Closing The Loop On An Artificial Pancreas

December 19, 2016 by Dan Maloney 43 Comments

Life as a parent is never easy, but when you’ve got a kid with Type 1 diabetes it’s a little harder. Sometimes it feels like a full-time job in itself; there’s never a break. With carb counts and insulin ratios that change throughout the day, every meal is a medical procedure. A romp in the snow or a long bike ride can send her blood glucose plummeting. The overnights are the worst, though, because you never know if you overestimated the number of carbs at dinner and gave her too much insulin. Low blood glucose is easily treated with a few sips of juice, but if it goes unnoticed in the middle of the night, it could be fatal. That’s why parents of diabetics are always a little glassy eyed — we rarely sleep.

Why is all this necessary? It’s because Type 1 diabetes (T1D) is an autoimmune disease that attacks the insulin-producing beta cells in the pancreas. Once those cells are dead, insulin is no longer produced, and without insulin the rest of the cells in the body can’t take in the glucose that they need to live. Diabetics have to inject just the right amount of insulin at just the right time to coincide with the blood glucose spike that occurs after meals. Knowing how much to give and when is why we say we have to “learn to think like a pancreas.”

1-1-2-4_ping — Animas Ping insulin pump, partial teardown. The cylinder on the bottom is the battery, the motor and syringe compartment are on top. Source: Animas

Things are better than they used to be, for sure. Insulin pumps have been a game changer for T1Ds. An insulin pump is just a tiny syringe pump. A small motor moves the plunger on a disposable syringe filled with a few days worth of insulin. The hormone is delivered through a small catheter placed under the skin every few days — painful, but better than a needle stick with every meal and snack. A computer keeps track of everything and provides safety against overdosing on insulin, so it’s terribly convenient, but we still need to “think like a pancreas” and calculate the amount to deliver.

Even with its shortcomings, my daughter’s pump has been a blessing, and I’ll do whatever it takes to keep her in the latest gear. Pumps generally cost about $5000 or so, and need to be replaced every three years. While I’m not looking forward to paying the bill when her current pump gives up the ghost, I am certainly keen to do a teardown on the old one. I suspect it’s dead simple in there — a tiny gear motor, some kind of limit switches, and a main board. It’ll be painful to see how little my money buys, but it’ll be cool to play around with it.

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Books You Should Read: The Hardware Hacker

December 16, 2016 by Brian Benchoff 20 Comments

There’s no one quite like Andrew ‘Bunnie’ Huang. His unofficial resume begins with an EE degree from MIT, the author of Hacking the Xbox, creator of the Chumby, developer of the Novena, the first Open Source laptop, and has mentored thousands of people with dozens of essays from his blog.

Above all, Bunnie is a bridge across worlds. He has spent the last decade plying the markets of Shenzhen, working with Chinese manufacturers, and writing about his experiences of taking an idea and turning it into a product with the help of Chinese partners. In short, there is no person better suited to tell the story of how Shenzhen works, what can be done, and how to do it.

Bunnie’s The Hardware Hacker ($29.95, No Starch Press) is the dead tree expression of years of living and working in Shenzhen, taking multiple products to market, and exploring the philosophy that turned a fishing village into a city that produces the world’s electronic baubles.

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Set Your Clocks To Decimal Time

December 14, 2016 by Steven Dufresne 168 Comments

Many stop lights at street intersections display a countdown of the remaining seconds before the light changes. If you’re like me, you count this time in your head and then check how in sync you are. But did you know that if the French had their way back in the 1890s when they tried to introduce decimal time, you’d be counting to a different beat? Did you know the Chinese have used decimal time for millennia? And did you know that you may have unknowingly used it already if you’ve programmed in Linux? Read on to see what decimal time is along with the answers to these questions.

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My Beef With Ham Radio

December 12, 2016 by Dan Maloney 373 Comments

My amateur radio journey began back in the mid-1970s. I was about 12 at the time, with an interest in electronics that baffled my parents. With little to guide me and fear for my life as I routinely explored the innards of the TVs and radios in the house, they turned to the kindly older gentleman across the street from us, Mr. Brown. He had the traditional calling card of the suburban ham — a gigantic beam antenna on a 60′ mast in the backyard – so they figured he could act as a mentor to me.

Mr. Brown taught me a lot about electronics, and very nearly got me far enough along to take the test for my Novice class license. But I lost interest, probably because I was an adolescent male and didn’t figure a ham ticket would improve my chances with the young ladies. My ham ambitions remained well below the surface as life happened over the next 40 or so years. But as my circumstances changed, the idea of working the airwaves resurfaced, and in 2015 I finally took the plunge and earned my General class license.

The next part of my ham story is all-too-familiar these days: I haven’t done a damn thing with my license. Oh, sure, I bought a couple of Baofeng and Wouxun handy-talkies and lurked on the local repeaters. I even bought a good, solid HF rig and built some antennas, but I’ve made a grand total of one QSO — a brief chat with a ham in Texas from my old home in Connecticut on the 10-meter band. That’s it.

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You Can Have My LM386s When You Pry Them From My Cold Dead Hands

December 7, 2016 by Elliot Williams 137 Comments

Everyone has a chip-of-shame: it’s the part that you know is suboptimal but you keep using it anyway because it just works well enough. Maybe it’s not what you would put into a design that you’re building more than a couple of, but for a quick and dirty lashup, it’s just the ticket. For Hackaday’s [Adam Fabio], that chip is the TIP120 transistor. Truth be told, we have more than one chip of shame, but for audio amplification purposes, it’s the LM386.

The LM386 is an old design, and requires a few supporting passive components to get its best performance, but it’s fundamentally solid. It’s not noise-free and doesn’t run on 3.3 V, but if you can fit a 9 V battery into your project and you need to push a moderate amount of sound out of a speaker, we’ll show you how to get the job done with an LM386.

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Daylight Saving Time – Whys And Why Nots

November 28, 2016 by Steven Dufresne 87 Comments

We recently went through our twice yearly period of communal venting called adjusting for daylight saving time (DST), or British Summer Time (BST) as it’s called in the UK. But why are we changing the time? Seriously, who caused all this? Does it do any good? Do we still need it? And what can we do about it? As it turns out, most of us want it, as you’ll see below.

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A Rebel Alliance For Internet Of Things Standards

November 21, 2016 by Alasdair Allan 41 Comments

Back when the original Internet, the digital one, was being brought together there was a vicious standards war. The fallout from the war fundamentally underpins how we use the Internet today, and what’s surprising is that things didn’t work out how everyone expected. The rebel alliance won, and when it comes to standards, it turns out that’s a lot more common than you might think.

Looking back the history of the Internet could have been very different. In the mid eighties the OSI standards were the obvious choice. In 1988 the Department of Commerce issued a mandate that all computers purchased by government agencies should be OSI compatible starting from the middle of 1990, and yet two years later the battle was already over, and the OSI standards had already lost.

In fact by the early nineties the dominance of TCP/IP was almost complete. In January of 1991 the British academic backbone network, called JANET (which was based around X.25 colored book protocols), established a pilot project to host IP traffic on the network. Within ten months the IP traffic had exceeded the levels of X.25 traffic, and IP support became official in November.

“Twenty five years ago a much smaller crowd was fighting about open versus proprietary, and Internet versus OSI. In the end, ‘rough consensus and running code’ decided the matter: open won and Internet won,”

—Marshall Rose, chair of several IETF Working Groups during the period

This of course wasn’t the first standards battle, history is littered with innumerable standards that have won or lost. It also wasn’t the last the Internet was to see. By the mid noughties SOAP and XML were seen as the obvious way to build out the distributed services we all, at that point, already saw coming. Yet by the end of the decade SOAP and XML were in heavy retreat. RESTful services and JSON, far more lightweight and developer friendly than their heavyweight counterparts, had won.

“JSON appeared at a time when developers felt drowned by misguided overcomplicated XML-based web services, and JSON let them just get the job done,”

“Because it came from JavaScript, and pretty much anybody could do it, JSON was free of XML’s fondness for design by committee. It also looked more familiar to programmers.”

—Simon St. Laurent, content manager at LinkedIn and O’Reilly author

Yet, depending on which standards body you want to listen to, ECMA or the IETF, JSON only became a standard in 2013, or 2014, respectively and while the IETF RFC talks about semantics and security, the ECMA standard covers only the syntax. Despite that it’s unlikely many people have actually read the standards, and this includes the developers using the standard and even those implementing the libraries those developers depend on.

We have reached the point where standardization bodies no longer create standards, they formalize them, and the way we build the Internet of Things is going to be fundamentally influenced by that new reality.

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