Hackaday Prize Entry: DIY ARM Scientific Calculator

April 20, 2017 by 59 Comments

What does a hacker do when he or she wants something but can’t afford it? They hack one together, of course. Or, in the case of [Ramón Calvo], they thoughtfully plan and prototype. [Ramón Calvo] wanted a scientific calculator, but couldn’t afford one, so he designed and built one himself.

[Ramón] started off with Arduino but upgraded initially to Freescale’s Freedom KL25Z development board upgraded to an ARM Cortex-M0+ programmed using mbed. The display is an Electronic Assembly DOGL-128 128×64 pixel LCD. [Ramón] did a couple of iterations on the PCB, going from a large DIY one in order for the Arduino version to work, to the current, smaller version for the ARM chip with hand soldered SMD components. After that, [Ramón] looked into the algorithms needed to parse mathematical input. He settled on the shunting-yard algorithm, which converts the input into Reverse Polish Notation (RPN), which is easier for the software to work with.

[Ramón] has a ton of features working, including your standard add, subtract, multiply and divide operations, square root, nth root and exponentiation, trigonometry, log and log10, and factorial(!) There are a few things still on the to-do list, such as low power and a graphing mode, and there are a couple of bugs still in the system, but the overall system is up and running. [Ramón] has put up the schematic and KiCAD files up on his Hackaday.io project page along with the bill of materials.

We’ve had a few Hackaday prize entries in the form of calculators, such as this one with Nixie tubes and this one that emulates 70’s HP calculators.

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Pi Network Attenuators: Impedance Matching For The Strong Of Signal

April 20, 2017 by 29 Comments

If you catch a grizzled old radio amateur propping up the bar in the small hours, you will probably receive the gravelly-voiced Wisdom of the Ancients on impedance matching, antenna tuners, and LC networks. Impedance at RF, you will learn, is a Dark Art, for which you need a lifetime of experience to master. And presumably a taste for bourbon and branch water, to preserve the noir aesthetic.

It’s not strictly true, of course, but it is the case that impedance matching at RF with an LC network can be something of a pain. You will calculate and simulate, but you will always find a host of other environmental factors getting in the way when it comes down to achieving a match. Much tweaking of values ensues, and probably a bit of estimating just how bad a particular voltage standing wave ratio (VSWR) can be for your circuit.

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Giant Solderless LEGO NES Controller Gives Everyone Tiny Hands

April 20, 2017 by 13 Comments

If you were thinking “I should spend $130 on LEGO bricks and build a giant USB NES controller just to see what that would be like,” but you were afraid of spending that much money, [BrownDogGadgets] has you covered. He built a giant NES controller out of LEGO. The controller is designed in LEGO Digital Designer, which lets you create a virtual model, then get a full list of parts which can be ordered online.

The electronics are based on a Teensy LC programmed to appear as a USB keyboard, and the buttons are standard push buttons. The insides are wired together with nylon conductive tape. LEGO was an appropriate choice because the Teensy and switches are built on top of LEGO compatible PCBs, so components are just snapped in place. The system is called Crazy Circuits and is a pretty neat way to turn electronics into a universal and reusable system.

If that controller is too big, they’ve also used the same circuit with some laser cut parts for your own controller. If you do want to go even bigger, take a look at [Baron von Brunk’s] LEGO NES controller, which used the electronics from a real controller.

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Automate The Freight: Drones Across The Sea

April 20, 2017 by 105 Comments

When you think about which of the many technological advances of the 20th century had the most impact on the global economy, which one would you rank as the most important? Would it be the space program, which gave rise to advances in everything from communications satellites to advanced composite materials? Or would it be the related aerospace industry, which stitched the world together so tightly that you can be almost anywhere on the planet within 24 hours? Or perhaps it’s the Internet, the global platform for buying almost anything from almost anyone.

Those are all important, but for the most economically impactful technology of the 20th century, I’d posit that the lowly shipping container and the containerized cargo industry that grew around it win, hands down.

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E-ink Display Driven DIY

April 20, 2017 by 44 Comments

E-ink displays are awesome. Humans spent centuries reading non-backlit devices, and frankly it’s a lot easier on the eyes. But have you looked into driving one of these critters yourself? It’s a nightmare. So chapeau! to [Julien] for his FPGA-based implementation that not only uses our favorite open-source FPGA toolchain, and serves as an open reference implementation for anyone else who’s interested.

Getting just black and white on an E-ink display is relatively easy — just hit the ink pixels with the same signal over and over until they give up. Greyscale is made by applying much more nuanced voltages because the pixels are somewhat state-dependent. If the desired endpoint is a 50% grey, for instance, you’d hit it with a different pulse train if the pixel were now white versus if it were now black. (Ever notice that your e-book screen periodically does a white-black flash? It’s resetting all the pixels to a known state.) And that’s not even taking into account the hassles with the various crazy voltages that E-ink displays require, which [Julien] wisely handed off to a dedicated chip.

In the end, the device has to make 20-50 passes through the screen for one user-visible refresh. [Julien] found that the usual microcontrollers just weren’t capable of the speed that he wanted, hence the FPGA and custom waveform tables. We’ve seen E-ink hacks before, and [Julien] is standing on the shoulders of giants, most notably those of [Petteri Aimonen] and [Sprite_tm]. [Julien]’s hack has the fastest updates we’ve ever seen.

We still can’t wait for the day that there is a general-purpose E-ink driver chip out there for pennies, because nearly every project we make with a backlit display would look better, and chew through the batteries slower, with E-ink. In the meantime, [Julien]’s FPGA implementation is pretty close, and it’s fully open.

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Learn A Language, One Moment At A Time

April 20, 2017 by 20 Comments

There’s a lot of times in an average day when you’ll find yourself waiting. Waiting for your morning brew at the cafe, or for an email to show up — it’s often just a few minutes, many times a day. It’s far too short a time to get any real work done, but it adds up at the end of the week.

Enter WaitSuite, a language learning tool developed by MIT’s CSAIL. It’s a language learning tool, which aims to teach users words in a foreign language in these “micromoments” — the short periods of time spent waiting each day. The trick to WaitSuite here is in its ultralightweight design which integrates into other tasks and software on your computer and smartphone. Rather then having to launch a separate app, which takes time and effort, WaitSuite hovers in the background, ready to go when it detects a short period of wait time. Examples given are hitting refresh in Gmail, or waiting for a connection to a WiFi network.

The team behind the project calls this concept wait-learning; you can read the paper here. If you’d like to try it out, use the Chrome extension called WaitChatter. It quizzes you while you’re waiting on a response in GChat. We’d love to see the rest of the WaitSuite released publicly soon.

It’s a tidy piece of software that’s great for those looking for an alternative to compulsively refreshing social media while loitering. It probably won’t help you learn French overnight, but it could be a useful way to pick up some extra vocab without having to carve more time out of your schedule.

We don’t see a whole lot of language learning hacks here, but you might like to check out Adafruit’s take on the Babel Fish.

Go Wireless With This DIY Laser Ethernet Link

April 19, 2017 by 40 Comments

Most of us have Ethernet in our homes today. The real backbones of the Internet though, use no wires at all. Optical fibers carry pulses of light across the land, under the sea, and if you’re lucky, right to your door. [Sven Brauch] decided to create an optical link. He didn’t have any fiber handy, but air will carry laser pulses over short distances quite nicely. The idea of this project is to directly convert ethernet signals to light pulses. For simplicity’s sake, [Sven] limited the bandwidth to one channel, full-duplex, at 10 Megabits per second (Mbps).

The transmit side of the circuit is rather simple. An op-amp circuit acts as a constant current source, biasing the laser diode. The transmit signal from an Ethernet cable is then added in as modulation. This ensures the laser glows brightly for a 1 bit but never shuts completely off for a 0 bit.

The receive side of the circuit starts with a photodiode. The diode is biased up around 35 V, and a transimpedance amplifier (a current to voltage converter) is used to determine if the diode is seeing a 1 or a 0 from the laser. A bit more signal conditioning ensures the output will be a proper differential Ethernet signal.

[Sven] built two identical boards – each with a transmitter and receiver. He tested the circuit by pointing it at a mirror. His Linux box immediately established a link and was reported that there was a duplicate IP address on the network. This was exactly what [Sven] expected. The computer was confused by its own reflection – but the laser and photodiode circuits were working.

Finally, [Sven] connected his PC and a Raspberry Pi to the two circuits. After carefully aligning the lasers on a wooden board, the two machines established a link. Success! (But be aware that a longer distances, more sophisticated alignment mechanisms may be in order.)

Want to know more about fiber and networking? Check out this article about wiring up an older city. You can also use an optical link to control your CNC.