usb 1 Comment on USB Inrush Testing

Tag: ChipWhisperer-Lite.
USB Inrush Testing.

The USB spec has limits on the ‘inrush current’

which is designed to prevent you from having 2000uF of capacitance that must be suddenly charged when your board is plugged into the USB port.
The limit works out to around 10uF of capacitance.
Your board might have much much more – so you’ll have to switch portions of your board on later with FETs as a soft-start.
For the ChipWhisperer-Lite, I naturally switch the FPGA + analog circuitry as to meet the 2.5 mA suspend current.

Thus I only have to ensure the 3.3V supply for the SAM3U2C meets the inrush limits

which is a fairly easy task.
This blog post describes how I did this testing.
The official USB Test Specs for inrush current testing describe the use of the Tektronix TCP202 which is $2000, and I don’t think I’d use again a lot.
Thus I’m describing my cheaper/easier method.

I used a differential probe (part of the ChipWhisperer project

so you can see schematics) to measure the current across a 0.22 ohm shunt resistor.
The value was selected as I happened to have one around… you might want a smaller value (0.1 ohm say) even, as the voltage drop across this will reduce the voltage to your device.
The differential probe has enough gain to give your scope a fairly clean signal.
This shows my test board, where the differential probe is plugged into a simple 2-pin header: From the bottom, you can see where I cut the USB shield to bring the +5V line through the shunt: To calibrate the shunt + gain from the diff-probe, I just used some test loads, where I measure the current flowing through them with a DMM.
You can then figure out the equation for converting the scope measurement to a current in amps.
Finally, we plug in our actual board.

Here I’ve plugged in the ChipWhisperer-Lite prototype

The following figure shows the measurement after I’ve used a math channel in PicoScope to convert the voltage to a current measurement, and I’ve annotated where some of these spikes come from: Saving the data, .

We can run through the USB Electrical Analysis Tool 2.0 to get a test result

The USB-IF tool assumes your scope saves the files with time in seconds and current in amps.

The PicoScope .csv files have time in miliseconds

so you need to import the file into Excel, divide the column by 1000, and save the file again.

Finally you should get something like this: Note the inrush charge is > 50mC

but there is an automatic waiver for anything < 150 mC. While the system would be OK due to the waiver, I would prefer to avoid exceeding the 50 mC limit. In this case there’s an easy solution – I can delay the USB enumeration slightly from processor power-on, which limits the inrush to only the charging of the capacitors (which is done by ~15mS). This results in about 47 mC. This means I’ve got about 100 mC of headroom before I exceed the official limits. This extra headroom is needed in case of differences due to my use of the shunt for example. In addition, I should be adjusting the soft-start FET gate resistor to reduce the size of that huge soft-start spike. Ideally the capacitor charging shouldn’t draw more than the 500mA I claim when I enumerate, so that’s a little out of spec as-is. If I don’t want to change hardware I could consider using PWM on the FET gate even… March 2, 2015March 3, 2015 ChipWhisperer-Lite, tutorial, usb 1 Comment on USB Inrush Testing.

I was President of the Drexel Smart House

I’m an tech-savvy, entrepreneurially-spirited guy.
Currently, I’m a Site Reliability Engineer at Confluent, building out the hosted Confluent Cloud and helping put a streaming platform at the heart of Fortune 500 enterprises.
This is my personal blog.
Giving true meaning to the origin of the term, my blog is a catalog of my thoughts on various matters, ranging from technology tutorials to social commentary.
My goal is to create insightful, relevant content that you can put to work in your personal and professional life.
Some of this will be tutorials aimed at helping others solve problems I’ve had myself, while others will serve to build meaningful discussion around oft-neglected topics.
If you are in the early stages of your technical career and aspire to change the world, then this blog is for you.
I typically post once a month.
To make sure you don’t miss my newest posts, .

You can subscribe via RSS or email

I do not accept advertising, but do occasionally take on consulting and contract work.
Contact me if you’re interested in hiring me.
My Top Posts.
If you are new to my site, you might want to start with my most popular posts.

Custom JMeter Samplers and Config Elements

Automatic Model Validation using Jersey

Jackson, and Hibernate Validator.

Java SSL with Multiple Keystores

Finding Generic Type Parameters with Guava

Dropbox Referrals using Mechanical Turk

On Lifetimes Within a Lifetime.
You can also check my blog’s archive for a list of every post I have written or use the search function in the sidebar to find other posts that might be of interest.
My professional career has been spent as a Software Engineer/DevOps/SRE while dabbling in entrepreneurial and investment pursuits (both inside and outside my day jobs).

I graduated from the accelerated BS/MS program at Drexel University

Both my undergraduate and graduate degrees are in electrical engineering.
My undergraduate concentration was in telecommunications and digital signal processing, and my graduate specialization was in controls, robotics, and intelligent systems.
Previously, I was President of the Drexel Smart House, a student-led technology incubator with a focus on smarter living. I spent two years in the Applied Communications and Information Networking center, a defense contractor focused on network-aware intelligent applications. You can learn more about my education and experience on my LinkedIn resume.

While leading the Drexel Smart House

I developed special interests in the areas of corporate innovation, sustainability, and education. My professional goal is to serve mankind’s critical needs through the fusion of business, design and technology.

My blog is built on WordPress 3.2 (self-hosted)

My theme is a (very) slightly customized version of BuyNowShop‘s “Desk Mess Mirrored.” Crowd Favorite’s Carrington Blog.
I did all customization myself.
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though the Metal API is much lower level

Search Previous Next → Learning the Metal API.
January 4.

2019 So I’m in the process of learning the Metal API

which is Apple’s replacement for OpenGL ES.
The principles are fairly similar, though the Metal API is much lower level.

There are several web sites devoted to Metal

but my eventual goal is to implement image-based CSG (Constructive Solid Geometry) in Metal for an update to the Kythera application.
And that requires a deeper understanding of Metal than most introductions which seem to stop at drawing an object on the screen and perhaps adding a texture map to the object.
The best way to learn something is to try to explain it–so I’ve started writing a document showing how to build a Macintosh-based Metal API application in Objective C, and going from a blank screen to a deferred shading example.
In this case, the deferred shading example results in a rotating teapot with fairy lights and indirect illumination rendering at 60 frames/second: The sample code is uploaded at GitHub, with the different examples in their own branches.
And the first draft of the Metal Introduction Document (as a PDF with links to relevant documents) can be downloaded from here.
Feedback is appreciated.
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because it is an excellent Zelda-style dungeon crawler

Ben’s Favorite Games of 2016.
Like in 2014 and 2015, I’ve made another list of favorites.
I hope you’ll find something cool that you would have otherwise missed.
This choice is super obvious and there’s probably very little I could write about here that hasn’t already been said.
I love the lighthearted feel of the game and I love ridiculous fan art community that has sprung up around it. The incredible number of good design decisions hidden throughout the game are overwhelming at times.
I can’t wait to finish this list so I can go back and play it more.
If the Oculus had been more widespread I’m absolutely certain this game would have been on many end-of-year lists.
Sadly, I’m willing to be that they did not make their budget back on this.
This is too bad, because it is an excellent Zelda-style dungeon crawler.
VR makes the whole production feel alive and epic in a way that other games can’t replicate. The art and animation are stellar.
The levels require spatial awareness and careful observation from the player.

Just like classic Zelda dungeons

before the series got too hand-holdy.
And with the game’s stationary camera.

It’s one of the few VR games that won’t give you motion sickness

so you can actually play it for more than 20 minutes at a time.
Final Fantasy XV.

I loved the Final Fantasy series when I was a teenager

but lost interest after X.

I never believed I could get into a JRPG ever again

but sure enough, it’s happening.
XV weaves strong themes of friendship, camaraderie, and road trips directly into the game mechanics in a way that’s bold and honestly unprecedented.
Every part of the game, down to the most minor detail, was built with great care and craftsmanship.
I actually care about the characters and don’t mind the often clunky dialog one bit.

Final Fantasy is relevant again

You didn’t think I could get through this list without a roguelike, did you.
You pilot drones through derelict spaceships, searching for resources, hoping the whole time that your careful preparations and meticulous planning will let you slip by unnoticed by the horrible things occupying each ship.
One of the best examples of incredible atmosphere and verisimilitude, all in a super low-budget game.
A great, creepy, tense experience.
Dying Light: The Following.
This DLC for my favorite game last year is so huge that it might as well be a whole new game.
The drastic change in setting and new mechanics really do make the game feel fresh.
The car is actually fun to drive, .

And speeding away from Volatiles at night is uniquely terrifying

Forcing the player to go out at night to sneak into a Volatile nest is a brilliant design choice.
Steppy Pants.
A wonderfully designed frantic co-op experience.
We need more games like this.
Even your non-game-playing friends will enjoy this, I promise.
Get it and four controllers for your next get-together.
It will go over well.
Another game that I can’t really say much about that hasn’t already been said.

A fantastic return to form for the now largely unrecognizable id Software

Large, sprawling levels are a high point.
Probably my favorite soundtrack of the year.
Just get it.
No Man’s Sky.
If this was released quietly, without Sony’s relentless hype, it would’ve been remembered as 2016’s most underrated game.
Playing it feels like being inside a concept album: a relentlessly curated, laser focused experience, surreal and dreamy.
The art and music are the game’s greatest assets.
Pony Island.
I really don’t want to say anything about this game.
It’s better if you don’t know anything about it when you go in.
It’s ridiculously cheap.
Just get it and play it with some friends.
Games I played this year that came out in previous years.
Wow is this game wonderful.

Feels like a proper follow-up to Dark Souls

Mechanics tuned to perfection.
Accidentally stumbling into huge new areas is still an amazing experience.
Metal Gear Solid 2.
I’m only 15 years late.
It still holds up pretty well.
Games of 2016 that I didn’t really get around to but look cool.
The Flame in the Flood.

A roguelike about traveling the American south

By former BioShock devs.
I’m sold.
Dishonored 2.
I’ve only played the first few missions, but I already love the game. Totally absorbing, with many opportunities for creative problem solving, which is my favorite kind of gameplay.
Titanfall 2.

The original Titanfall was my favorite game of 2014

but I’ve been so into Overwatch this year that I just didn’t have room for another multiplayer shooter.
These are the kind of problems you want.
Some random financial advice Horizon’s amazing photo mode Follow.
Ben’s Favorite Games of 2016.
Post to.

OwlboyStoriesStories: The Path of Destinies

Primary Menu Tag Archives: Warframe.
On Honorable Mentions, 2016.
February 5.

2017 Leave a comment As is becoming tradition

for the end of January we recorded a two-part “Games of the Year” show, in which we talk about the things we enjoyed playing in 2016.
Both parts are now out, but here are some things that I thought were amazing, but didn’t make the cut.
Stumbling into this game was a bit of a fluke.

The game chosen for Game of the Month in January was pretty boring

and there was a lot of desire for co-op, so a few of us gave this another try.
It turns out that space ninjas are actually pretty cool.
There are a variety of characters with different abilities.

Gun variety that gives Borderlands a run for its money

and a movement system and level design that emphasizes how acrobatic the playable characters can be.
Unexpectedly, there’s also an actual plot.
I did mention this one on the podcast a few weeks ago, but it’s worth repeating.
Owlboy is one of several games with a very long development history to release in 2016, and the only one so far that I’ve finished.
(For the record, it was announced between Final Fantasy Versus XIII and The Last Guardian and released slightly before both.) It’s a platformer that superficially resembles a metroidvania, but is much more linear than most examples of that genre.
There’s also not a lot of actual platforming, as the main character has unlimited flight.
This game looks amazing art-wise; the music is also excellent.
There’s a lot of humor in some of the dialogue, but other parts are much more serious.
I didn’t mention this because I thought it might become a game of the month, but that seems unlikely at this point.
Stories: The Path of Destinies.
This probably isn’t going to make any “Best of” lists for 2016, but I still think it’s worth a mention.
Stories is a mostly isometric action-RPG of sorts, .

That looks like diablo but plays kind of like the Arkham games when fighting things

There’s a heavy emphasis on positioning, counterattacks, and keeping your combo string going which makes it pretty fun.
The main draw of this game is that it plays like a choose-your-own-adventure book.
A complete playthrough from the start to an ending is probably between 60-90 minutes, and is shaped by the decisions you make (usually at the start of each chapter).
When you start.

These are all going to be Bad Ends in some way or another

but each to you get to one, you can learn a “Truth” that can help guide you toward endings that you haven’t seen yet.
Once you have all 4, you can get to the real ending (you can’t stumble into it before that).
It’s not the first time I’ve seen this concept, but it is one of the best executions I’ve played.
OwlboyStoriesStories: The Path of Destinies.

developed by the UCL enterprise MAGiCAL Projects

Andrew Burn”s personal website.
Missionmaker is a game-authoring software tool for making 3D videogames quickly with no specialist programming knowledge.

The current version was developed in a collaboration with the British Library

to enable users to make games based on Shakespeare’s Macbeth.
It’s the latest in a series of projects I’ve led in this area, developed by the UCL enterprise MAGiCAL Projects, which I direct.
This project grew out of an earlier version, built in Unity during a research project funded by the Arts and Humanities Reseach Council to develop a new game- authoring tool for the Anglo-Saxon epic Beowulf.
This collaboration between English.

Media and Drama at the IOE with UCL Anglo-Saxon scholars

the British Library, the University of Sydney and Game City, Nottingham, explored how making game adaptations of literary texts can help students at all levels to understand and engage with literature in new ways.
THE NEW MACBETH MISSIONMAKER This was developed with colleagues Jane Coles and Theo Bryer at UCL IOE, and Stella Wisdom, .

Digital curator at the British Library

Also with colleagues in schools in London and Yorkshire, and PGCE English students at UCL.
The teachers’ Introduction was written by James Durran, English Adviser for North Yorkshire.

The software was launched at the British Library on April 21

It was launched on Steam as a free early access software in May 2019, where it can be downloaded and reviewed.
A national competition was held by MAGiCAL for the best Macbeth video games made by schools, from February to May 2019.
The games will be judged by a panel including leading figures from the RSC, the British Library, the Shakespeare Institute, and Cambridge University Press.
The software was developed by Abel Drew and Bruno de Paula for DDZ games, and funded by a UCL Higher Education Innovation Fund grant.
Here’s a video of demo game made with the software, showing the final conflict between Macbeth and Macduff from the point of view of one of the witches.

And here’s a video showing the process of making a Macbeth game

THE BEOWULF MISSIONMAKER The new tool was developed during the project.
It was used by groups in schools, workshops at Game City, Nottingham, drama students in Sydney, and UCL Anglo-Saxon students to make a variety of games.
Here’s a videocapture of a sample game using the current version of the software, about to be released for sale (Winter 2017).
And here’s a video capture of one made by two UCL students, in which the player takes the role of Grendel.
It’s using an earlier prototype of the software.
The new tool is undergoing the final stages of development.
Please contact me for further information, free trials, pricing, and research proposals.  Missionmaker is owned and developed by MAGiCAL Projects at UCL Institute of Education.
THE HISTORY Missionmaker was developed originally in a project directed by David Buckingham and myself, with project researcher Caroline Pelletier and Immersive Education Ltd, a software company in Oxford.
The project was funded by the PACCIT-Link programme: the programme evaluation, including a section on the Making Games project, can be found here.
The tool was designed to develop aspects of media education conceived of as forms of literacy: an understanding of game design through playing games, but also making them.
This shift to an emphasis on the production of media texts was already growing in media education, but while it was easy enough to see how making films, radio programmes, newspapers and websites might work in the classroom, making games was more challenging, and had previously either depended on a grasp of programming, or on the use of game-making entertainment packages which offered little insight into how conditionality and procedural narratives were designed.
SHAKESPEARE GAMES During and after the project, I found many occasions to work on game-design projects, especially with my colleague James Durran, formerly an Advanced Skills Teacher at Parkside Community College in Cambridge, now English Adviser for North Yorkshire.
These projects included game design with a class, making a game based on Shakespeare’s The Tempest, and Playing Shakespeare, a collaborative project with Shakespeare’s Globe to develop a version of Missionmaker for young people to make games of Macbeth.  The Arts and Humanities Research council funded this project under its Digital Transformations programme: their case study of it can be found here.
The image below is a screengrab from a game level designed by two 13-year-old boys.

Called The Sewers of Lady Macbeth’s mind

in which the subterranean game-spaces become a psychological metaphor for the character.
And here is a video capture of the game level containing the murder of Duncan, made by two 12-year-old girls: IMPACT AND LEGACY The impact of the project and its legacy has been unusually extensive for an academic research project.

Missionmaker was developed to commercial production by Immersive

and sold well in the UK, and was subsequently used in many classrooms, colleges and other learning sites.
It has also been used in Australia, New Zealand, and several European countries.
I have given keynote addresses about it in many countries also, developing the idea of game-literacy, and of game-authoring as a subset of the media arts in education.
Articles and book chapters arising from this work can be found on the Games page on this site.
My own faculty, the UCL Institute of Education, used the project as an impact case study, submitted to the 2014 Research Evaluation Exercise.
An early version of the case study.

Which documents the extensive afterlife of Missionmaker

can be found here.

The new Beowulf tool and Macbeth tool will add another chapter to this legacy

It is being considered for a second impact case study for the next REF.
MAGICAL PROJECTS Towards the end of 2012, Immersive Education, who had been valued partners in these projects, fell victim to the recession, and the Institute of Education acquired their four educational software products, including Missionmaker.

These are now being developed and traded under the name of MAGiCAL Projects (Model

Animate, Game, Create, Learn).
We are working to develop in particular new versions of Missionmaker on the popular Unity engine.
The first of these, recently trialled in schools, is ‘Missionmaker Core’, a version with extended programming functions, .

Developed by MAGiCAL team Abel Drew and Bruno de Paula

This enables educators to teach fundamental principles of computing and programming, including Boolean logic, through satisfying 3-D game design.
Our vision here is a marriage of computer science and the media arts – exactly the union at the heart of good game design studios, and a challenge to the persistent, damaging division between the Arts and Sciences noted in the last century by CP Snow.
The interface for the alpha prototype new tool can be seen below, showing the use of different Boolean operators in constructing a game rule: Anyone who would like to discuss collaboration over Missionmaker and games-authoring is welcome to contact me for further discussion.
EXAMPLES OF GAME-MAKING TUTORIALS USING THE ‘OLD’ MISSIONMAKER Here’s one made by Classroom Multimedia, showing how to create a character and make it speak.
And here’s a very amusing one showing how to create trigger volumes – delivered by a talking cat.
It was made by CMe Creative Media Studio, the student media production team at SKH Lam Woo Memorial secondary school in Hong Kong.
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I’ve worked on a number of games which you will find in the games menu above.
At present, I’m mostly maintaining PZL, casually developing with Ogre Game Kit and trying various game engines.
Games I’ve worked on:.
Cassini Division   Space combat.
Global Warfare   Half-Life modification.
My First Planet  ???.
PZL  iOS puzzle game.
Speed Games  Several small games in various states.
Treebles  iOS platformer/puzzler.
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