Hacking Diabetes Meters, Towards An Artificial Pancreas

We’ve covered a number of diabetes-related hacks in the past, but this project sets its goals especially high. [Tim] has diabetes and needs to monitor his blood glucose levels and administer insulin accordingly. As a first step, he and a community of other diabetics have been working on Android apps to log the data when combined with a self-made Bluetooth re-transmitter.

But [Tim] is taking his project farther than previous projects we’ve seen and aiming at eventually driving an insulin pump directly from the app. (Although he’s not there yet, and user input is still required.) To that end, he’s looking into the protocols that control the dosage pumps.

We just read about [Tim] in this article in the Guardian which covers the diabetic-hacker movement from a medical perspective — the author currently runs a healthcare innovation institute and is a former British health minister, so he’s not a noob. One passage made us pause a little bit. [Tim] speaks the usual praises of tech democratization through open source and laments “If you try to commercialize [your products], you run up against all sorts of regulatory barriers.” To which the author responds, “This should ring alarm bells. Regulatory barriers are there for a reason.”

We love health hacking, and we’re sure that if we had a medical condition that could be helped by constant monitoring, that we’d absolutely want at least local smart-phone logging of the relevant data. But how far is too far? We just ran an article on the Therac-25 case study in which subtle software race conditions ended up directly killing people. We’d maybe hesitate a bit before we automated the insulin pump, but perhaps we’re just chicken.

The solution suggested by [Lord Ara Darzi] in the Guardian piece is to form collaborations between patients motivated by the DIY spirit, and the engineers (software and hardware) who would bring their expertise, and presumably a modicum of additional safety margin, to the table. We like that a lot. Why don’t we see more of that?

Embed With Elliot: Going ‘Round With Circular Buffers

Why Buffer? Because buffers cut you some slack.

Inevitably, in our recent series on microcontroller interrupts, the question of how to deal with actual serial data came up. In those examples, we were passing one byte at a time between the interrupt service routine (ISR) and the main body of code. That works great as long as the main routine can handle the incoming data in time but, as many people noted in the comments, if the main routine takes too long the single byte can get overwritten by a new one.

The solution? Make some storage room for multiple bytes so that they can stack up until you have time to process them. And if you couple this storage space with some simple rules for reading and writing, you’ve got yourself a buffer.

So read on to see how to implement a simple, straightforward circular buffer in C for microcontrollers (or heck, for anything). Buffers are such a handy tool to have in your programming toolkit that you owe it to yourself to get familiar with them if you’re not already.

Continue reading “Embed With Elliot: Going ‘Round With Circular Buffers” →

3D Printed Helix Displays Graphics In 3D

It looks like [Michel David] and his team at volumetrics.co have really upped their game: the game being production of a 3D volumetric video display.

We’ve covered an earlier version of the same technique, and still the best technical explanation of what they’re up to is to be found at their old website. But it’s a simple enough idea, and we expect that all of the difficulty is in making the details work out. But if you look at their latest video (just below the jump), we think that you’ll agree that they’ve ironed out most of the wrinkles.

Continue reading “3D Printed Helix Displays Graphics In 3D” →

Flashed The Wrong Firmware? Swap Out The LCD To Match!

We always joke about the hardware guys saying that they’ll fix it in firmware, and vice-versa, but this is ridiculous. When [Igor] tried to update his oscilloscope and flashed the wrong firmware version in by mistake, he didn’t fix it in firmware. Instead, he upgraded the LCD display to match the firmware.

See, Siglent doesn’t make [Igor]’s DSO any more; they stopped using the 4:3 aspect ratio screens and replaced them with wider versions. Of course, this is an improvement for anyone buying a new scope, but not if you’ve got the small screen in yours and can’t see anything anymore. After playing around with flashing other company’s firmware (for a similar scope) and failing to get it done over the JTAG, he gave up on the firmware and started looking for a hardware solution.

It turns out that a few SMT resistors set the output screen resolution. After desoldering the appropriate resistors, [Igor] bought a new 7″ LCD screen online only to find out that it has a high-voltage backlight and that he’d need to build an inverter (and hide the noisy circuit inside his oscilloscope). Not daunted, he went digging through his junk box until he found a backlight panel of the right size from another display.

Yet more small soldering, and he had frankensteined a new backlight into place. Of course, the larger LCD won’t fit the case without some cutting, double-sided tape, and a healthy dose of black tape all around insulates the loose electricals. Et voilá!

We have to hand it to [Igor], he’s got moxie. It’s an ugly hack, but it’s a definite screen upgrade, and a lesser hacker would have stopped after flashing the wrong firmware and thrown the thing in the trash. We’d be proud to have that scope sitting on our desk; it’s a definite conversation starter, and a badge of courage to boot.

AROS: Run An Amiga OS Like It’s 1993

We read this article on oddball open-source operating systems by [Bryan Lunduke] of the “Linux Action Show” podcast, and it caused us to play around in an Amiga-like operating system (running as a VM) for an hour. We’re pretty sure that you’ll succumb to the same fate. But even worse, the article is just the first in a series. There goes your weekend hacking productivity for the foreseeable future.

AmigaOS_3_and_clonesAROS is an open-source, API-compatible rewrite of the Amiga OS. Now, AROS is no fancy-schmancy AmigaOS4. No sir, the AROS project started in 1995 and settled on Amiga OS API version 3.1, and it stays true to its roots.

But this doesn’t mean that you’re going to have to give up the creature comforts of life in the 21st century. Get yourself a full-fledged AROS distribution, like icaros desktop, and you’ll find a pretty beefy ecosystem of applications included. It’s mostly what you’d want out of an Amiga — games, audio, video, and graphics editing software, a WebKit-based browser, and even a super-minimal word processor.

It’s retro, it’s sexy, and it’s fun. Just the ticket for running on that unused craptop gathering dust in the corner. (It’s also reported to run on Raspberry Pi running Linux.) Still not convinced? Lemmings.

TEMPEST: A Tin Foil Hat For Your Electronics And Their Secrets

Electronics leak waves and if you know what you’re doing you can steal people’s data using this phenomenon. How thick is your tinfoil hat? And you sure it’s thick enough? Well, it turns out that there’s a (secret) government standard for all of this: TEMPEST. Yes, all-caps. No, it’s not an acronym. It’s a secret codename, and codenames are more fun WHEN SHOUTED OUT LOUD!

The TEMPEST idea in a nutshell is that electronic devices leak electromagnetic waves when they do things like switch bits from ones to zeros or move electron beams around to make images on CRT screens. If an adversary can remotely listen in to these unintentional broadcasts, they can potentially figure out what’s going on inside your computer. Read on and find out about the history of TEMPEST, modern research, and finally how you can try it out yourself at home!

Continue reading “TEMPEST: A Tin Foil Hat For Your Electronics And Their Secrets” →

Passive, But Not Innocuous

Maxim Integrated recently posted a series of application notes chronicling how there’s more going on than you’d think in even the simplest “passive” components. Nothing’s safe: capacitors, resistors, and even printed circuit boards can all behave in non-ideal ways, and that can bite you in the reflow-oven if you’re not aware of them.

You might already know that capacitors have an equivalent series resistance that limits how fast they can discharge, and an equivalent inductance that models departures from ideal behavior at higher frequencies. But did you know that ceramic capacitors can also act like voltage sources, acting piezoelectrically under physical stress?

For resistors, you’ll also have to reckon with temperature dependence as well as the same range of piezoelectric and inductance characteristics that capacitors display. Worse, resistors can display variable resistance under higher voltages, and actually produce a small amount of random noise: Johnson Noise that depends on the value of the resistance.

Finally, the third article in the series tackles the PCB, summarizing a lot of potential manufacturing defects to look out for, as well as covering the parasitic capacitance, leakage currents, and frequency dependence that the actual fiberglass layers themselves can introduce into your circuit.

If you’re having a feeling of déjà-vu, the same series of articles ran in 2013 in Electronic Design but they’re good enough that we hope you won’t mind the redundant repetition all over again. And if you’re already quibbling with exactly what they mean by “passive”, we feel your pain: they’re really talking about parasitic effects, but we’ll let that slide too. We’re in a giving mood today.

[via Dangerous Prototypes]