A brand new issue of The MagPi is out in the wild, and one of our favourite projects we read about involved rebuilding an old PDP-9 computer with a Raspberry Pi-based device that tests hundreds of components.

Anders Sandahl loves collecting old computers: “I really like to restore them and get them going again.” For this project, he wanted to build a kind of component tester for old DEC (Digital Equipment Corporation) Flip-Chip boards before he embarked on the lengthy task of restoring his 1966 PDP-9 computer — a two-foot-tall machine with six- to seven-hundred Flip-Chip boards inside — back to working order. 

His Raspberry Pi-controlled DEC Flip-Chip tester checks the power output of these boards using relay modules and signal clips, giving accurate information about each one’s power draw and output. Once he’s confident each component is working properly, Anders can begin to assemble the historic DEC PDP-9 computer, which Wikipedia advises is one of only 445 ever produced.

Logical approach

“Flip-Chip boards from this era implement simple logical functions, comparable to one 7400-series logic circuit,” Anders explains. “The tester uses Raspberry Pi and an ADC (analogue-to-digital converter) to measure and control analogue signals sent to the Flip-Chip, and digital signals used to control the tester’s circuits. PDP-7, PDP-8 (both 8/S and Straight-8), PDP-9, and PDP-10 (with the original KA processor) all use this generation of Flip-Chips. A testing device for one will work for all of them, which is pretty useful if you’re in the business of restoring old computers. 

Rhode Island Computer Museum (RICM) is where The MagPi publisher Brian Jepson and friend Mike Thompson both volunteer. Mike is part of a twelve-year-project to rebuild RICM’s own DEC PDP-9 and, after working on a different Flip-Chip tester there, he got in touch with Anders about his Raspberry Pi-based version. He’s now busily helping write the user manual for the tester unit. 

Warning!
Frazzled Flip-Chips

Very old computers that use Flip-Chips have components operating at differing voltages, so there’s a high chance of shorting them. You need a level shifter to convert and step down voltages for safe operation. 

Mike explains: “Testing early transistor-only Flip-Chips is incredibly complicated because the voltages are all negative, and the Flip-Chips must be tested with varying input voltages and different loads on the outputs.” There are no integrated circuits, just discrete transistors. Getting such an old computer running again is “quite a task” because of the sheer number of broken components on each PCB, and Flip-Chip boards hold lots of transistors and diodes, “all of which are subject to failure after 55+ years”.

Obstacles, of course

The Flip-Chip tester features 15 level-shifter boards. These step down the voltage so components with different power outputs and draws can operate alongside each other safely and without anything getting frazzled. Anders points out the disparity between the Flip-Chips’ 0 and -3V logic voltage levels and the +10 and -15V used as supply voltages. Huge efforts went into this level conversion to make it reliable and failsafe. Anders wrote the testing software himself, and built the hardware “from scratch” using parts from Mouser and custom-designed circuit boards. The project took around two years and cost around $500, of which the relays were a major part. 

Anders favours Raspberry Pi because “it offers a complete OS, file system, and networking in a neat and well-packaged way”, and says it is “a very good software platform that you really just have to do minor tweaks on to get right”. He’s run the tester on Raspberry Pi 3B, 4, and 5. He says it should also run on Raspberry Pi Zero as well, “but having Ethernet and the extra CPU power makes life easier”.

Although this is a fairly niche project for committed computer restorers, Anders believes his Flip-Chip tester can be built by anyone who can solder fairly small SMD components. Documenting the project so others can build it was quite a task, so it was quite helpful when Mike got in touch and was able to assist with the write-up. As a fellow computer restorer, Mike says the tester means getting RICM’s PDP-9 working again “won’t be such an overwhelming task. With the tester we can test and repair each of the boards instead of trying to diagnose a very broken computer as a whole.” 

The MagPi #147 out NOW!

You can grab the new issue right now from Tesco, Sainsbury’s, Asda, WHSmith, and other newsagents, including the Raspberry Pi Store in Cambridge. It’s also available at our online store, which ships around the world. You can also get it via our app on Android or iOS.

You can also subscribe to the print version of The MagPi. Not only do we deliver it globally, but people who sign up to the six- or twelve-month print subscription get a FREE Raspberry Pi Pico W!

The post DEC Flip-Chip tester | The MagPi #147 appeared first on Raspberry Pi.

AI models are adept at distinguishing one winged creature from another. This #MagPiMonday, Rosie Hattersley goes beyond the buzz.

Fun fact that might get you a point in the local pub quiz: Vespa, Piaggio’s iconic scooter, is Italian for wasp, which its buzzing engine sounds a bit like. Less fun fact: nature’s counterpart to the speedy two-wheeler has an aggressive variant that has been seen in increasing numbers across western Europe and which is a direct threat to bees, which are one of their key food sources. Bees are great for biodiversity; Asian hornets (the largest type of eusocial wasp) are not. But it’s only particular hornet species that pose such a threat. Most citizen reports of Asian hornets are native species, and a key issue is ensuring that existing hornet species are not being destroyed on this mistaken assumption. To combat misinformation and alarm at the so-called ‘killer’ hornet (itself a subset of wasp), academics at the University of Exeter have developed a VespAI detector that presents a positive identification system showing where new colonies of the invasive hornet Vespa velutina nigrithorax have begun to spread. The system works by drawing the insects to a pad that is impregnated with tasty (to wasps) smelling foodstuffs.

Considerate response

VespAI provides a nonharmful alternative to traditional trapping surveys and can also be used for monitoring hornet behaviour and mapping distributions of both the Asian hornet (Vespa velutina) and European hornet (Vespa crabro), which is protected in some countries. “Live hornets can be caught and tracked back to the nest, which is the only effective way to destroy them,” explains the team’s research paper.

Creepy feeling

VespAI features a camera positioned above a bait station that detects insects as they land to feed and gets to work establishing whether the curious mite is, in fact, an Asian hornet. The Exeter team developed the AI algorithm in Python, using YOLO image detection models. These identify whether Asian hornets are present and, if so, send an alert to users. Raspberry Pi proved a great choice because of its compact size, ability to run the hornet recognition algorithm, real-time clock, and support for peripherals such as an external battery. The prototype bait station design was made with items that the team had at hand in their lab, including a squirrel baffle for the weather shield, Petri dishes and sponges to hold hornet attractant, and a beehive stand for the monitor to rest on.

Design challenges included optimising the hornet detection algorithm for use on Raspberry Pi. “An AI algorithm may work well during training or when validated in the lab. However, field deployment is essential to expose it to potentially unforeseen scenarios that may return errors”, they note. The project also involved developing a monitor with an integrated camera, processor, and peripherals while minimising power consumption. To this end, the VespAI team is currently optimising their software to run on Raspberry Pi Zero, having watched footage of the AntVideoRecord device monitoring leafcutter ant (Acromyrmex lundi) foraging trails and been impressed by its ability to run for extended periods remotely due to its low power consumption.

As this interactive map shows, Asian hornets have quickly made inroads across Western Europe.

The Raspberry Pi-enabled setup is “intended to support national surveillance efforts, thus limiting hornet incursions into new regions,” explains Dr Thomas O’Shea-Wheller, a research fellow in the university’s Environment and Sustainability Institute. He and his colleagues have been working on the AI project since 2022, conducting additional fieldwork this summer with the National Bee Unit and the Government of Jersey (Channel Islands) mapping new locations and fine-tuning its accessibility to potential users ahead of a planned commercial version. 

Given Raspberry Pi’s extensive and enthusiastic users, they hope sharing their code on GitHub will help expand the number of VespAI detection stations and improve surveillance and reporting of hornet species.

This article originally featured in issue 146 of The MagPi magazine.

The MagPi #146 out NOW!

You can grab the new issue right now from Tesco, Sainsbury’s, Asda, WHSmith, and other newsagents, including the Raspberry Pi Store in Cambridge. It’s also available at our online store, which ships around the world. You can also get it via our app on Android or iOS.

You can also subscribe to the print version of The MagPi. Not only do we deliver it globally, but people who sign up to the six- or twelve-month print subscription get a FREE Raspberry Pi Pico W!

The post Track Asian hornets with VespAI | #MagPiMonday appeared first on Raspberry Pi.

The new and improved MagPi magazine now houses one of my favourite sections of the late great HackSpace magazine: Top Projects. The feature showcases five or six spectacular builds using Raspberry Pi, and this was our favourite from the latest issue.

Do you want a portable mini modular computer based on Raspberry Pi 5? If so, you’re in luck. A small outfit (boasting one-and-a-half people) called Soulcircuit is working on one right now, called the Pilet (it was called Consolo, but is now called Pilet, which according to the maker “reflects the project’s aim to appeal to a wider global audience”). 

Two 8000mAh batteries give the device a claimed seven-hour lifespan, which if true will put a lot of computing power in your pocket for a productive day’s work. The basic unit houses a Raspberry Pi 5 and a touchscreen, running a full-fat version of the Linux operating system (it looks like Debian with a KDE desktop, which wouldn’t really have been practical with any model of Raspberry Pi until now). 

Soulcircuit claims that the Pilet is “built by open-source software for the open-source community,” and credits KiCad, FreeCAD, Blender, Linux, Raspberry Pi, and KDE. As we’ve seen so many times though, it’s not enough just to have the right software; a device this good takes expertise and imagination, and if it can come in at the expected price of under $200, we’re sure it’ll be popular with open-source geeks who want to get work done but also quite like leaving the house every now and then.

The MagPi #146 out NOW!

You can grab the new issue right now from Tesco, Sainsbury’s, Asda, WHSmith, and other newsagents, including the Raspberry Pi Store in Cambridge. It’s also available at our online store, which ships around the world. You can also get it via our app on Android or iOS.

You can also subscribe to the print version of The MagPi. Not only do we deliver it globally, but people who sign up to the six- or twelve-month print subscription get a FREE Raspberry Pi Pico W!

The post Pilet: Mini Pi 5 modular computer appeared first on Raspberry Pi.

This canny way to transfer analogue film to digital was greatly improved by using Raspberry Pi, as Rosie Hattersley discovered in issue 145 of The MagPi.

Gugusse is a French term meaning something ‘quite flimsy’, explains software engineer and photography fan Denis-Carl Robidoux. The word seemed apt to describe the 3D-printed project: a “flimsy and purely mechanical machine to transfer film.” 

Denis-Carl created Gugusse as a volunteer at the Montreal museum where his girlfriend works. He was “their usual pro bono volunteer guy for anything special with media, [and] they asked me if I could transfer some rolls of 16mm film to digital.” Dissatisfied with the resulting Gugusse Roller mechanism, he eventually decided to set about improving upon it with a little help from Raspberry Pi. Results from the Gugusse Roller’s digitisation process can be admired on YouTube.

New and improved

Denis-Carl brought decades of Linux coding (“since the era when you had to write your own device drivers to make your accessories to work with it”), and a career making drivers for jukeboxes and high-level automation scripts, to the digitisation conundrum. Raspberry Pi clearly offered potential: “Actually, there was no other way to get a picture of this quality at this price level for this DIY project.” However, the Raspberry Pi Camera Module v2 Denis-Carl originally used wasn’t ideal for the macro photography approach and alternative lenses involved in transferring film. The module design was geared up for a lens in close proximity to the camera sensor, and Bayer mosaics aligned for extremities of incoming light were at odds with his needs. “But then came Raspberry Pi HQ camera, which didn’t have the Bayer mosaic alignment issue and was a good 12Mp, enough to perform 4K scans.” 

Scene stealer

Denis-Carl always intended the newer Gugusse Roller design to be sprocketless, since this would allow it to scan any film format. This approach meant the device needed to be able to detect the film holes optically: “I managed this with an incoming light at 45 degrees and a light sensitive resistor placed at 45 degrees but in the opposite direction.” It was “a Eureka moment” when he finally made it work. Once the tension is set, the film scrolls smoothly past the HQ camera, which captures each frame as a DNG file once the system detects the controlling arms are correctly aligned and after an interval for any vibration to dissipate. 

The Gugusse Roller uses Raspberry Pi 4 to control the HQ Camera, three stepper motors, and three GPIO inputs. So far it has scanned thousands of rolls of film, including trailers of classics such as Jaws, and other, lesser-known treasures. The idea has also caught the imagination of more than a dozen followers who have gone on to build their own Gugusse Roller using Denis-Carl’s instructions — check out other makers’ builds on Facebook.

The post Gugusse Roller transfers analogue film to digital with Raspberry Pi appeared first on Raspberry Pi.

Who needs to laboriously shuffle their own deck when Raspberry Pi can do it for you? In the latest issue of The MagPi, our recent intern, Louis Wood, tells us all about the nifty LEGO card shuffler he designed during his summer spent in the Maker Lab.

Maker and Cambridge engineering undergraduate Louis Wood first encountered Raspberry Pi while looking for a low-cost microcontroller that could be programmed with Python for an A-level project. Inspiring plenty of envy, he’s just spent six whole weeks ensconced in Raspberry Pi HQ’s very own maker space building a range of Raspberry Pi projects, including a LEGO card shuffler. Basing it around the LEGO Build HAT helped him evolve and improve upon a design that he and his Queens’ College Cambridge friends, Lucas Hoffman and Emily Wang, devised. The card shuffler idea was their response to a design and build challenge, based around a LEGO NXT system, to demonstrate an aspect of engineering science. The dual-motor design was in need of some reworking, which Louis undertook while working as an intern at Raspberry Pi Towers alongside Maker in Residence Toby Roberts.

Quirky and cool

Louis used a LEGO Spike education kit with Raspberry Pi’s LEGO Build HAT to create a simpler but more robust design. The kit includes cycle motors, which he attached directly to the Build HAT’s four connectors. “The Build HAT made it pretty easy to pick up all the motors and plug them in.” He then programmed Raspberry Pi 4 over SSH, “which made it easy to tweak code.”

The MicroPython code produces either a one or a zero and spins either the left or right motor accordingly: “When the motor turns on, the wheel spins a few cards into the middle.” The motors run on a loop, each powering on for a second or two, pushing cards from each side and randomly shuffling them into a central pile until the Build HAT colour sensors detect the black base of either card bay. The card shuffler then skips that side and only runs the opposite motor for a while to clear the rest of the cards. Once it notices it’s done shuffling, it stops.

The build took a couple of hours, and Louis spent a similar time coding and tweaking the build. “The hardest thing was making it so that it doesn’t just spit out the whole side [of cards] at once,” he says.

His simple-but-effective barrier is positioned such that only a single card at a time can (usually) be shuffled along by the motor. The setup doesn’t always work flawlessly, occasionally requiring the user to deftly flick a card back into place, but Louis aims to improve the design by moving apart the two card holding sides to prevent blockages.

The Build HAT came into its own thanks to the colour sensor Raspberry Pi 4 used to detect whether there were still cards awaiting shuffling. The white background of the cards contrasted with the black base of the crates he’d created, which was visible only when the stack of cards was depleted. Other card decks — such as Uno ones, which usually have a black background — could be shuffled too, as long as the card holder base colour was changed.

Makers gonna make

Two weeks into his internship, Louis had already created and written about a ‘Pixie’ tube clock and had been building “a Raspberry Pi mount and cooling system for one of the engineers upstairs, so you can sort of be running eight Raspberry Pis at the same time, fans, and an enclosure,” as well as a remote control based on the brand-new Pico 2.

Given this prodigious rate of design, we asked whether an engineering career or one as a maker is in his future. “I’d like to be a maker, but I think it’s quite hard…” Louis said. “To be a maker YouTuber takes a lot of work and time, I think… probably a bit risky.”

Read the full story, including some extra tips and projects from maker Louis Wood, in The MagPi #146.

The MagPi #146 out NOW!

You can grab the new issue right now from Tesco, Sainsbury’s, Asda, WHSmith, and other newsagents, including the Raspberry Pi Store in Cambridge. It’s also available at our online store, which ships around the world. You can also get it via our app on Android or iOS.

You can also subscribe to the print version of The MagPi. Not only do we deliver it globally, but people who sign up to the six- or twelve-month print subscription get a FREE Raspberry Pi Pico W!

The post It’s all hands OFF deck with this Pi-powered LEGO card shuffler appeared first on Raspberry Pi.