Community Profile: David Pride

via Raspberry Pi

This column is from The MagPi issue 55. You can download a PDF of the full issue for free, or subscribe to receive the print edition in your mailbox or the digital edition on your tablet. All proceeds from the print and digital editions help the Raspberry Pi Foundation achieve its charitable goals.

David Pride’s experiences in computer education came slightly later in life. He admits to not being a grade-A student: he left school with few qualifications, unable to pursue further education at university. There was, however, a teacher who instilled in him a passion for computers and coding which would stick with him indefinitely.

David Pride The MagPi Raspberry Pi Community Profile

David joined us at the St James’s Palace community celebration, mingling with the likes of the Duke of York, plus organisers of Jams and clubs, such as Grace and Femi

Welcome to the Community

Twenty years later, back in 2012, David heard of the Raspberry Pi – a soon-to-be-released “new little marvel” that he instantly fell for, head first. Despite a lack of knowledge in Linux and Python, he experimented and had fun. He found a Raspberry Jam and, with it, Pi enthusiasts like Mike Horne and Peter Onion. The projects on display at the Jam were enough to push David further into the Raspberry Pi rabbit hole and, after working his way through several Python books, he began to take steps into the world of formal higher education.

David Pride The MagPi Raspberry Pi Community Profile

David’s determination to access and complete further education in computing has earned him a three-year PhD studentship. Not bad for a “lousy student”

Back to School

With a Mooc qualification from Rice University under his belt, he continued to improve upon his self-taught knowledge, and was fortunate enough to be accepted to study for a master’s degree in Computer Science at the University of Hertfordshire. With a distinction for his final dissertation, David completed the course with an overall distinction for his MSc, and was recently awarded a fully funded PhD studentship with The Open University’s Knowledge Media Institute.

David Pride The MagPi Raspberry Pi Community Profile

Self-playing xylophones, Wiimote air drums, Lego sorters, Pi Wars robots, and more. David is continually hacking toys, giving them new Pi-powered life

Maker of things

The portfolio of projects that helped him to achieve his many educational successes has provided regular retweet material for the Raspberry Pi Twitter account, and we’ve highlighted his fun, imaginative work on this blog before. His builds have travelled to a range of Jams and made their way to the Raspberry Pi and Code Club stands at the Bett Show, as well as to our birthday celebrations.

David Pride The MagPi Raspberry Pi Community Profile

“Pi & Chips – with a little extra source”

His website, the pun-tastic Pi and Chips, is home to the majority of his work; David also links to YouTube videos and walk-throughs of his projects, and relates his experiences at various events. If you’ve followed any of the action across the Raspberry Pi social media channels – or indeed read any previous issues of The MagPi magazine – you’ll no doubt have seen a couple of David’s projects.

David Pride The MagPi Raspberry Pi Community Profile 4-Bot

Many readers will have come across the wonderful 4-Bot before, and it has even made an appearance alongside David in a recent Bloomberg interview. Considering the trillions of possible game positions, David made a compromise and, if you’re lucky, you may just be able to beat it

The 4-Bot, a robotic second player for the family game Connect Four, allows people to go head to head with a Pi-powered robotic arm. Using a Python imaging library, the 4-Bot splits the game grid into 42 squares, and recognises them as being red, yellow, or empty by reading the RGB value of the space. Using the minimax algorithm, 4-Bot is able to play each move within 25 seconds. Believe us when we say that it’s not as easy to beat as you’d hope. Then there’s his more recent air drum kit, which uses an old toy found at a car boot sale together with a Wiimote to make a functional air drum that showcases David’s toy-hacking abilities… and his complete lack of rhythm. He does fare much better on his homemade laser harp, though!

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Use a Drill to Power Your Flipbooks

via hardware – Hackaday

[WolfCat] of Wolfcatworkshop is creating a hand-animated split-flap animation. But what do you use to test your animation once it’s on the split-flaps? Well, to test it out, [WolfCat] used a drill to give it motion. DoodlersAnonymous has some pics and an interview with [WolfCat] about his animation and there are some pictures on his Instagram page.

Technically, what [WolfCat] wanted to make is a “mutoscope,” a hand-cranked precursor to the movie projector that had its heyday in the late 19th and early 20th century. Originally installed in penny arcades and the like, mutoscopes were single-viewer apparatus. The viewer cranks the handle and the animated cards inside rotate around, stopped briefly by a bit of metal at the top in order to show a frame. The basic idea is similar to the way split-flap clocks or signs work.

[WolfCat] hand drew the animation for his movie and then scanned and printed out each frame. The frames were then transferred to a pair of flaps. [WolfCat] wanted to see how it would look when animated, but didn’t have any plans at the time for a case or a hand crank, so he found the closest tool that would do the job – a cordless drill. Attaching the drill and using a bit of card or wood as a stopper, [WolfCat] could see how the end result would look and could then start work on the case and crank.

The drill is a quick and easy way to see what the finished product would look like. Once he’s got it working, [WolfCat] could check out this 3D printed mutoscope case, or this flip dot animated display.


Filed under: hardware

#FreePCB via Twitter to 2 random RTs

via Dangerous Prototypes

BP

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Maker creates his own coilgun using an Arduino Nano

via Arduino Blog

If you suppose that electromagnetically-propelled projectiles are strictly the purview of well-funded government research labs, think again! Using two sets of coils wrapped around custom 3D-printed base structures and an Arduino Nano for control, YouTuber “Gyro” created his own coilgun capable of propelling steel fast enough to dent a piece of wood.

When fired, a photodiode at the end of each electromagnet coil sends a signal to the Arduino. This, in turn, shuts off the coil, allowing it freely escape the barrel.

As noted in his Instructables write-up, the gun is constructed without large capacitors, which can be expensive and dangerous. Instead, two LiPo battery packs are combined to produce around 22 volts, though this and the number of coils used, could be increased to produce a more powerful device!

Product Development and Avoiding Stock Problems

via hardware – Hackaday

You’ve spent months developing your product, your Kickstarter just finished successfully, and now you’re ready to order all the parts. Unfortunately, your main component, an ATmega328P, is out of stock everywhere with a manufacturer lead time of 16 weeks. Now what?

When manufacturing things in large volumes, acquiring enough stock at the right time can be tricky. There can be seasonal shortages with companies trying to get products manufactured and available for Christmas. There can be natural disasters like floods of hard drive factories, or politically-related availability problems like tantalum for capacitors, or maybe new markets open up that increase demand or a new product sucks up all the available supply. The result is all the same; you have a harder time getting what you need. Fortunately, there are some ways to avoid this problem, or at least mitigate it.

Check Lead Times During Development

Don’t design a product with a part that is marked as “Not for new designs” or “Obsolete.” This seems obvious. Look at availability when picking your part. If large distributors like Mouser and Digikey have lots of units in stock, there’s a good chance that it’s a popular part that will continue to be produced, but it’s not in such high demand that they can’t keep it stocked. This is the ideal situation.

Use Common Parts

The more generic the part, the more likely you’ll be able to find suitable alternatives if your primary source fails. 0603 is a super common footprint size, and you can still get 0805 or 0402 parts to work in a pinch. Use common values as well. 1% resistors are just as cheap as 5%, but if you use 10k resistors, you’ll be able to source literally a billion of them with no problems. Try 9.88k, though, and you get only a handful that are 10x the cost.

Lots of conventions have emerged with common parts that make it easy to drop in replacements. The 555 timer is available with different part numbers from TI, Maxim, Microchip, Intersil, the list goes on. They all have essentially the same specs, and definitely the same pinouts and packages. The less specific your design, the easier it is to find lots of suitable components with high availability.

List Critical Features of Each Part

If you want to measure current, you’ll probably use a current sense resistor. You specify a value for the resistor, a package size, and a power rating. Other than that, though, you may not care about any other specs.

Make sure in your schematic that you note the critical specs so that your alternate part search goes easier. If, for example, you need a .01Ohm 2512 resistor rated for at least 1W, then you can get creative in your sourcing, and maybe discover that there is a 3W chip that’s cheaper. When you clearly define which specs matter and which don’t, you can make other parts available for sourcing that may not have been otherwise.

Find Alternate Components

If nobody has the part you specify in stock, you need to be able to list other parts. The previous points touch on this, but it’s worth spelling out in bold. Even during the design phase when you are picking out the parts to use, it’s important to also collect a couple other part numbers that could also work. When I’m searching, I usually filter by the features I need, then sort by price. The first few entries are my primary and alternate components. It’s usually that easy.

Find Alternate Sources

I have a hierarchy of suppliers, and almost always my first choice has the parts I need. It’s a good practice to check your part against multiple sources, though, using tools like Parts.io. If none of your sources can reliably get a particular part you’re interested in, or they all have long lead times, that’s a sign that you should look for a different component.

DON’T buy parts from sketchy sources. In a moment of desperation, you may be tempted to purchase a surprisingly cheap, seemingly identical part from eBay. These parts are fakes or factory rejects or have been damaged or exposed to humidity with rusted connections, or SOMETHING, but they will cause you more problems in the long run. It’s not worth the risk, and you have no idea what may be wrong with the parts that will bite you further down the road.

Design Your Board for Flexibility

A QFN package nested inside a TQFP package for more flexibility in sourcing.

This happened to me, and I have the PCB to prove it. During the product development phase the Atmega328P was in short supply. I wanted to use the TQFP-32 package, but so did the rest of the developed world right then. Fortunately, some suppliers had a QFN package available, so I designed the board with the two packages nested. Since the pinout was identical, and the QFN fit nicely inside, it was easy to do, and it made the board compatible with either package. It may be necessary to design your board so that it can accommodate different components depending on which is available or which production method you use.

Don’t design yourself into a corner with parts that are too niche or not readily available. Paying attention in the early design phases can save a huge hassle later.

Author’s Note: Our parent company Supplyframe has some tools for choosing your parts and managing your supply chain and all that. It wasn’t until I was putting the finishing touches on this article that I remembered this, and realized I might look like a corporate shill if I didn’t at least mention it and disclose that Parts.io linked above is one of those tools.


Filed under: Engineering, Featured, hardware

OK Google, be aesthetically pleasing

via Raspberry Pi

Maker Andrew Jones took a Raspberry Pi and the Google Assistant SDK and created a gorgeous-looking, and highly functional, alternative to store-bought smart speakers.

Raspberry Pi Google AI Assistant

In this video I get an “Ok Google” voice activated AI assistant running on a raspberry pi. I also hand make a nice wooden box for it to live in.

OK Google, what are you?

Google Assistant is software of the same ilk as Amazon’s Alexa, Apple’s Siri and Microsoft’s Cortana. It’s a virtual assistant that allows you to request information, play audio, and control smart home devices via voice commands.

Infinite Looping Siri, Alexa and Google Home

One can barely see the iPhone’s screen. That’s because I have a privacy protection screen. Sorry, did not check the camera angle. Learn how to create your own loop, why we put Cortana out of the loop, and how to train Siri to an artificial voice: https://www.danrl.com/2016/12/01/looping-ais-siri-alexa-google-home.html

You probably have a digital assistant on your mobile phone, and if you go to the home of someone even mildly tech-savvy, you may see a device awaiting commands via a wake word such the device’s name or, for the Google Assistant, the phrase “OK, Google”.

Homebrew versions

Understanding the maker need to ‘put tech into stuff’ and upgrade everyday objects into everyday objects 2.0, the creators of these virtual assistants have allowed access for developers to run their software on devices such as the Raspberry Pi. This means that your common-or-garden homemade robot can now be controlled via voice, and your shed-built home automation system can have easy-to-use internet connectivity via a reliable, multi-device platform.

Andrew’s Google Assistant build

Andrew gives a peerless explanation of how the Google Assistant works:

There’s Google’s Cloud. You log into Google’s Cloud and you do a bunch of cloud configuration cloud stuff. And then on the Raspberry Pi you install some Python software and you do a bunch of configuration. And then the cloud and the Pi talk the clouds kitten rainbow protocol and then you get a Google AI assistant.

It all makes perfect sense. Though for more extra detail, you could always head directly to Google.

Andrew Jones Raspberry Pi OK Google Assistant

I couldn’t have explained it better myself

Andrew decided to take his Google Assistant-enabled Raspberry Pi and create a new body for it. One that was more aesthetically pleasing than the standard Pi-inna-box. After wiring his build and cannibalising some speakers and a microphone, he created a sleek, wooden body that would sit quite comfortably in any Bang & Olufsen shop window.

Find the entire build tutorial on Instructables.

Make your own

It’s more straightforward than Andrew’s explanation suggests, we promise! And with an array of useful resources online, you should be able to incorporate your choice of virtual assistants into your build.

There’s The Raspberry Pi Guy’s tutorial on setting up Amazon Alexa on the Raspberry Pi. If you’re looking to use Siri on your Pi, YouTube has a plethora of tutorials waiting for you. And lastly, check out Microsoft’s site for using Cortana on the Pi!

If you’re looking for more information on Google Assistant, check out issue 57 of The MagPi Magazine, free to download as a PDF. The print edition of this issue came with a free AIY Projects Voice Kit, and you can sign up for The MagPi newsletter to be the first to know about the kit’s availability for purchase.

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