to be of interest.

Thanks [Itay] for the tip.

OAK-D Depth Sensing AI Camera Gets Smaller And Lighter

The OAK-D is an open-source, full-color depth sensing camera with embedded AI capabilities, and there is now a crowdfunding campaign for a newer, lighter version called the OAK-D Lite. The new model does everything the previous one could do, combining machine vision with stereo depth sensing and an ability to run highly complex image processing tasks all on-board, freeing the host from any of the overhead involved.

Animated face with small blue dots as 3D feature markers.
An example of real-time feature tracking, now in 3D thanks to integrated depth sensing.

The OAK-D Lite camera is actually several elements together in one package: a full-color 4K camera, two greyscale cameras for stereo depth sensing, and onboard AI machine vision processing with Intel’s Movidius Myriad X processor. Tying it all together is an open-source software platform called DepthAI that wraps the camera’s functions and capabilities together into a unified whole.

The goal is to give embedded systems access to human-like visual perception in real-time, which at its core means detecting things, and identifying where they are in physical space. It does this with a combination of traditional machine vision functions (like edge detection and perspective correction), depth sensing, and the ability to plug in pre-trained convolutional neural network (CNN) models for complex tasks like object classification, pose estimation, or hand tracking in real-time.

So how is it used? Practically speaking, the OAK-D Lite is a USB device intended to be plugged into a host (running any OS), and the team has put a lot of work into making it as easy as possible. With the help of a downloadable application, the hardware can be up and running with examples in about half a minute. Integrating the device into other projects or products can be done in Python with the help of the DepthAI SDK, which provides functionality with minimal coding and configuration (and for more advanced users, there is also a full API for low-level access). Since the vision processing is all done on-board, even a Raspberry Pi Zero can be used effectively as a host.

There’s one more thing that improves the ease-of-use situation, and that’s the fact that support for the OAK-D Lite (as well as the previous OAK-D) has been added to a software suite called the Cortic Edge Platform (CEP). CEP is a block-based visual coding system that runs on a Raspberry Pi, and is aimed at anyone who wants to rapidly prototype with AI tools in a primarily visual interface, providing yet another way to glue a project together.

Earlier this year we saw the OAK-D used in a system to visually identify weeds and estimate biomass in agriculture, and it’s exciting to see a new model being released. If you’re interested, the OAK-D Lite is available at a considerable discount during the Kickstarter campaign.