We’ve never seen someone build a plotter out of buzzwords, but [roxen] did a really good job of it. The idea is simple, place the plotter over a sheet of paper, open a website, draw, and watch the plotter go. Check out the video below the break.
The user draws in an HTML5 Canvas object which is read by a Java Web Server. From there it gets converted to serial commands for an Arduino which controls the steppers with two EasyDrivers.
The build itself is really nice. It perfectly meets the mechanical requirements of a pen plotter without a lot of fluff. The overall frame is T-shaped, for the x- and y-axis. The movements are produced by two steppers and acetal rack and pinion sets. The pen is lifted up and down by a hobby servo.
Hernando Barragán is the grandfather of Arduino of whom you’ve never heard. And after years now of being basically silent on the issue of attribution, he’s decided to get some of his grudges off his chest and clear the air around Wiring and Arduino. It’s a long read, and at times a little bitter, but if you’ve been following the development of the Arduino vs Arduino debacle, it’s an important piece in the puzzle.
Wiring, in case you don’t know, is where digitalWrite() and company come from. Maybe even more importantly, Wiring basically incubated the idea of building a microcontroller-based hardware controller platform that was simple enough to program that it could be used by artists. Indeed, it was intended to be the physical counterpart to Processing, a visual programming language for art. We’ve always wondered about the relationship between Wiring and Arduino, and it’s good to hear the Wiring side of the story. (We actually interviewed Barragán earlier this year, and he asked that we hold off until he published his side of things on the web.)
The short version is that Arduino was basically a fork of the Wiring software, re-branded and running on a physical platform that borrowed a lot from the Wiring boards. Whether or not this is legal or even moral is not an issue — Wiring was developed fully open-source, both software and hardware, so it was Massimo Banzi’s to copy as much as anyone else’s. But given that Arduino started off as essentially a re-branded Wiring (with code ported to a trivially different microcontroller), you’d be forgiven for thinking that somewhat more acknowledgement than “derives from Wiring” was appropriate.
The story of Arduino, from Barragán’s perspective, is actually a classic tragedy: student comes up with a really big idea, and one of his professors takes credit for it and runs with it.
Before the NSA deletes this post, we’ll be clear: We’re talking about a model of a nuclear reactor, not the real thing. Using Legos, [wgurecky] built a point kinetic reactor model that interfaces with the reactor simulator, pyReactor.
Even without the Lego, the Python code demonstrates reactor control in several modes. In power control mode, the user sets a power output, and the reactor attempts to maintain it. In control rod mode, the user can adjust the position of the control rods and see the results.
If things get out of hand, there’s a SCRAM button to shut the reactor down in a hurry. The Lego model uses an Arduino to move the rods up and down (using a servo) and controls the simulated Cherenkov radiation (courtesy of blue LEDs).
We’ve been excited to see more high schools with significant engineering programs. This would be a good project for kids interested in nuclear engineering. It certainly is a lot safer than one of our previous reactor projects.
Snow skiing looks easy, right? You just stay standing, and gravity does the work. The reality is that skiing is difficult for beginners to learn. [19mkarpawich] loves to ski, but he was frustrated seeing crying kids on skis along with screaming parents trying to coach them. Inspired by wearable electronics, he took an Arduino, an old jacket, some LEDs, and created Ski Buddy.
First-person-view (FPV) flying, by adding a camera, video transmitter, and video goggles to the meat on the ground, is one of the best ways to experience remote-controlled flight. For just a few hundred dollars, it’s the closest thing you’re going to get to growing wings and flying through the trees of your local park. One of the most popular and cheapest ways to go about this is the Boscam RX5808 wireless receiver – a $9 module able to pull down video from an aircraft over 5.8GHz radio. Stock, this radio module is just okay, but with a few modifications, it can be turned into a very good receiver with a spectrum analyzer and autoscan.
The Boscam RX5808 has three DIP switches to allow for eight different channels for receiving video, and this is where most RC hobbyists stop. But the module also has a very capable SPI interface, and by adding a simple Arduino, the complete capabilities of this receiver can be unlocked.
The core software for the build is [markohoepken]’s rx5808-pro and rx5808_pro_osd, and [crazyheea]’s rx5808-pro-diversity to enable all the capabilities available in the RX5808 receiver. With an off-the-shelf LCD, this mess of wires and boards turns into an auto-scanning spectrum analyzer that’s also able to put video from a drone onto a screen.
[garagedrone] put together a very complete demo video of the entire build. You can check that out below.
[JAC_101], the Director of Legal Evil Emeritus for LVL1 Hackerspace (don’t ask me, it’s their title system), was challenged to a hacking duel. It all started years ago. The person who is now president of LVL1, visited the space for the first time and brought with her a discarded Apple II controller for Lego bricks which had previously belonged to her father. Excited to test it, the space found that, unfortunately, LVL1’s Apple II wouldn’t boot. An argument ensued, probably some trash talking, and [JAC_101] left with the challenge: Could he build an Arduino interface for the Apple II Lego controller quicker than the hackerspace could fix its Apple II?”
In the end, a concentrated force by one hacker over two years overcame the collective ADHD of many. He began by opening the interface to look inside, a completely unnecessary step since he found it was already thoroughly documented. Next he forgot about the project for a year. Then he remembered it, and built an interface for an Arduino Uno to hook to the controller and wrote a library for the interface. Realizing that sending serial commands was not in line with the original friendly intention of the device, he added a graphical display to the project; which allowed the user to control the panel with touch. In the end he won the challenge and LVL1 still doesn’t have a working Apple II. We assume some gloating occurred. Some videos of it in action after the break.
It was Stardate 2267. A mysterious life form known as Redjac possessed the computer system of the USS Enterprise. Being well versed in both computer operations and mathematics, [Spock] instructed the computer to compute pi to the last digit. “…the value of pi is a transcendental figure without resolution” he would say. The task of computing pi presents to the computer an infinite process. The computer would have to work on the task forever, eventually forcing the Redjac out.
Calculus relies on infinite processes. And the Arduino is a (single thread) computer. So the idea of running a calculus function on an Arduino presents a seemingly impossible scenario. In this article, we’re going to explore the idea of using derivative like techniques with a microcontroller. Let us be reminded that the derivative provides an instantaneous rate of change. Getting an instantaneous rate of change when the function is known is easy. However, when you’re working with a microcontroller and varying analog data without a known function, it’s not so easy. Our goal will be to get an average rate of change of the data. And since a microcontroller is many orders of magnitude faster than the rate of change of the incoming data, we can calculate the average rate of change over very small time intervals. Our work will be based on the fact that the average rate of change and instantaneous rate of change are the same over short time intervals.