App note: Is the lowest forward voltage drop of real schottky diodes always the best choice?

App note from IXYS about the pros and cons of different forward voltage drop of real shottky diodes. Link here (PDF)

According to the thermionic emission model, pure Schottky barriers exhibit a forward voltage drop, which decreases linearly as the barrier height diminishes; whereas the reverse current increases exponentially as the barrier height decreases. Consequently, there exists an optimum barrier height, which can minimize the sum of forward and reverse power dissipation for a particular application.
However, discussions with the users of Schottky diodes reveal that they do not search for the minimum of forward and reverse power dissipation but always for the minimum forward voltage drop. Values of reverse current are very rarely asked for. One must know how the Schottky diode is being applied in order to objectively select the most appropriate part.

from Dangerous Prototypes https://ift.tt/35yaled

App note: Voltage vs. output speed vs. torque on DC motors

App note from Precision Microdrives about DC motor capabilities and their uses. Link here

Why Change Torque?
The most obvious benefit of varying the torque is to maintain a constant speed when the motor’s load varies, keeping in mind the interdependent nature of speed, torque, and voltage.

Although this example may be outdated, audio cassettes are a great way of explaining how some applications need to vary the torque to match a changing load. As the cassette plays and the audio tape moves from one spindle to the other, the driving motor will experience a change in load. However, the playback must remain at a constant speed throughout – otherwise the audio pitch would be affected.

Why Change Speed?
The ability to vary motor speed whilst maintaining a steady torque is essential to many applications for a variety of reasons.

An example of an application that requires a variable speed and steady torque is an audio CD player as it is commonly observed that the CD will rotate faster at certain points than others. This is because the information is stored in spiralled circular tracks on the disk and the length/circumference of the track is directly proportional to the amount of information stored on them. This means that the speed must be decreased as the laser is reading from the outermost tracks because there is more information per revolution. Inversely, the speed is increased as the laser reads from the innermost tracks as the spiral circumferences are smaller and therefore contain less information per revolution.

from Dangerous Prototypes https://ift.tt/3mlwLq1

Join us for TEDWomen 2020: Fearless on November 12

TEDWomen 2020 is nearly here! The day-long conference will take place on November 12 via TED’s new virtual conference platform. TEDWomen attendees will experience TED’s signature talks as well as an array of live, interactive sessions, community “idea dates,” small-group speaker Q&As and more. The talks featured in the program have been developed in collaboration with an incredible group of TEDx organizers from Lagos, Nigeria; Port of Spain, Trinidad and Tobago; Montreal, Canada; Colombo, Sri Lanka; and Sydney, Australia. TEDWomen will celebrate and amplify dynamic, multi-dimensional ideas from these communities and around the world.

In the midst of uncertainty, the greatest peril is to retreat or become immobilized. At TEDWomen, we’ll hear from bold leaders who are stepping forward and taking action.

TEDWomen 2020 speakers and performers include:

  • Kluane Adamek, Assembly of First Nations Yukon Regional Chief
  • Kylar W. Broadus, Human and civil rights attorney and advocate
  • Kemi DaSilva-Ibru, Women’s health specialist
  • Adie Delaney, Educator and performer
  • Elizabeth Diller, Architect, artist and designer
  • Julia Gillard, 27th Prime Minister of Australia
  • Jamila Gordon, AI advocate
  • María Teresa Kumar, Civic leader
  • JayaShri Maathaa, Monk
  • Megan McArthur, NASA astronaut
  • Madison McFerrin, Singer and songwriter
  • Renee Montgomery, WNBA champion and activist
  • Ngozi Okonjo-Iweala, Economist and international development expert
  • Angélique Parisot-Potter, Legal and business integrity leader
  • Sophie Rose, Infectious disease researcher
  • Apiorkor Seyiram Ashong-Abbey, Poet and author
  • Gloria Steinem, Feminist activist and writer
  • Sviatlana Tsikhanouskaya, Politician
  • Tracy Young, Builder
  • View the full speaker lineup

TED has partnered with a number of organizations to support its mission and contribute to the idea exchange at TEDWomen 2020. These organizations are collaborating with the TED team on innovative ways to engage a virtual audience and align their ideas and perspectives with this year’s programming. This year’s partners include: Boston Consulting Group, Dove Advanced Care Antiperspirant, Project Management Institute and the U.S. Air Force.

TEDWomen 2020 is taking place on November 12, 11am – 6pm ET. TEDWomen applications will be accepted until 9am ET, November 9 (or until sold out). Learn more and apply now!

from TED Blog https://ift.tt/3jqxiVR

Symbiotic: The talks of TED@BCG 2020

Is TikTok changing the way we work and learn? Qiuqing Tai talks about the rise of short-form videos at TED@BCG on October 21, 2020. (Photo courtesy of TED)

How can we make advances in technology that don’t require massive job losses? Work with nature to protect both the planet and humanity? Ensure all people are treated equitably? In a day of talks, interviews and performances, 17 speakers and performers shared ideas about a future in which people, technology and nature thrive interdependently.

The event: TED@BCG: Symbiotic is the ninth event TED and Boston Consulting Group have partnered around to bring leaders, innovators and changemakers to the stage to share ideas for solving society’s biggest challenges. Hosted by TED’s Corey Hajim along with BCG’s Seema Bansal, Rocío Lorenzo and Vinay Shandal, with opening remarks from Rich Lesser, CEO of BCG.

Music: The group Kolinga, fronted by lead singer Rébecca M’Boungou, perform the original song “Nguya na ngai” — a stunning rendition that’s equal parts music, poetry and dance.

The talks in brief:

Qiuqing Tai, video visionary

Big idea: Short-form videos — 60 seconds or less, made and shared on apps like TikTok, Snapchat and Instagram — are changing the way we work, communicate and learn.

How? More than 1.5 billion people around the world regularly watch short videos, and more than half of them are under the age of 24, says Qiuqing Tai. This bite-sized content is quickly becoming the new normal, with people turning to it not only for entertainment but also to discover new interests and skills. Meanwhile, businesses use short-form videos to find new customers and diversify their audiences. In 2019, Tai led a research study with TikTok, finding that the platform’s short-form content generated an estimated $95 billion in goods and services sold, and helped create 1.2 million jobs globally. There has also been an explosion in short-form educational content, as social enterprises and education startups experiment with 15-second videos for people who want to learn on the fly. There are valid concerns about this young medium, Tai admits — data privacy, the addictive nature of the format, the lack of contextual nuance — but, with the right investment and policymaking, she believes the benefits will ultimately outweigh the drawbacks.


Matt Langione, quantum advocate

Big idea: If not traditional supercomputers, what technology will emerge to arm us against the challenges of the 21st century?

What will it be? For nearly a century, we’ve relied on high-performance computers to meet critical, complex demands — from cracking Nazi codes to sequencing the human genome — and they’ve been getting smaller, faster and better, as if by magic. But that magic seems to be running out due to the physical limitations of the traditional supercomputer, says Matt Langione — and it’s time to look to newer, subatomic horizons. Enter quantum computing: an emerging hyper-speed solution for the urgent challenges of our time, like vaccine development, finance and logistics. Langione addresses fundamental questions about this burgeoning technology — How does it work? Do we really need it? How long until it’s available? — with a goal in mind: to disperse any doubts about investing in quantum computing now rather than later, for the sake of lasting progress for business and society at large. “The race to a new age of magic and supercomputing is already underway,” he says. “It’s one we can’t afford to lose.”


Ajay Banga, CEO of Mastercard, discusses financial inclusion and how to build a more equitable economy. He speaks with TED current affairs curator Whitney Pennington Rodgers at TED@BCG on October 21, 2020. (Photo courtesy of TED)

Ajay Banga, CEO of Mastercard

Big idea: Let’s introduce those who are un-banked or under-banked into the banking system via a mobile, digital economy.

How? Roughly two billion people don’t have access to banks or services like credit, insurance and investment — or even a way to establish a financial identity. These people must rely solely on cash, which can be dangerous and prone to fraud by middlemen (and costs about 1.2 percent of a nation’s GDP to produce). As an advocate of “financial inclusion,” Mastercard CEO Ajay Banga believes that banks, fintech and telecom companies, governments and merchants can build a new, more equitable economy that relies on digital transactions rather than cash. How would its users benefit? As an example, a grocer may not be able to afford supplies for the week if she’s paying cash, but with a mobile payment system, she could build enough of a transaction history to establish credit, and with enough credit, she could build a “financial identity.” Such identities could revolutionize everything from small business to distributing aid — all using tech that’s already in place, and that doesn’t require a smartphone.


Nimisha Jain, commerce aficionado

Big idea: For Nimisha Jain, shopping was once an activity full of excitement, friends, family and trusted sellers. But for many like her in emerging markets worldwide, online shopping is intimidating and, frankly, inhuman, full of mistrust for unscrupulous sellers and mysterious technology. Is there a way for online sellers to build genuine human interactivity into virtual shopping, at scale?

How? Fortunately, it’s possible to combine the convenience of online shopping with a personalized experience in what Jain calls “conversational commerce,” and some companies are doing exactly this — like Meesho in India, which allows shoppers to interact with the same person every time they shop. Over time, the agent learns what you like, when you would like it and, once trusted, will fill your shopping cart with unexpected items. But this model is not only for the developing world; Jain’s research shows that customers in the West also like this concept, and it might someday transform the way the world shops. 


Emily Leproust, DNA synthesizer

Big idea: We need to rethink what modern global sustainability looks like — and pursue a new kind of environmentalism.

How? By working with the environment, rather than against it. As it stands, nature has been adapting and reacting to the presence of human developments, just like we’ve been adapting and reacting to nature’s changing climate, says Leproust — and we must course-correct before we destroy each other. She advocates for a path paved by synthetic biology and powered by DNA. Embracing the potential of biological innovation could help across the board, but Leproust singles out three critical areas: health, food and materials. If we focus our energy on pursuing sustainable outcomes — like lab-developed insulin, engineering foods to be immune to disease and harnessing the potential of spider silk — human civilization and the natural world could thrive in tandem without worry.


“Technology is fundamentally infiltrating every aspect of our daily lives, transforming everything from how we work to how we fall in love. Why should sports be any different?” asks esports expert William Collis. He speaks at TED@BCG on October 21, 2020. (Photo courtesy of TED)

William Collis, esports expert

Big idea: We revere traditional athletic prowess, but what about the skills and talent of a different sort of athlete?

What do you mean? Video games should no longer be considered children’s play, says esports expert William Collis. They’ve grown into a multibillion-dollar sporting phenomenon — to the point where traditional sport stars, from David Beckham to Shaquille O’Neal, are investing in competitive games like Fortnite, League of Legends and Rocket League. It takes real skill to be good at these video games, reminds Collis, which he breaks down into three main categories: mechanical (much like playing an instrument), strategic (equivalent to tactical choices of chess) and leadership. Beyond that, being a pro-gamer requires adaptability, creativity and unconventional thinking. Collis’s message is simple: respect the game and the valuable traits developed there, just as you would any other sport.


Bas Sudmeijer, carbon capture advisor

Big idea: Carbon capture and storage — diverting emissions before they hit the atmosphere and burying them back in the earth — is not new, but analysts like Bas Sudmeijer think it could both contribute to the fight against climate change and allow big polluters (who are also big employers) to stay in business. But for carbon capture to make a significant contribution to emission reductions, we must spend 110 billion dollars a year for the next 20 years.

How can we offset this enormous cost? Sudmeijer believes that “carbon networks” — clusters of polluters centered around potential underground carbon sinks — could solve the economic barriers to this promising technology, if they’re created in conjunction with aggressive regulation to make polluting more expensive. And the clock is ticking: current carbon capture operations trap only .1 percent of greenhouse gases, and we need to increase that number 100- to 200-fold in order to slow global warming. Fortunately, we have a historical model for this — the push to supply gas to Europe after World War II, carried out in a similar time frame during a period of similar economic stress.


“One of the best ways to safeguard democracy is to expose everyone to each other’s stories, music, cultures and histories,” says Mehret Mandefro. She speaks at TED@BCG on October 21, 2020. (Photo courtesy of TED)

Mehret Mandefro, physician, filmmaker

Big idea: A robust and well-funded creative industry drives economic and democratic growth. A thriving creative industry isn’t just “a nice thing to have” — it’s a democratic necessity. 

How? With a median age of about 19, Ethiopia’s youth are rapidly graduating into a labor market with an astronomical 19-percent unemployment rate and few opportunities. To create enough good-paying jobs for its expanding workforce, Mehret Mandefro says the government should expand the creative sector. She says that putting culture on the agenda could boost industries like tourism and drive the country’s overall economic growth. The creative industry also plays an important social and democratic role. In a period of strained relations and rising ethnic divisions, society must make a choice, she says: “From my perspective, the country can go one of two ways: either down a path of inclusive, democratic participation, or down a more divisive path of ethnic divisions.” For Mandefro, the answer is clear. She sees the arts as the best way for people to share in one another’s culture, where music, fashion, film, theater and design create connection and understanding between groups and strengthen democratic bonds. “One of the best ways to safeguard democracy is to expose everyone to each other’s stories, music, cultures and histories,” she says.


Antoine Gourévitch, deep tech diver

Big idea: The next chapter in the innovation story, driving us into the future, is the potential and promise of deep tech.

How? Antoine Gourévitch believes deep tech — tangible, intentional collaboration at the crossroads of emerging technologies (think synthetic biology, quantum programming and AI) — will change the ways we produce material, eat, heal and beyond. Deep tech ventures — one of the most notable examples being SpaceX — focus on fundamental issues by first identifying physical constraints that industries often encounter, and then solve them with a potent combination of science, engineering and design thinking. Thousands of companies and start-ups like this currently exist worldwide, sharing an ethos of radical possibility. They’re governed by four rules: be problem-oriented, not technology-focused; combine, intersect and converge; adopt a design thinking approach, powered by deep tech; and adopt an economical design-to-cost approach. In understanding these guidelines, Gourévitch wants us to embrace the idea that innovation requires rethinking, and that this cross-disciplinary approach could offer a revolution in making what seemed impossible, possible. 


Tilak Mandadi, empathy advocate

Big Idea: Empathy training should be part of workplace culture. Here are three ways to implement it. 

How? After the trauma of losing his daughter, Tilak Mandadi’s decision to return to work wasn’t easy — but his journey back ended up providing unexpected support in processing his grief. At first, he was full of self-doubt and sadness, feeling as if he was living in two completely different worlds: the personal and the professional. But over time, his coworkers’ friendship and purpose-driven work helped transform his exhaustion and isolation, shedding light on the role empathy plays in a healthy work culture — both for people suffering with loss and those who aren’t. Mandadi offers three ways to foster this kind of environment: implement policies that support healing (like time away from work); provide return-to-work therapy for employees who are dealing with grief; and provide empathy training for all employees so that they know how to best support each other. Empathy can be a learned behavior, he says, and sometimes asking “What would you like me to do differently to help you?” can make all the difference. 


Documentary photographer Olivia Arthur presents her work at TED@BCG, including this photo of Pollyanna, who lost her leg in an accident at the age of two and now dances with the aid of a blade prosthesis. (Photo courtesy of Olivia Arthur)

Olivia Arthur, documentary photographer

Big idea: Across the world, people are merging technology with the human body in remarkable ways, sparking radical meditations on what it means to be human.

How? Through photography, Olivia Arthur intimately examines the intersection of humanity and technology, capturing the resilience and emotional depths of the human body. In her latest project, she collaborated with amputees who have integrated technology into their bodies and researchers who have invented robots with strikingly human traits. Inspired in part by photographer Eadweard Muybridge, Arthur focused on gait, balance and motion in both human and machine subjects. These included Pollyanna, a dancer who mastered the delicate skill of balance while using a blade prosthesis; Lola, a humanoid robot who confidently navigated an obstacle course yet looked most human when turned off; and Alex Lewis, a quadruple amputee who challenges perceptions of humanity’s limitations. Arthur describes her photos as studies of our evolution, documenting how technology has catalyzed a profound shift in how we understand, enhance and define the human body. 


Wealth equity strategist Kedra Newsom Reeves explores the origins and perpetuation of the racial wealth gap in the US — and four ways financial institutions can help narrow it. She speaks at TED@BCG on October 21, 2020. (Photo courtesy of TED)

Kedra Newsom Reeves, wealth equity strategist

Big idea: We need to narrow the racial wealth gap in the United States. Financial institutions can help.

How? As last reported by the US federal government, the median wealth for a white family in the United States was 171,000 dollars, and the median wealth for a Black family was just 17,000 dollars — a staggering tenfold difference. During a global pandemic in which inequities across finance, health care, education and criminal justice have been laid bare, Kedra Newsom Reeves says that we must make progress towards reducing this gap. She tells the story of her great-great-grandfather, who was born into slavery, and how it took four generations for her family to accumulate enough wealth to purchase a house. Along the way, she says, a range of policies purposefully excluded her family — along with marginalized communities across the country — from building wealth. Now, financial institutions can help undo that damage. She offers four critical actions: ensure more people have bank accounts; increase awareness of checking and savings accounts specifically made for low-income communities; find alternative ways to establish creditworthiness, and then lend more credit to marginalized groups; and invest, support and promote Black-owned business, particularly by increasing the amount of venture capital that goes to Black founders.


Ishan Bhabha, constitutional lawyer

Big idea: Debate can broaden perspectives, spark creativity and catalyze human progress, so instead of censoring controversial speech, private entities should create pathways for productive discussion.

Why? In the United States, the First Amendment guarantees the right to free speech but only protects citizens against censorship by the government — not by private entities. But just because a conference center, university or social media platform can ban speech on their own turf doesn’t mean they should, says Ishan Bhabha. When faced with the decision to allow or prohibit meritless speech, he argues that more often than not, more speech is better. Instead of restricting speech, groups should err on the side of allowing it and work to create an open dialogue. “Ideas that have little to no value should be met with arguments against it,” he says. Private groups should protect against hate speech that can cause lasting damage or even violence but should respond responsibly to other ideological speech and mediate discussion, which can promote productive disagreement and lead to a valuable exchange of ideas. Universities, for instance, can offer students mediated discussion groups where they can openly try on new ideas without the threat of sanction. Twitter now responds to unsubstantiated posts on their platform by flagging content as either misleading, deceptive or containing unverified information and provides links to verified sources where users can find more information. Bhabha argues that these practices add to a rich and vigorous discussion with the potential to improve the arena of debate by raising the standard.


Johanna Benesty, global health strategist

Big idea: Discovering an effective COVID-19 vaccine is just the first step in ending the pandemic. After that, the challenge lies in ensuring everyone can get it.

Why? We’ve been thinking of vaccine discovery as the holy grail in the fight against COVID-19, says Johanna Benesty, but an equally difficult task will be providing equitable access to it. Namely, once a vaccine is found to be effective, who gets it first? And how can we make sure it’s safely distributed in low-income communities and countries, with less robust health care systems? Benesty suggests that vaccine developers consider the constraints of lesser health care systems from the outset, building cost management into their research and development activities. In this way, they can work to ensure vaccines are affordable, effective across all populations (like at-risk people and pregnant women) and that can be distributed in all climates (from temperature-controlled hospitals to remote rural areas) at scale. It’s the smart thing to do, Benesty says: if COVID-19 exists anywhere in the world, we’re all at risk, and the global economy will continue to sputter. “We need all countries to be able to crush the pandemic in sync,” she says.


Rosalind G. Brewer, COO of Starbucks, explores how to bring real, grassroots racial changes to boardrooms and communities alike. She speaks with TED current affairs curator Whitney Pennington Rodgers at TED@BCG on October 21, 2020. (Photo courtesy of TED)

Rosalind G. Brewer, COO of Starbucks

Big idea: When companies think of DEI — diversity, equality, inclusion — they too often think of it as a numbers game that’s about satisfying quotas instead of building relationships with those who have traditionally been excluded from the corporate conversation. Rosalind G. Brewer believes that the current moment of racial consciousness is an “all-in” opportunity for hidebound leadership to step out of their comfort zones and bring real, grassroots racial changes to boardrooms and communities alike.

How? With Black Lives Matter in the headlines, the pandemic illuminating inequalities in health care and income, and so many brands engaging in “performative justice” PR campaigns, it’s a crucial time to not only include more BIPOC in the corporate workplace, but also to listen to their voices. As brands like Starbucks diversify and absorb the stories of their new partners, Brewer believes they will do far more than satisfy quotas — they will nurture future leaders, open minds and bring ground-up change to communities.


Kevin Roose, technology journalist

Big idea: By leaning into our creativity, empathy and other human skills, we can better collaborate with smart machines and “future-proof” our jobs.

How? Artificial intelligence has become smarter, faster and even more integrated into our lives and careers: algorithms have been trained to write financial articles, detect diseases and proofread legal documents at speeds and scales dramatically faster than any individual human could. But this doesn’t necessarily mean robots will inevitably replace us at work, says Kevin Roose. While an algorithm may be able to scan exams and detect disease faster than a human, a machine can’t replace a doctor’s comforting bedside manner. Instead of trying to compete with smart technologies at what they do best, we need to invest in developing the skills that machines aren’t capable of — creativity, compassion, adaptability and critical thinking.

from TED Blog https://ift.tt/2TmxHxK

Formative assessment in the computer science classroom

In computing education research, considerable focus has been put on the design of teaching materials and learning resources, and investigating how young people learn computing concepts. But there has been less focus on assessment, particularly assessment for learning, which is called formative assessment. As classroom teachers are engaged in assessment activities all the time, it’s pretty strange that researchers in the area of computing and computer science in school have not put a lot of focus on this.

Shuchi Grover

That’s why in our most recent seminar, we were delighted to hear about formative assessment — assessment for learning — from Dr Shuchi Grover, of Looking Glass Ventures and Stanford University in the USA. Shuchi has a long track record of work in the learning sciences (called education research in the UK), and her contribution in the area of computational thinking has been hugely influential and widely drawn on in subsequent research.

Two types of assessment

Assessment is typically divided into two types:

  1. Summative assessment (i.e. assessing what has been learned), which typically takes place through examinations, final coursework, projects, etcetera.
  2. Formative assessment (i.e. assessment for learning), which is not aimed at giving grades and typically takes place through questioning, observation, plenary classroom activities, and dialogue with students.

Through formative assessment, teachers seek to find out where students are at, in order to use that information both to direct their preparation for the next teaching activities and to give students useful feedback to help them progress. Formative assessment can be used to surface misconceptions (or alternate conceptions) and for diagnosis of student difficulties.

Venn diagram of how formative assessment practices intersect with teacher knowledge and skills
Click to enlarge

As Shuchi outlined in her talk, a variety of activities can be used for formative assessment, for example:

  • Self- and peer-assessment activities (commonly used in schools).
  • Different forms of questioning and quizzes to support learning (not graded tests).
  • Rubrics and self-explanations (for assessing projects).

A framework for formative assessment

Shuchi described her own research in this topic, including a framework she has developed for formative assessment. This comprises three pillars:

  1. Assessment design.
  2. Teacher or classroom practice.
  3. The role of the community in furthering assessment practice.
Shuchi Grover's framework for formative assessment
Click to enlarge

Shuchi’s presentation then focused on part of the first pillar in the framework: types of assessments, and particularly types of multiple-choice questions that can be automatically marked or graded using software tools. Tools obviously don’t replace teachers, but they can be really useful for providing timely and short-turnaround feedback for students.

As part of formative assessment, carefully chosen questions can also be used to reveal students’ misconceptions about the subject matter — these are called diagnostic questions. Shuchi discussed how in a classroom setting, teachers can employ this kind of question to help them decide what to focus on in future lessons, and to understand their students’ alternate or different conceptions of a topic. 

Formative assessment of programming skills

The remainder of the seminar focused on the formative assessment of programming skills. There are many ways of assessing developing programming skills (see Shuchi’s slides), including Parsons problems, microworlds, hotspot items, rubrics (for artifacts), and multiple-choice questions. As an MCQ example, in the figure below you can see some snippets of block-based code, which students need to read and work out what the outcome of running the snippets will be. 

Click to enlarge

Questions such as this highlight that it’s important for learners to engage in code comprehension and code reading activities when learning to program. This really underlines the fact that such assessment exercises can be used to support learning just as much as to monitor progress.

Formative assessment: our support for teachers

Interestingly, Shuchi commented that in her experience, teachers in the UK are more used to using code reading activities than US teachers. This may be because code comprehension activities are embedded into the curriculum materials and support for pedagogy, both of which the Raspberry Pi Foundation developed as part of the National Centre for Computing Education in England. We explicitly share approaches to teaching programming that incorporate code reading, for example the PRIMM approach. Moreover, our work in the Raspberry Pi Foundation includes the Isaac Computer Science online learning platform for A level computer science students and teachers, which is centered around different types of questions designed as tools for learning.

All these materials are freely available to teachers wherever they are based.

Further work on formative assessment

Based on her work in US classrooms researching this topic, Shuchi’s call to action for teachers was to pay attention to formative assessment in computer science classrooms and to investigate what useful tools can support them to give feedback to students about their learning. 

Advice from Shuchi Grover on how to embed formative assessment in classroom practice
Click to enlarge

Shuchi is currently involved in an NSF-funded research project called CS Assess to further develop formative assessment in computer science via a community of educators. For further reading, there are two chapters related to formative assessment in computer science classrooms in the recently published book Computer Science in K-12 edited by Shuchi.

There was much to take away from this seminar, and we are really grateful to Shuchi for her input and look forward to hearing more about her developing project.

Join our next seminar

If you missed the seminar, you can find the presentation slides and a recording of the Shuchi’s talk on our seminars page.

In our next seminar on Tuesday 3 November at 17:00–18:30 BST / 12:00–13:30 EDT / 9:00–10:30 PT / 18:00–19:30 CEST, I will be presenting my work on PRIMM, particularly focusing on language and talk in programming lessons. To join, simply sign up with your name and email address.

Once you’ve signed up, we’ll email you the seminar meeting link and instructions for joining. If you attended this past seminar, the link remains the same.

The post Formative assessment in the computer science classroom appeared first on Raspberry Pi.

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New Chair and Trustees of the Raspberry Pi Foundation

I am delighted to share the news that we have appointed a new Chair and Trustees of the Raspberry Pi Foundation. Between them, they bring an enormous range of experience and expertise to what is already a fantastic Board of Trustees, and I am really looking forward to working with them.

New Chair of the Board of Trustees: John Lazar 

John Lazar has been appointed as the new Chair of the Board of Trustees. John is a software engineer and business leader who is focused on combining technology and entrepreneurship to generate lasting positive impact.

Formerly the Chairman and CEO of Metaswitch Networks, John is now an angel investor, startup mentor, non-executive chairman and board director, including serving as the Chair of What3Words. He is a Fellow of the Royal Academy of Engineering and played an active role in developing the programme of study for England’s school Computer Science curriculum. John has also spent many years working on tech-related non-profit initiatives in Africa and co-founded Enza Capital, which invests in early-stage African technology companies that solve pressing problems.

John takes over the Chair from David Cleevely, who has reached the end of his two three-year terms as Trustee and Chair of the Foundation. David has made a huge contribution to the Foundation over that time, and we are delighted that he will continue to be involved in our work as one of the founding members of the Supporters Club.

New Trustees: Amali de Alwis, Charles Leadbeater, Dan Labbad

Alongside John, we are welcoming three new Trustees to the Board of Trustees: 

  • Amali de Alwis is the UK Managing Director of Microsoft for Startups, and is the former CEO of Code First: Girls. She is also a Board member at Ada National College for Digital Skills, sits on the Diversity & Inclusion Board at the Institute of Coding, is an Advisory Board member at the Founders Academy, and was a founding member at Tech Talent Charter.
  • Charles Leadbeater is an independent author, a social entrepreneur, and a leading authority on innovation and creativity. He has advised companies, cities, and governments around the world on innovation strategy and has researched and written extensively on innovation in education. Charles is also a Trustee of the Paul Hamlyn Foundation.
  • Dan Labbad is Chief Executive and Executive Member of the Board of The Crown Estate. He was previously at Lendlease, where he was Chief Executive Officer of Europe from 2009. Dan is also a Director of The Hornery Institute and Ark Schools.

New Member: Suranga Chandratillake 

I am also delighted to announce that we have appointed Suranga Chandratillake as a Member of the Raspberry Pi Foundation. Suranga is a technologist, entrepreneur, and investor.

Suranga Chandratillake

He founded the intelligent search company blinkx and is now a General Partner at Balderton Capital. Suranga is a Fellow of the Royal Academy of Engineering and a World Economic Forum Young Global Leader, and he serves on the UK Government’s Council for Science and Technology.

What is a Board of Trustees anyway? 

As a charity, the Raspberry Pi Foundation is governed by a Board of Trustees who is ultimately responsible for what we do and how we are run. It is the Trustees’ job to make sure that we are focused on our mission, which for us means helping more people learn about computing, computer science, and related subjects. The Trustees also have all the usual responsibilities of company directors, including making sure that we use our resources effectively. As Chief Executive, I am accountable to the Board of Trustees. 

We’ve always been fortunate to attract the most amazing people to serve as Trustees and, as volunteers, they are incredibly generous with their time, sharing their expertise and experience on a wide range of issues. They are an important part of the team. Trustees serve for up to two terms of three years so that we always have fresh views and experience to draw on.

How do you appoint Trustees? 

Appointments to the Board of Trustees follow open recruitment and selection processes that are overseen by the Foundation’s Nominations Committee, supported by independent external advisers. Our aim is to appoint Trustees who bring different backgrounds, perspectives, and lived experience, as well as a range of skills. As with all appointments, we consider diversity at every aspect of the recruitment and selection processes.

Formally, Trustees are elected by the Foundation’s Members at our Annual General Meeting. This year’s AGM took place last week on Zoom. Members are also volunteers, and they play an important role in holding the Board of Trustees to account, helping to shape our strategy, and acting as advocates for our mission.

You can see the full list of Trustees and Members on our website.

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Designing the Raspberry Pi Compute Module 4

Raspberry Pi Compute Module 4 designer Dominic Plunkett was kind enough to let us sit him down for a talk with Eben, before writing up his experience of bringing our latest board to life for today’s blog post. Enjoy.

When I joined Raspberry Pi, James, Eben and Gordon already had some ideas on the features they would like to see on the new Compute Module 4, and it was down to me to take these ideas and turn them into a product. Many people think design is a nice linear process: ideas, schematics, PCB, and then final product. In the real world the design process isn’t like this, and to get the best designs I often try something and iterate around the design loop to get the best possible solution within the constraints.

Form factor change

Previous Compute Modules were all in a 200-pin SODIMM form factor, but two important considerations pushed us to think about moving to a different form factor: the need to expose useful interfaces of the BCM2711 that are not present in earlier SoCs, and the desire to add extra components, which meant we needed to route tracks differently to make space on the PCB for the additional parts.

Breaking out BCM2711’s high-speed interfaces

We knew we wanted to get the extra features of the BCM2711 out to the connector so that users could make use of them in their products. High-speed interfaces like PCIe and HDMI are so fast coming out of the BCM2711 that they need special IO pins that can’t also support GPIO: if we were to change the functionality of a GPIO pin to one of the new high-speed signals, this would break backwards compatibility.

We could consider adding some sort of multiplexer to swap between old and new functionality, but this would cost space on the PCB, as well as reducing the integrity of the fast signals. This consideration alone drives the design to a new pinout. We could have tried to use one of the SODIMM connectors with extra pins; while this would give a board with similar dimensions to the existing Compute Modules, it too would break compatibility.

Compute Module 4 mounted on the IO Board
Compute Module 4 mounted on the IO Board

PCB space for additional components

We also wanted to add extra items to the PCB, so PCB space to put the additional parts was an important consideration. If you look carefully at a Compute Module 3 you can see a lot of tracks carrying signals from one side of the SoC to the pins on the edge connector. These tracks take up valuable PCB space, preventing components being fitted there. We could add extra PCB layers to move these tracks from an outer layer to an inner layer, but these extra layers add to the cost of the product.

This was one of the main drivers in changing to having two connectors on different edges of the board: doing so saves having to route tracks all the way across the PCB. So we arrived at a design that incorporated a rough split of which signals were going to end up on each of the connectors. The exact order of the signals wasn’t yet defined.

Trial PCB layouts

We experimented with trial PCB layouts for the Compute Module 4 and the CM4 IO Board to see how easy it would be to route the signals; even at this stage, the final size of the CM4 hadn’t been fixed. Over time, and after juggling parts around the PCB, I came to a sensible compromise. There were lots of things to consider, including the fact that the taller components had to go on the top side of the PCB.

The pinout was constantly being adjusted to an ordering that was a good compromise for both the CM4 and the IO Board. The IO Board layout was a really important consideration: after we made the first prototype boards, we decided to change the pinout slightly to make PCB layout on the IO Board even easier for the end user.

When the prototype Compute Module 4 IO Boards arrived back from manufacture, the connectors hadn’t arrived in time to be assembled by machine, so I fitted them by hand in the lab. Pro tip: if you have to fit connectors by hand, take your time to ensure they are lined up correctly, and use lots of flux to help the solder flow into the joints. Sometimes people use very small soldering iron tips thinking it will help; in fact, one of the goals of soldering is to get heat into the joint, and if the tip is too small it will be difficult to heat the solder joint sufficiently to make a good connection.

Compute Module 4 IO Board

New features

Whilst it was easy to add some headline features like a second HDMI port, other useful features don’t grab as much attention. One example is that we have simplified the powering requirements. Previous Compute Modules required multiple PSUs to power a board, and the power-up sequence had to be exactly correct. Compute Module 4 simply requires a single +5V PSU.

In fact, the simplest possible base board for Compute Module 4 just requires a +5V supply and one of the connectors and nothing else. You would need a CM4 variant with eMMC and wireless connectivity; you can boot the module with the eMMC, wireless connectivity gives you networking, and Bluetooth connectivity gives you access to IO devices. If you do add extra IO devices the CM4 also can provide a +3.3V supply to power those devices, avoiding the need for an external power supply.

We have seen some customers experience issues with adding wireless interfaces to previous Compute Modules, so a really important requirement was to provide the option of wireless support. We wanted to be as flexible as possible, so we have added support for an external antenna. Because radio certification can be a very hard and expensive process, we have a pre-certified external antenna kit that can be supplied with Compute Module 4. This should greatly simplify product certification for end products, although engineering designers should check to make certain of meeting all local requirements.

Antenna Kit and Compute Module 4

PCIe

This is probably the most exciting new interface to come to Compute Module 4. On the existing Raspberry Pi 4, this interface is used internally to add the XHCI controller which provides the USB 3 ports. By providing the PCIe externally, we are giving end users the choice of how they would like to use this interface. Many applications don’t need USB 3 performance, so the end user can make use of it in other ways — for NVMe drives, to take one example.

Ethernet

In order to have wired Ethernet connectivity with previous Compute Modules, you needed to add an external USB-to-Ethernet interface. This adds complexity to the IO board, and one of the aims of the new Compute Module 4 is to make interfacing to it simple. With this in mind, we added a physical Ethernet interface to CM4, and we also took the opportunity to add support for IEEE1588 to this. As a result, adding Gigabit wired networking to CM4 requires only the addition of a magjack; no extra silicon is needed. Because this is a true Gigabit interface, it is also faster than the USB-to-Ethernet interfaces that previous Compute Modules use.

Raspberry Pi Compute Module 4

Open-sourcing the Compute Module 4 IO Board design files

Early on in the process, we decided that we were going to open-source the design files for the Compute Module 4 IO Board. We used our big expensive CAD system for Compute Module 4 itself, and while we could have decided to do the design for the IO Board in the big CAD system too and then port it across to KiCAD, it’s easy to introduce issues in the porting process.

So, instead, we used KiCAD for the IO Board from the start, and the design files that come out of KiCAD are the same ones that we use in manufacture. During development I had both CAD systems running at the same time on the computer.

Easier integration and enhanced possibilities

We have made some big changes to our new Compute Module 4 range, and these should make integration much simpler for our customers. Many interfaces now just need a connector and power, and the new form factor should enable people to design more compact and more powerful products. I look forward to seeing what our customers create over the next few years with Compute Module 4.

High-density connector on board underside

Get your Compute Module 4

The new Raspberry Pi Compute Module 4 is available from our network of Approved Resellers. Head over to the Compute Module 4 product page and select your preferred variant to find your nearest reseller.

Can’t find a reseller near you? No worries. Many of our Approved Resellers ship internationally, so try a few other locations.

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ClockSquared Mini

Willem has been working on a tiny word clock, the Clocksquared Mini:

Summer break is here, and with some time to spare I decided to challenge myself with a project that I call “Clocksquared Mini”. It is Clocksquared, but in a tiny wristwatch package. This gives rise to a major challenge, as everything has to be shrunk down approximately ten times from a 300x300x50 mm to an approximately 35x35x7 mm package. Moreover, running everything off a tiny battery whilst maintaining an acceptable battery life also turns out to be quite difficult.

Project info at willemm.nl.

from Dangerous Prototypes https://ift.tt/2TdBvBq

Vulkan update: merged to Mesa

Today we have another guest post from Igalia’s Iago Toral, who has spent the past year working on the Mesa graphic driver stack for Raspberry Pi 4.

Four months ago we announced that work on the Vulkan effort for Raspberry Pi 4 (v3dv) was progressing well, and that we were moving the development to an open repository.

vkQuake3 on Raspberry Pi 4

This week, the Vulkan driver for Raspberry Pi 4 has been merged with Mesa upstream, becoming one of the official Vulkan Mesa drivers. This brings several advantages:

  • Easier to find: now anyone willing to test the driver just needs to go to the official Mesa repository
  • Bug tracking: issues/bugs can now be filed on the official Mesa repository bug tracker. If the problem affects other parts of the project, it will be easier for us to involve other Mesa developers.
  • Releasing: v3dv will be included in all Mesa releases. In due course, you will no longer need to go to an external repository to obtain the driver, as it will be included in the Mesa package for your distribution.
  • Maintenance: v3dv will be included in the Mesa Continuous Integration system, so every merge request will be tested to ensure that our driver still builds. More effort can go to new features and bug fixes rather than just keeping up with upstream changes.

Progress, and current status

We said back in June that we were passing over 70,000 tests from the Khronos Conformance Test Suite for Vulkan 1.0, and that we had an implementation for a significant subset of the Vulkan 1.0 API. Now we are passing over 100,000 tests, and have implemented the full Vulkan 1.0 API. Only a handful of CTS tests remain to be fixed.

Sascha Willems’ deferred multisampling demo

This doesn’t mean that our work is done, of course. Although the CTS is a really complete test suite, it is not the same as a real use case. As mentioned some of our updates, we have been testing the driver with Vulkan ports of the original Quake trilogy, but deeper and more detailed testing is needed. So the next step will be to test the driver with more use cases, and fixing any bugs or performance issues that we find during the process.

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