Prime Numbers Are Stranger Than You Thought

March 14, 2016 by 135 Comments

If you’ve spent any time around prime numbers, you know they’re a pretty odd bunch. (Get it?) But it turns out that they’re even stranger than we knew — until recently. According to this very readable writeup of brand-new research by [Kannan Soundararajan] and [Robert Lemkein], the final digits of prime numbers repel each other.

More straightforwardly stated, if you pick any given prime number, the last digit of the next-largest prime number is disproportionately unlikely to match the final digit of your prime. Even stranger, they seem to have preferences. For instance, if your prime ends in 3, it’s more likely that the next prime will end in 9 than in 1 or 7. Whoah!

Even spookier? The finding holds up in many different bases. It was actually first noticed in base-three. The original paper is up on Arxiv, so go check it out.

This is a brand-new finding that’s been hiding under people’s noses essentially forever. The going assumption was that primes were distributed essentially randomly, and now we have empirical evidence that it’s not true. What this means for cryptology or mathematics? Nobody knows, yet. Anyone up for wild speculation? That’s what the comments section is for.

(Headline photo of researchers Kannan Soundararajan and Robert Lemke: Waheeda Khalfan)

Engineer Humanity’s Future: The 2016 Hackaday Prize

March 14, 2016 by 61 Comments

Today we are proud to launch the 2016 Hackaday Prize. Build Something That Matters and you’ll contribute positively to humanity’s future by expand the frontiers of knowledge and engineering. You’ll also score recognition of your skills, and position yourself to land one of 105 cash prizes totaling over $300,000. Choose a technology issue facing humanity today and build a project that fixes, improves, or bypasses the problem.

You have the talent, the energy, and the capacity to change the world. Make the time and make a difference.

The Hackaday Prize is a competition synonymous with creating for social change. Using your hardware, coding, scientific, design and mechanical abilities, you will make big changes in people’s lives. Every idea has impact, and a massive force of ideas creates real change. This year we have more power than ever before to recognize the engineering projects that are solving problems: One hundred finalists will get $1,000 each for their efforts. This flat prize structure encourages collaboration rather than direct competition. Team up on each others’ projects and improve your overall chances of making it into the finals.

But it doesn’t stop there. From one hundred finalists, five will rise to be named top winners. Our expert judges will carefully review each of 100 world-changing final entries, choosing a grand prize winner to receive $150,000. Second place will be awarded $25,000, with $10k, $10k, and $5k going to third, fourth, and fifth.

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TrainLight: Transit Info At A Glance

March 14, 2016 by 7 Comments

In a world of sensory overload, sometimes it’s nice to get the information you need without a bunch of clutter. [Savage] has created an attractive and minimalist system to display the current wait times for specific trains in his San Francisco neighborhood.

trainlight-legendIt’s basically a Spark Core and a 60 LED-per-meter strip of WS2812Bs. A 1000µF cap filters the power coming in from a switching adapter and a resistor limits the level-shifted logic going to the LEDs. Eight barriers made from card stock keep the light zones from bleeding together. The sides of the square canvas panel indicate cardinal directions and are oriented to [Savage]’s southern-facing house.

The server gets prediction data every 30 seconds using the RESTbus JSON API. [Savage] added in a bit of time for walking down the stairs, putting shoes on, and walking to each stop. TrainLight receives these times over WiFi and lights the LEDs accordingly. If a section isn’t lit at all, the wait time for that line is greater than 10 minutes. Dark green means you have 5-10 minutes to get there, and pale green means 2-5 minutes. If the LEDs are yellow, you’d better put on your running shoes.

This is a fairly simple build with a focus on subtlety. Even before guests in his house understand what they’re looking at, [Savage]’s TrainLight makes for an interesting conversational piece of blinkenlights and doubles as illumination for the stairs. There’s a slightly sped-up demo after the break.

Want to make your own? [Savage] has a tutorial page and his code is up on the gits. Blinky lights are also good for telling you whether the trains are running at all.

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Broken RC Car Goes Online

March 14, 2016 by 22 Comments

When the remote for your son’s RC car goes missing, what are you going to do? Throw away a perfectly good robot chassis? No, we wouldn’t either. And these days, with WiFi-enabled microcontroller boards so readily available, it’s almost easier to network the thing than it would be to re-establish radio control. So that’s just what [Stian Søreng] did.

Naturally, there’s an ESP8266 board at the heart of this hack, a WeMos D1 to be specific. [Stian] had played with cheap remote-controlled cars enough to be already familiar with the pinout of the RC IC, so he could simply hook up some GPIOs from the WeMos board to the pins and the brain transplant was complete.

On the software side, he implemented control over TCP by sending the characters “F”, “B”, “L”, or “R” to send the car forward, back, left, or right. Lowercase versions of the same letters turns that function off. He then wrote some client software in Qt that sends the right letters. He says that response time is around 150-250 ms, but that it works for his driving style — crashing. (We’d work on that.)

Anyway, it’s a fun and fairly quick project, and it re-uses something that was destined for the junk heap anyway, so it’s a strict win. The next steps are fairly open. With computer control of the car, he could do anything. What would you do next?

Thanks [Eyewind] for the tip!

Petite Package Provides Powerful Robot

March 13, 2016 by 5 Comments

The Robot Operating System (ROS) is typically associated with big robots but [Grassjelly] decided to prove differently by creating Linorobot. This small, differential drive robot is similar in appearance to many small Arduino based robots often used for line following. Linorobot packs a lot more computing power with a Teensy 3.1 connected to a Radxa Rock Pro. The Teensy handles the motors, reading their encoders, and acquisition of IMU data.

The Radxa, new to us here at Hackaday, is a single board computer based on the quad-core ARM Cortex-A9 1.6 GHz CPU. It may not have been seen on our pages but if you’re at Hackaday Belgrade you can attend a session on building a cluster using it. The ability to run Linux is key to using ROS, which is an open source system for controlling robots. With the Radxa running ROS it interfaces directly to the Neato XV-11 Lidar’s dedicated controller board.

Avoiding the hand.
Mapping with lidar.

The Linorobot packs into a small robot the capabilities usually seen in much larger and expensive robots such as the Turtlebot 2. With this diminutive robot hackers can learn about doing SLAM (Simultaneous Localization and Mapping) and autonomous navigation, plus the other capabilities of ROS.

[Grassjelly] has a tutorial on building the robot which is also a good introduce to ROS. He provides the software as open source. It’s an impressive project which provides a small, comparatively affordable robot for learning and working with ROS. A video of Linorobot SLAMing and navigating [Grassjelly’s] lab is after the break.

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EKG Business Card Warms Our Hearts

March 13, 2016 by 32 Comments

Giving out a paper business card is so 1960s. Giving out a PCB business card, well that gets you up to the early 2010s. If you really want to stand out these days, give them a fully-functional EKG in a business card. (Note: works best if you’re leading an open-source electrocardiography project.)

Looking through the schematics (PDF), there’s not much to the card. At the center of everything is an ADuC7061, which is an ARM microprocessor equipped with 24-bit ADCs that also has an internal DAC-driven voltage reference connected to one of the user’s thumbs. This, plus a little buffering circuitry, seems to be enough to translate the tiny voltage potential difference across your two hands into a beautiful signal on the included OLED display. Very nice!

Everything (including the big version of their EKG) is open source and made on an open toolchain. If you’re interested in health and medical sensing, you should head over to the project’s GitHub and check it out. The standalone open EKG is based on a much more complicated circuit, and stands to be more accurate. But the business card version is just soooo cute!

Thanks [Ag Primatic] for the tip!

Hackaday Links: March 13, 2016

March 13, 2016 by 26 Comments

Way back in 2014, Heathkit was a mystery. We knew someone was trying to revive the brand, but that was about it. Adafruit pulled out all the stops to solve this mystery and came up with nothing. The only clue to the existence of Heathkit was a random person who found a geocache in Brooklyn Bridge Park. Since then, Heathkit has released an odd AM radio kit and $150 antenna. These offerings only present more mysteries, but at least [Paul] was finally rewarded for finding the Heathkit geocache. Heathkit sent [Paul] the AM radio kit. He says it’s neat and well documented.

[David] is doing his masters thesis on, “The motivation of the maker community”. That means empirical data, and that (usually) means surveymonkey. You can take his survey on the motivations of the maker community here.

America’s best loved companies, Verizon and Makerbot, together at last.

The BeagleBone Black was launched in 2013. The BeagleBone Green – a Seeed joint – showed up last August. The BeagleBone Blue, released just a few months ago, is a collaboration between the UCSD engineering department and TI. Now there’s the BeagleBone Enhanced. Yes, they should have picked another color. Perhaps ecru. The BB Enhanced sports one Gigabyte of RAM, Gigabit Ethernet, two USB ports and two USBs via an expansion header, optional serial NOR Flash for a bootloader, optional six-axis gyro, and optional barometer.

Atmel is changing a few AVRs. There is a new die for the ATMega 44, 88, 168, and the ‘Arduino chip’, the ATMega328. Most of the changes are relatively inconsequential – slightly higher current consumption in power save mode – but one of these changes is going to trip up a lot of people. The Device ID, also known as the source of the avrdude: initialization failed, rc=-1 error, has changed on a lot of chips.

Makeit Labs in Nashua, New Hampshire has a problem. They were awarded $250,000 in tax credits to help them move and renovate. Sounds like a very good problem, right? Not so: they need to sell these tax credits before the end of the month, or they lose them. They’re looking for a few businesses in New Hampshire to buy these tax credits. From [Peter Walsh]: “Under the credit program, a typical business donating $10,000 would save $9,000 on their state and federal taxes! That $10,000 donation would cost them only $1006!” Does that make sense? No, it’s taxes, of course not. If you’re a business in New Hampshire and are looking to reduce your tax burden, this is the solution.

So I mentioned MRRF, right? You should go to MRRF. It’s next weekend.