App note: How to determine if an eFuse system can be safely hot−plugged

This app note from ON Semiconductors linked here (PDF)

System designers must account for voltage surges that occur when supplies or loads are connected. eFuses are integrated circuits with many features to protect loads from these surges. However, it is important to ensure that the eFuse itself will not receive excessive voltage on its input.
This application note uses mathematical calculations, simulations, and actual lab data to illustrate the voltage surge as an eFuse is suddenly connected on the input side. System designers can use this information to make certain that the eFuse will be within its limits.

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App note: Analysis of power dissipation and thermal considerations for high voltage gate drivers

App note from ON Semiconductors on ways to dissipate thermals or reduce junction temperature of HVIC. Link here (PDF)

Gate drivers used to switch MOSFETs and IGBTs at high frequencies can dissipate significant amount of power depending on the operating conditions. It is important to determine the driver power dissipation and the resulting junction temperature in the application to ensure that the part is operating within acceptable temperature limits.

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Sue Sentance recognised with Suffrage Science award

We’re pleased to share that Dr Sue Sentance, our Chief Learning Officer, is receiving a Suffrage Science award for Mathematics and Computing today.

Sue Sentance

The Suffrage Science award scheme celebrates women in science. Sue is being recognised for her achievements in computer science and computing education research, and for her work promoting computing to the next generation.

Sue is an experienced teacher and teacher educator with an academic background in artificial intelligence, computer science, and education. She has made a substantial contribution to research in computing education in school over the last ten years, publishing widely on the teaching of programming, teacher professional development, physical computing, and curriculum change. In 2017 Sue received the BERA Public Engagement and Impact Award for her services to computing education. Part of Sue’s role at the Raspberry Pi Foundation is leading our Gender Balance in Computing research programme, which investigates ways to increase the number of girls and young women taking up computing at school level.

Suffrage Science Maths and Computing Brooch and Bangle
The awards are jewellery inspired by computing, mathematics, and the Suffragette movement

As Dr Hannah Dee, the previous award recipient who nominated Sue, says: “[…] The work she does is important — researchers need to look at what happens in schools, particularly when we consider gender. Girls are put off computing long before they get to universities, and an understanding of how children learn about computing and the ways in which we can support girls in tech is going to be vital to reverse this trend.”

Sue says, “I’m delighted and honoured that Hannah nominated me for this award, and to share this honour with other women also dedicated to furthering the fields of mathematics, computing, life sciences, and engineering. It’s been great to see research around computing in school start to gather pace (and also rigour) around the world over the last few years, and to play a part in that. There is still so much to do — many countries have now introduced computing or computer science into their school curricula as a mandatory subject, and we need to understand better how to make the subject fully accessible to all, and to inspire and motivate the next generation.”

A girl doing Scratch coding in a Code Club classroom

Aside from her role in the Gender Balance in Computing research programme, Sue has led our work as part of the consortium behind the National Centre for Computing Education and is now our senior adviser on computing subject knowledge, pedagogy, and the Foundation’s computing education research projects. Sue also leads the programme of our ongoing computing education research seminar series, where academics and educators from all over the world come together online to hear about and discuss some of the latest work in the field. 

We are currently inviting primary and secondary schools in England to take part in the Gender Balance in Computing project.

Congratulations from all your colleagues at the Foundation, Sue!

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Code your own Artillery-style tank game | Wireframe #44

Fire artillery shells to blow up the enemy with Mark Vanstone’s take on a classic two-player artillery game

Artillery Duel was an early example of the genre, and appeared on such systems as the Bally Astrocade and Commodore 64 (pictured).

To pick just one artillery game is difficult since it’s a genre in its own right. Artillery simulations and games have been around for almost as long as computers, and most commonly see two players take turns to adjust the trajectory of their tank’s turret and fire a projectile at their opponent. The earliest versions for microcomputers appeared in the mid-seventies, and the genre continued to develop; increasingly complex scenarios appeared involving historical settings or, as we saw from the mid-90s on, even offbeat ideas like battles between factions of worms.

To code the basics of an artillery game, we’ll need two tanks with turrets, a landscape, and some code to work out who shot what, in which direction, and where said shot landed. Let’s start with the landscape. If we create a landscape in two parts – a backdrop and foreground – we can make the foreground destructible so that when a missile explodes it damages part of the landscape. This is a common effect used in artillery games, and sometimes makes the gameplay more complicated as the battle progresses. In our example, we have a grass foreground overlaid on a mountain scene. We then need a cannon for each player. In this case, we’ve used a two-part image, one for the base and one for the turret, which means the latter can be rotated using the up and down keys.

Our homage to the artillery game genre. Fire away at your opponent, and hope they don’t hit back first.

For this code example, we can use the Python dictionary to store several bits of data about the game objects, including the Actor objects. This makes the data handling tidy and is quite similar to the way that JSON is used in JavaScript. We can use this method for the two cannons, the projectile, and an explosion object. As this is a two-player game, we’ll alternate between the two guns, allowing the arrow keys to change the angle of the cannon. When the SPACE bar is pressed, we call the firing sequence, which places the projectile at the same position as the gun firing it. We then move the missile through the air, reducing the speed as it goes and allowing the effects of gravity to pull it towards the ground.

We can work out whether the bullet has hit anything with two checks. The first is to do a pixel check with the foreground. If this comes back as not transparent, then it has hit the ground, and we can start an explosion. To create a hole in the foreground, we can write transparent pixels randomly around the point of contact and then set off an explosion animation. If we test for a collision with a gun, we may find that the bullet has hit the other player and after blowing up the tank, the game ends. If the impact only hit the landscape, though, we can switch control over to the other player and let them have a go.

So that’s your basic artillery game. But rest assured there are plenty of things to add – for example, wind direction, power of the shot, variable damage depending on proximity, or making the tanks fall into holes left by the explosions. You could even change the guns into little wiggly creatures and make your own homage to Worms.

Here’s Mark’s code for an artillery-style tank game. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code and assets, head here.

Get your copy of Wireframe issue 44

You can read more features like this one in Wireframe issue 44, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 44 for free in PDF format.

Wireframe #44, bringing the past and future of Worms to the fore.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 72% compared to newsstand pricing!

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Celebrating future engineers

We’re proud to show our support for This is Engineering Day, an annual campaign from the Royal Academy of Engineering to bring engineering to life for young people by showcasing its variety and creativity. This year’s #BeTheDifference theme focuses on the positive impact engineering can have on everyday life and on the world we live in. So what better way for us to celebrate than to highlight our community’s young digital makers — future engineers — and their projects created for social good!

A Coolest Projects participant, a future engineer we're celebrating on today's This is Engineering Day
So many Coolest Projects participants present tech projects they’ve created for social good.

We’re also delighted to have special guest Dr Lucy Rogers on our This Is Engineering–themed Digital Making at Home live stream today at 5.30pm GMT, where she will share insights into her work as a creative inventor.

Dr Lucy Rogers, here shown with soap bubbles, will be our guest our This is Engineering Day–themed live stream for young people. Photo credit: Karla Gowlett
Your young people can ask inventor Dr Lucy Rogers their questions live today! Photo credit: Karla Gowlett

Future engineers creating projects for social good

In July, we were lucky enough to have Dr Hayaatun Sillem, CEO of the Royal Academy of Engineering (RAEng), as a judge for Coolest Projects, our technology fair for young creators. Dr Hayaatun Sillem says, “Engineering is a fantastic career if you want to make a difference, improve people’s lives, and shape the future.”

A Coolest Projects participant, a future engineer we're celebrating on today's This is Engineering Day
Our community’s young digital makers want to #BeTheDifference

In total, the young people taking part in Coolest Projects 2020 online presented 560 projects, of which over 300 projects were made specifically for social good. Here’s a small sample from some future engineers across the world:

Carlos, Blanca & Mario from Spain created El ojo que te observa (The all-seeing eye)

“Our project is a virtual big eye doorman that detects if you wear a mask […] we chose this project because we like artificial intelligence and robotics and we wanted to help against the coronavirus.”

Momoka from Japan created AI trash can

“I want people to put trash in the correct place so I made this AI trash can. This AI trash can separates the trash. I used ML2 Scratch. I used a camera to help the computer learn what type of trash it is.”

Abhiy from the UK created Burglar Buster

“As we know, burglary cases are very frequent and it is upsetting for the families whose houses are burglarised and [can] make them feel fearful, sad and helpless. Therefore, I tried to build a system which will help everyone to secure their houses.”

Tune in today: This is Engineering-themed live stream with special guest Dr Lucy Rogers

Professor Lucy Rogers PhD is an inventor with a sense of fun! She is a Fellow of the RAEng, and RAEng Visiting Professor of Engineering:Creativity and Communication at Brunel University, London. She’s also a Fellow of the Institution of Mechanical Engineers. Adept at bringing ideas to life, from robot dinosaurs to mini mannequins — and even a fartometer for IBM! — she has developed her creativity and communication skills and shares her tricks and tools with others. 

Here Dr Lucy Rogers shares her advice for young people who want to get involved in engineering:

1. Create your own goal 

A goal or a useful problem will help you get over the steep learning curve that is inevitable in learning about new pieces of technology. Your goal does not have to be big: my first Internet of Things project was making a LED shine when the International Space Station was overhead.

2. Make your world a little better

To me “engineering” is really “problem-solving”. Find problems to solve. You may have to make something, program something, or do something. How can you make your own world a little better? 

3. Learn how to fail safely 

Learn how to fail safely: break projects into smaller pieces, and try each piece. If it doesn’t work, you can try again. It’s only at the end of a project that you should put all the “working” pieces together (and even then, they may not work nicely together!)

Dr Lucy Rogers will be joining our Digital Making at Home educators on our This is Engineering-themed live stream today at 5.30pm GMT.

This is your young people’s chance to be inspired by this amazing inventor! And we will take live questions via YouTube, Facebook, Twitter, and Twitch, so make sure your young people are able to get Dr Lucy’s live answers to their own questions about digital making, creativity, and all things engineering!

Engineering at home, right now

To get inspired about engineering right now, your young people can follow along step by step with Electricity generation, our brand-new, free digital making project on the impact of non-renewable energy on our planet!

Try out coding a Scratch project about electricity generation on  today's This is Engineering Day

While coding this Scratch project, learners input real data about the type and amount of natural resources that countries across the world use to generate electricity, and they then compare the results using an animated data visualisation.

The data we’ve made part of this project was compiled by the International Energy Agency, and we were also kindly given guidance by the Renewable Energy Foundation.

To find out more about This is Engineering Day, please visit  www.ThisisEngineering.org.uk.

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Designing Raspberry Pi 400

It’s been a journey, but it’s finally here, and I can talk about the secret Raspberry Pi 400 project! I’ll also try to cover some of the questions you asked following Eben’s announcement of Raspberry Pi 400 yesterday.

Four years in the making

It’s been over four years since the original idea of a Raspberry Pi inside a keyboard was discussed, before I even started working at Raspberry Pi Towers. Initially, the plan was for a kit with all the parts needed for people simply to open the box and get started by connecting the accessories to a “classic” credit-card sized Raspberry Pi. The challenge was that we needed a mouse and a keyboard: if we could manufacture a mouse and a keyboard, we could make a complete kit. How hard could it be? Then, within a day of our announcing our new keyboard and mouse, we saw a blog from someone who had milled out the keyboard and integrated a Raspberry Pi 3 Model A+ into it.

Our jaws dropped – we were impressed but we couldn’t say a word. Then others did the same with a Raspberry Pi Zero, and by that point we kind of expected that. We knew it was a good idea.

The keyboard and mouse were the big things we needed to sort out: once the quality control and supply chain were in place for those, we could move to fitting keyboard matrices to Raspberry Pi 400s, and achieve final assembly in Sony’s manufacturing facility in Wales. We had first planned to make a Raspberry Pi 3-based version, but it was clear that getting such a complex item into product wouldn’t happen until after we’d launched Raspberry Pi 4, and this would make the new product seem like a runner-up. So, instead, we started work on the Raspberry Pi 4-based version as soon as the design for that was finalised.

A fresh, new Raspberry Pi 4

The board inside the housing is essentially a Raspberry Pi 4 unit, but with a fresh PCB design. It has the same USB and Ethernet system as the Raspberry Pi 4, but one of the USB2.0 ports is dedicated to the keyboard.

Left-handed?

We have already seen a few comments about the USB ports being on the left side of the unit, and the fact that this makes the mouse cable cross over for most right-handed users. The PCB shape had to be defined early on so that the industrial designers could get on with the housing design, and I then stared endlessly at the PCB layout, trying to get one of the USB ports to route to the right side without wrecking the signal integrity of the memory or the HDMI; I could not find a way to do this. Left-handed folks and Bluetooth mouse-owners will be happy at least!

Micro HDMI

Raspberry Pi 400 has dual-band 802.11b/g/n/ac wireless LAN and Bluetooth 5.0. Like Raspberry Pi 4, it has dual micro HDMI output which achieves up to 4K video. It would have been be lovely to have had full-size HDMI connectors, but in order to achieve this we would have to remove other functions, or make a bulkier unit. However, the kit does come with a micro HDMI-to-HDMI cable to cheer you all up.

We kept the GPIO connector since it is loved so much by beginners and experts alike, and this is after all a Raspberry Pi – we want people to be able to use it for tinkering and prototyping. The HAT functionality works better with an extender cable, which you can buy from numerous websites.

1.8GHz!

Raspberry Pi 400 has the same circuit layout of the power management, processor, and memory as Raspberry Pi 4, but with one major difference: we’ve adjusted the operating point to 1.8GHz! And did I mention cooling? We’ve solved the cooling challenge so users don’t have to give this any thought. Raspberry Pi 400 contains a heat spreader that dissipates the heat across the whole unit, front and back, so that no part of it will feel too hot to touch. In fact, there is enough thermal margin to overclock it, if you’re so inclined.

Why not the Compute Module?

Some folks have asked us why we did not fit the Raspberry Pi Compute Module inside. The reason is that above a certain scale, it generally makes more sense to go with a custom PCB rather than a module with a carrier board. With hundreds of thousands of Raspberry Pi 400 units in the first instance, we are above that scale.

Turn it off and on again

We also have a feature that is completely new to Raspberry Pi products: an on/off button! Power off is achieved by pressing Fn+F10. This is a soft control that negotiates with Linux to shut down, so you don’t corrupt your memory card or your USB drive. Power can be restored by holding down F10 (or Fn+F10) for two seconds.

Prototyping

An early unit going through thermal analysis

A lot of love went into making this the best possible product we can manufacture, and it has been through extensive alpha testing and compliance testing. I thought I would show you the insides of a very early prototype. There are already some teardown videos online if you want to see how Raspberry Pi 400 is put together; it has not changed much from this:

Inside one of the first Raspberry Pi 400 units – 3D-printed and CNC-machined. ~£1500 each to build!

Raspberry Pi 400 kit

The official Raspberry Pi mouse has been a lovely product to have available where Raspberry Pi 400 is concerned, because now we can provide a complete kit of official matching Raspberry Pi parts that looks fantastic on your desk. The kit comes with the SD card already programmed and inserted, so on Christmas day, you just need to plug it into the family TV and start coding. No frantic searches for somewhere that sells memory cards!

Top view of a woman's hands using the Raspberry Pi 400 keyboard and official Raspberry Pi mouse

The kit includes:

  • Raspberry Pi 400 computer with choice of six keyboard countries (more to follow)
  • Official Raspberry Pi mouse
  • Raspberry Pi USB-C DC power source, with adaptors for each country
  • SD card ready-fitted in the unit with the latest software release installed
  • micro HDMI to HDMI cable
  • Jewel box to store the SD card
  • Fourth-edition Raspberry Pi Beginner’s Guide book with instructions for getting started with Raspberry Pi 400, as well as loads of things you can do with it

Ode to Commodore

Finally, a bit of fun to finish with. On Christmas morning 1985, I opened the polystyrene box of a Commodore 64 computer and the world switched on for me. It had the best games and the best sound, and it was easy to program. We think the combination of gaming and programming still works today, but we’ve come a long way since 1985. Here’s a chart to show how a Commodore 64 and a Raspberry Pi 400 compare.

I particularly like the benchmark increase for less than half the power. This makes Raspberry Pi 4 almost a million times more efficient at processing data.

We do hope this bring smiles to the faces of those fortunate enough to get one by Christmas. The factory has been running flat-out for the last two months building up stock – order yours soon though, since they’ll sell quickly! 

Special thanks to…

Alwyn Roberts, Andy Liu, Anthony Morton, Antti Silventoinen, Austin Su, Ben Stephens, Brendan Moran, Craig Wightman, Daniel Thompsett, David Christie, David John, David Lenton, Dominic Plunkett, Eddie Thorn, Gordon Hollingworth, Helen Marie, Jack Willis, James Adams, Jeremy Wang, Joe Whaley, Keiran Abraham, Keri Norris, Kuanhsi Ho, Laurent Le Mentec, Mandy Oliver, Mark Evans, Michael Howells, Mike Buffham, Mike Unwin, Peter Challis, Phil Elwell, Rhys Polley, Richard Jones, Rob Matthews, Roger Thornton, Sherman Liu, Simon Lewis, Simon Oliver, Tim Gover, Tony Jones, Viktor Lundström, Wu Hairong, and all the alpha testers and resellers who made Raspberry Pi 400 possible.

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Low-cost open source ventilator-ish device

Johnny made a low-cost ventilator-ish device, that is available on GitHub:

In the event that COVID-19 hospitalizations exhaust the availability of FDA approved ventilators. This project documents the process of converting a low-cost CPAP (Continuous Positive Airway Pressure) blower into a rudimentary non-invasive pressure support ventilator that could help with breathing during respiratory distress. It’s an evolving project, but in it’s current form, it most aligned with the definition of a non-invasive pressure support BiPAP ventilator.
This same project can also be used to create a reasonable low-cost Powered Air Purifying Respirator (PAPR) with filter adapter and mask.

See the full post on Johnny Chung Lee’s project blog.

Check out the video after the break.

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Raspberry Pi 400: the $70 desktop PC

Raspberry Pi has always been a PC company. Inspired by the home computers of the 1980s, our mission is to put affordable, high-performance, programmable computers into the hands of people all over the world. And inspired by these classic PCs, here is Raspberry Pi 400: a complete personal computer, built into a compact keyboard.

Raspberry Pi 4, which we launched in June last year, is roughly forty times as powerful as the original Raspberry Pi, and offers an experience that is indistinguishable from a legacy PC for the majority of users. Particularly since the start of the COVID-19 pandemic, we’ve seen a rapid increase in the use of Raspberry Pi 4 for home working and studying.

A front view of the Raspberry Pi keyboard

But user friendliness is about more than performance: it can also be about form factor. In particular, having fewer objects on your desk makes for a simpler set-up experience. Classic home computers – BBC Micros, ZX Spectrums, Commodore Amigas, and the rest – integrated the motherboard directly into the keyboard. No separate system unit and case; no keyboard cable. Just a computer, a power supply, a monitor cable, and (sometimes) a mouse.

Raspberry Pi 400

We’ve never been shy about borrowing a good idea. Which brings us to Raspberry Pi 400: it’s a faster, cooler 4GB Raspberry Pi 4, integrated into a compact keyboard. Priced at just $70 for the computer on its own, or $100 for a ready-to-go kit, if you’re looking for an affordable PC for day-to-day use this is the Raspberry Pi for you.

Buy the kit

The Raspberry Pi 400 Personal Computer Kit is the “Christmas morning” product, with the best possible out-of-box experience: a complete PC which plugs into your TV or monitor. The kit comprises:

  • A Raspberry Pi 400 computer
  • Our official USB mouse
  • Our official USB-C power supply
  • An SD card with Raspberry Pi OS pre-installed
  • A micro HDMI to HDMI cable
  • The official Raspberry Pi Beginner’s Guide

At launch, we are supporting English (UK and US), French, Italian, German, and Spanish keyboard layouts, with (for the first time) translated versions of the Beginner’s Guide. In the near future, we plan to support the same set of languages as our official keyboard.

Buy the computer

Saving money by bringing your own peripherals has always been part of the Raspberry Pi ethos. If you already have the other bits of the kit, you can buy a Raspberry Pi 400 computer on its own for just $70.

A close up of the left-hand keys of the Raspberry Pi 400

Buy the book

To accompany Raspberry Pi 400, we’ve released a fourth edition of our popular Raspberry Pi Beginner’s Guide, packed with updated material to help you get the most out of your new PC.

You can buy a copy of the Beginner’s Guide today from the Raspberry Pi Press store, or download a free PDF.

Where to buy Raspberry Pi 400

UK, US, and French Raspberry Pi 400 kits and computers are available to buy right now. Italian, German, and Spanish units are on their way to Raspberry Pi Approved Resellers, who should have them in stock in the next week.

We expect that Approved Resellers in India, Australia, and New Zealand will have kits and computers in stock by the end of the year. We’re rapidly rolling out compliance certification for other territories too, so that Raspberry Pi 400 will be available around the world in the first few months of 2021.

Of course, if you’re anywhere near Cambridge, you can head over to the Raspberry Pi Store to pick up your Raspberry Pi 400 today.

What does everyone else think?

We let a handful of people take an early look at Raspberry Pi 400 so they could try it out and pull together their thoughts to share with you. Here’s what some of them made of it.

Simon Martin, who has spent the last couple of years bringing Raspberry Pi 400 to life, will be here tomorrow to share some of the interesting technical challenges that he encountered along the way. In the meantime, start thinking about what you’ll do with your Raspberry Pi PC.

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App note: Termination recommendations for single-ended oscillator driving single or multiple Loads

Proper clock signal terminations app note from SiTime. Link here (PDF)

Clock signals with fast edges see traces on Printed Circuit Boards (PCB) as transmission lines rather than simple wire connections. If the length of PCB trace exceeds certain limit it requires matching of the trace impedance to one or both of the source and load impedances. Impedance mismatch causes signal reflections travelling back and forth the transmission line causing signal distortions such as ringing, overshoots, and undershoots.

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