A large part of fighting against the SARS-CoV-2 pandemic is the practice of contact tracing, where the whereabouts of an infected person can be traced and anyone who has been in contact with that person over the past days tested for COVID-19. While smartphone apps have been a popular choice for this kind of tracing, they come with a range of limitations, which is what the TraceTogether hardware token seeks to circumvent. Now [Sean “Xobs” Cross] has taken a look at the hardware that will be inside the token once it launches.
Recently, [Sean] along with [Andrew “bunnie” Huang] and a few others were asked by GovTech Singapore to review their TraceTogether hardware token proposal. At its core it’s similar to the Simmel contact tracing solution – on which both are also working – with contacts stored locally in the device, Bluetooth communication, and a runtime of a few months or longer on the non-rechargeable batteries.
The tracing protocol used is BlueTrace, which is an open application protocol aimed at digital contact tracing. It was developed by the Singaporean government, initially for use with their TraceTogether mobile app.
This smartphone app showed a number of issues. First is that Apple does not allow for iOS apps to use Bluetooth in the background, requiring the app to be active in the foreground to be useful. Apple has its own tracing protocol, but it does not cover the requirements for building a full contact graph, as [Andrew] covers in more detail. Finally, the app in general is not useful to those who do not have a recent (compatible) smartphone, or who do not have a smartphone at all.
A lot of the challenges in developing these devices lie in making them low-power, while still having the Bluetooth transceiver active often enough to be useful, as well as having enough space to store interactions and the temporary tokens that are used in the tracing protocol. As Simmel and the TraceTogether tokens become available over the coming months, it will be interesting to see how well these predictions worked out.
A process design kit (PDK) is a by now fairly standard part of any transformation of a new chip design into silicon. A PDK describes how a design maps to a foundry’s tools, which itself are described by a DRM, or design rule manual. The FOSSi foundation now reports on a new, open PDK project launched by Google and SkyWater Technology. Although the OpenPDK project has been around for a while, it is a closed and highly proprietary system, aimed at manufacturers and foundries.
The SkyWater Open Source PDK on Github is listed as a collaboration between Google and SkyWater Technology Foundry to provide a fully open source PDK and related sources. This so that one can create manufacturable designs at the SkyWater foundry, that target the 130 nm node. Open tools here should mean a far lower cost of entry than is usually the case.
Although a quite old process node at this point (~19 years), it should nevertheless still be quite useful for a range of applications, especially those that merge digital and analog circuitry. SkyWater lists their SKY130 node technology stack as:
Support for internal 1.8V with 5.0V I/Os (operable at 2.5V)
1 level of local interconnect
5 levels of metal
High sheet rho poly resistor
Optional MiM capacitors
Includes SONOS shrunken cell
Supports 10V regulated supply
HV extended-drain NMOS and PMOS
It should be noted that use of this open source PDK is deemed experimental at this point in time, and should not be used for any commercial or otherwise sensitive applications.
Like a lot of people, [Jacques] doesn’t think a big hunk of plastic light enough to carry under your arm is a piano, even if it does have 88 keys. A piano is supposed to be a hefty piece of furniture that you have to buy people pizza to help you move. So he bought a used baby grand piano. It wasn’t in very good shape, though, so while restoring it, he also added MIDI to it. You can see the finished result in the video below.
At $100, the price was right, although it cost more to move it. Between water damage, moth attacks, and storage in a garage, the piano — an old Zimmerman — needed a lot of tender loving care. When it came to MIDI, [Jacques] found a used Disklavier — a very expensive piece of kit — but it didn’t fit the Zimmerman or another piano at hand. The solenoids and optical sensors are set up for a particular piano, so what can you do? Easy! Rebuild the bar that holds the solenoids and sensors.
The exercise ball created some constraints on the design, due to its weight and the large amount of drag it creates. To work around this, the design features a foamcore and carbon fibre construction to save weight. The exercise ball is placed front and center, serving as both the nose and landing gear of the aircraft. V-tails are used to place the rear control surfaces outside of the shadow of the ball, to help maintain control authority. Initial tests of the airframe showed handling problems. The team solved this by using a pair of gyro stabiliser boards of their own design, named Aura.
If you’ve ever had surgery, and you’re over a certain age, chances are good you’re familiar with the dreaded incentive spirometer. It’s a little plastic device with one or more columns, each of which has a plastic ball in it. The idea is to blow into the thing to float the balls, to ensure that your lungs stay in good shape and reduce the chance of pneumonia. This unique air-powered clock reminds us a little of that device, without all the pain.
Like a spirometer, [Nir Tasher]’s clock has three calibrated tubes, each big enough to hold a foam ball loosely. At the bottom of each tube is a blower whose motor is under PWM control. A laser rangefinder sits below each ball and measures its height; the measurement is used by a PID loop to control the speed of each fan and thus the height of each ball. The video below shows that the balls are actually pretty steady, making the clock easy to read. It doesn’t, however, reveal what the clock sounds like; we’re going to go out on a limb here and guess that it’s pretty noisy. Still, we think it’s a fantastic way to keep time, and unique in the extreme.
Who among us didn’t spend some portion of their youth trying in vain to watch a scrambled premium cable TV channel or two? It’s a wonder we didn’t blow out our cones and rods watching those weird colors and wavy lines dance across the screen like a fever dream.
In the early days of national premium television in America, anyone who’d forked over the cash and erected a six-foot satellite dish in the backyard could tune in channels like HBO, Showtime, and the first 24-hour news network, CNN. Fed up with freeloaders, these channels banded together to encrypt their transmissions and force people to buy expensive de-scrambling boxes. On top of that, subscribers had to pay a monthly pittance to keep the de-scrambler working. Continue reading “Grey Gear: French TV Encryption, 1980s Style”→
The best thing about [Shane]’s DIY TV-B-Gone is the strength of signal, though the size is nothing to sneeze at. That’s a 10-watt array or IR LEDs out of a security camera, and you can see how much brighter it is than a single IR LED in the video after the break.
Packed inside this minty enclosure is an Arduino Nano, which holds all the TV power-off codes known to hackers and fires them off in quick succession. [Shane] salvaged a MOSFET from an electronic speed controller to drive that LED array, and there’s a voltage booster board to raise the 3.7V lithium battery to 5V. [Shane] hasn’t really had the chance to test this out in public what with the global pandemic and all, but was able to verify a working distance of 40 feet inside the house.