New Part Day : A Sensor Chip For 3D Color X-Ray Imaging

February 14, 2019 by Anool Mahidharia 19 Comments

We all know CERN as that cool place where physicists play with massive, superconducting rings to smash atoms and subatomic particles to uncover secrets of matter in the Universe. To achieve this aim, they need to do a ton of research in other areas, such as development of special particle detectors.

While such developments are essential to the core research needs of the Centre, they also lead to spinoff applications for the benefit of society at large. One such outcome has been the Medipix Collaborations – a family of read-out chips for particle imaging and detection that can count single photons, allowing X-rays and gamma rays to be converted to electrical signals. It may not be possible for us hackers to get our hands on these esoteric sensors, but these devices are pretty interesting and deserve a closer look. Medipix sensors work like a camera, detecting and counting each individual particle hitting the pixels when its electronic shutter is open. This enables high-resolution, high-contrast, noise hit free images – making it unique for imaging applications.

Some months back, CERN announced the first 3D color X-ray of a human made possible using the Medipix devices. The result is a high-resolution, 3D, color image of not just living structures like bones, muscular tissues and vessels, but metal objects too like the wrist watch, seen in the accompanying photograph. The Medipix sensors have been in development since the 1990’s and are presently in their 4th “generation”. Each chip consists of a top semiconducting sensor array, made from gallium arsenide or cadmium telluride. The charge collected by each pixel is transported to the CMOS ASIC electronics via “bump bonds”. The integration is vertical, with each sensing pixel connected via the bump bond to an analog section followed by a digital processing layer. Earlier versions were limited, by technology, in their tiling ability for creating larger matrices of multiple sensors. They could be abutted on three sides only, with the fourth being used for on-chip peripheral logic and wire-bond pads that permit electronic read-out. The latest Medipix4 Collaboration, still under some development, eliminates this short coming. Through-silicon-via (TSV) technology provides the possibility of reading the chips through copper-filled holes that bring the signals from the front side of the chip to its rear. All communication with the pixel matrix flows through the rear of the chip – the peripheral logic and control elements are integrated inside the pixel matrix.

The Analog front end consists of a pre-amplifier followed by a window discriminator which has upper and lower threshold levels. The discriminator has four bits for threshold adjustment as well as polarity sensing. This allows the capture window to be precisely set. The rest of the digital electronics – multiplexers, shift registers, shutter and logic control – helps extract the data.

Further development of the Medipix (Tech Brief, PDF) devices led to a separate version called Timepix (Tech Brief, PDF). These new devices, besides being able to count photons, are capable of two additional modes. The first mode records “Time-Over-Threshold”, providing rough analog information about the energy of the photon. It does this by counting clock pulses for the duration when the signal stays above the discrimination levels. The other mode, “Time of Arrival”, measures arrival time of the first particle to impinge on the pixel. The counters record time between a trigger and detection of radiation quanta with energy above the discrimination level, allowing time-of-flight applications in imaging.

Besides medical imaging, the devices have applications in space, material analysis, education and of course, high energy physics. Hopefully, in a few years, hackers will lay their hands on these interesting devices and we can get to know them better. At the moment, the Medipix website has some more details and data sheets if you would like to dig deeper. For an overview on the development of such single photon detectors, check out this presentation from CERN – “Single X-Ray Photon Counting Systems: Existing Systems, Systems Under Development And Future Trends” (PDF).

Hack My House: Garage Door Cryptography Meets Raspberry Pi

February 13, 2019 by Jonathan Bennett 57 Comments

Today’s story is one of victory and defeat, of mystery and adventure… It’s time to automate the garage door. Connecting the garage door to the internet was a must on my list of smart home features. Our opener has internet connection capabilities built-in. As you might guess, I’m very skeptical of connecting a device to the internet when I have no control over the software running on it.

The garage door is controlled by a button hung on the garage wall. There is only a pair of wires, so a simple relay should be all that is needed to simulate the button press from a Raspberry Pi. I wired a relay module to a GPIO on the Pi mounted in the garage ceiling, and wrote a quick and dirty test program in Python. Sure enough, the little relay was clicking happily– but the garage door wasn’t budging. Time to troubleshoot. Does the push button still work? *raises the garage door* yep. How about the relay now? *click…click* nope.

You may have figured out by now, but this garage door opener isn’t just a simple momentary contact push button. Yes, that’s a microcontroller, in a garage door button. This sort of scenario calls for forensic equipment more capable than a simple multimeter, and so I turned to Amazon for a USB oscilloscope that could do some limited signal analysis. A device with Linux support was a must, and Pico Technology fit the bill nicely.

Searching for a Secret We Don’t Actually Need

My 2 channel Picotech oscilloscope, the 2204A, finally arrived, and it was time to see what sort of alien technology was in this garage door opener. There are two leads to the button, a ground and a five volt line. When the button is pressed, the microcontroller sends data back over that line by pulling the 5 V line to ground. If this isn’t an implementation of Dallas 1-wire, it’s a very similar concept.

Continue reading “Hack My House: Garage Door Cryptography Meets Raspberry Pi” →

EF50: The Tube That Changed Everything

February 12, 2019 by Al Williams 32 Comments

From today’s perspective, vacuum tubes are pretty low tech. But for a while they were the pinnacle of high tech, and heavy research followed the promise shown by early vacuum tubes in transmission and computing. Indeed, as time progressed, tubes became very sophisticated and difficult to manufacture. After all, they were as ubiquitous as ICs are today, so it is hardly surprising that they got a lot of R&D.

Prior to 1938, for example, tubes were built as if they were light bulbs. As the demands on them grew more sophisticated, the traditional light bulb design wasn’t sufficient. For one, the wire leads’ parasitic inductance and capacitance would limit the use of the tube in high-frequency applications. Even the time it took electrons to get from one part of the tube to another was a bottleneck.

There were several attempts to speed tubes up, including RCA’s acorn tubes, lighthouse tubes, and Telefunken’s Stahlröhre designs. These generally tried to keep leads short and tubes small. The Philips company started attacking the problem in 1934 because they were anticipating demand for television receivers that would operate at higher frequencies.

Dr. Hans Jonker was the primary developer of the proposed solution and published his design in an internal technical note describing an all-glass tube that was easier to manufacture than other solutions. Now all they needed was an actual application. While they initially thought the killer app would be television, the E50 would end up helping the Allies win the war.

Continue reading “EF50: The Tube That Changed Everything” →

Chris Gammell Talks Circuit Toolboxes

February 11, 2019 by Dan Maloney 9 Comments

Chris Gammell wants to know: What’s in your circuit toolbox?

Personally, mine is somewhat understocked. I do know that in one of my journals, probably from back in the 1980s, I scribbled down a schematic of a voltage multiplier I had just built, with the classic diode and capacitor ladder topology. I probably fed it from a small bell transformer, and I might have gotten a hundred volts or so out of it. I was so proud at the time that I wrote it down for posterity with the note, “I made this today!”

I think the whole point of Chris’ 2018 Hackaday Superconference talk is precisely what I was trying to get at when I made my “discovery” — we all have circuits that just work for us, and the more you have, the better. Most readers will recognize Chris from such venues as The Amp Hour, a weekly podcast he hosts with Dave Jones, and his KiCad tutorial videos. Chris has been in electrical engineering for nearly twenty years now, and he’s picked up a collection of go-to circuits that keep showing up in his designs and making life easier, which he graciously shared with the crowd.

As Chris points out, it’s the little circuits that can make the difference. Slide after slide of his talk had schematics with no more than a handful of components in them, covering applications from dead-simple LED power indicators and switch debouncing to IO expansion using a 74HC595. And as any sensible engineer might, Chris’ toolbox includes a good selection of power protection circuits, everything from polarity reversal protection with a MOSFET and a zener to a neat little high-side driver shutoff using a differential amp and an optoisolator.

My favorite part of the talk was the “Codeless” section — things you can do with discrete components that make microcontroller circuits better. We see the “You could have used a 555!” comments from readers all the time, and Chris agrees, at least to a point. He aptly notes that microcontrollers can wake up with their IO pins in unknown states, and offered several circuits to keep the potential for mischief at bay, such as Schmitt trigger power-on reset or the simple addition of a pull-down resistor to default a MOSFET to a safe state. There’s a lot that code can accomplish, but adding just a few parts can make a circuit much safer and useful.

Chris acknowledges that in any audience, everyone is always at different places with regard to their hardware learning curve, so what’s old hat to someone might be a fresh revelation to another. Still, everything is new to someone at some point, and that’s often the best time to write it down. That’s what I did all those years ago with that voltage multiplier, and it never left me as a result. It’s good advice, and if you haven’t started building your own circuit toolbox, now’s the time.

Continue reading “Chris Gammell Talks Circuit Toolboxes” →

Review: IchigoJam Single Board Computer

February 11, 2019 by Jenny List 60 Comments

It won’t replace your beloved Rasbperry Pi, but it’s worth saying hello to this “Strawberry Jam”, straight out of Japan. It’s an equally delicious way to get people interested in the basics of coding.

My hackerspace friend Jim is a lucky bloke, for last year he was able to take an extended holiday through a succession of East Asian countries. We were treated to online pictures of beautiful scenery and beaches, city lights, and of course exciting tech destinations such as hardware markets and hackerspaces. On his return he tossed a package on the table in front of me and said “Jenny, you might like to take a look at that, these are big in Japan!” Inside was an electronic kit and a few pieces of documentation, with Japanese text.

A Different Way To Get Kids Coding

What he’d given me was an IchigoJam (Best translation I’ve been given is “Strawberry Jam”), a small single-board computer aimed at young people. In the style of the 8-bit machines of the 1980s, it runs a comprehensive BASIC interpreter and plugs into a TV set, though it brings itself up-to-date with a USB-A socket for a keyboard. At its heart is an NXP LPC1114F102 ARM Cortex-M0 microcontroller with 32KB of Flash and 4KB of SRAM, and though the board Jim passed to me has a surface-mount example it’s clear that it was also designed for the now-obsolete DIP variant of the chip. If you were to think of this as an odd hybrid of a BASIC Stamp, a Raspberry Pi, and one of the smaller MBED boards, you probably wouldn’t be too far from the mark. What follows is my impression of it based on the information at hand. Sadly the IchigoJam website and forum seems only available to Japanese viewers and returns an error code from my European perspective.

Continue reading “Review: IchigoJam Single Board Computer” →

Open-Source Biology And Biohacking Hack Chat

February 11, 2019 by Dan Maloney 16 Comments

Join us on Wednesday at noon Pacific time for the open-source biology and biohacking Hack Chat!

Justin Atkin‘s name might not ring a bell, but you’ve probably seen his popular YouTube channel The Thought Emporium, devoted to regular doses of open source science. Justin’s interests span a wide range, literally from the heavens above to the microscopic world.

His current interest is to genetically modify yeast to produce spider silk, and to perhaps even use the yeast for brewing beer. He and the Thought Emporium team have been busy building out a complete DIY biology lab to support the effort, and have been conducting a variety of test experiments along the way.

Please join us for this Hack Chat, in which we’ll cover:

The how’s and why’s of yeast genetic engineering;
What it takes to set up an effective biology lab from scratch;
An update on the current status of the spider-silk yeast project; and
Where the open-source biology field is, and where it’s going.

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Open-Source Biology and Biohacking Hack Chat event page and we’ll put that in the queue for the Hack Chat discussion.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 13, at noon, Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Automate The Freight: Amazon Tackles The Last Mile Problem On Wheels

February 11, 2019 by Dan Maloney 85 Comments

We’ve been occasionally exploring examples of what could be the killer application for self-driving vehicles: autonomous freight deliveries, both long-haul and local, as well as some special use cases. Some, like UAV delivery of blood and medical supplies in Kenya, have taken off and are becoming both profitable and potentially life-saving. Others, like driverless long-haul trucking, made an initial splash but appear to have gone quiet since then. This is to be expected, as the marketplace picks winners and losers in a neverending quest to maximize return on investment. But the whole field seems to have gotten a bit sleepy lately, with no big news of note for quite a while.

That changed last week with Amazon’s announcement of Scout, their autonomous delivery vehicle. Announced first on Amazon’s blog and later picked up by the popular and tech press who repeated the Amazon material almost verbatim, Scout appears at first glance to be a serious attempt by Amazon to own the “last mile” of delivery – the local routes that are currently plied by the likes of UPS, FedEx, and various postal services. Or is it?

Continue reading “Automate The Freight: Amazon Tackles The Last Mile Problem On Wheels” →