A Mobile Terminal For Guerrilla Communications

May 4, 2018 by Tom Nardi 25 Comments

We use the Internet to do everything from filing our taxes to finding good pizza, but most critically it fulfills nearly all of our communication needs. Unfortunately, this reliance can be exploited by those pulling the strings; if your government is trying to do something shady, the first step is likely to be effecting how you can communicate with the outside world. The Internet is heavily censored and monitored in China, and in North Korea the entire country is effectively running on an intranet that’s cutoff from the wider Internet. The need for decentralized information services and communication is very real.

While it might not solve all the world’s communication problems, [::vtol::] writes in to tell us about a very interesting communication device he’s been working on that he calls “Hot Ninja”. Operating on the principle that users might be searching for accessible Wi-Fi networks in a situation where the Internet has been taken down, Hot Ninja allows the user to send simple messages through Wi-Fi SSIDs.

We’ve all seen creatively named Wi-Fi networks before, and the idea here is very much the same. Hot Ninja creates a Wi-Fi network with the user’s message as the SSID in hopes that somebody on a mobile device will see it. The SSID alone could be enough depending on the situation, but Hot Ninja is also able to serve up a basic web page to devices which actually connect. In the video after the break, [::vtol::] even demonstrates some rudimentary BBS-style functionality by presenting the client devices with a text field, the contents of which are saved to a log file.

In terms of hardware, Hot Ninja is made up of an Arduino Mega coupled to three ESP8266 boards, and a battery to keep it all running for up to eight hours so you can subvert a dictatorship while on the move. The user interface is provided by a small OLED screen and a keyboard made entirely of through-hole tactile switches, further reinforcing the trope that touch-typing will be a must have skill in the dystopian future. It might not be the most ergonomic device we’ve ever seen, but the fact it looks like something out of a Neal Stephenson novel more than makes up for it in our book.

This is not the first time we’ve seen Wi-Fi SSIDs used as a method of communication, thanks largely to how easy the ESP8266 makes it. For his part, [::vtol::] has previously experimented with using them to culturally enrich the masses.

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Reviving An Electron Microscope With Arduino

April 7, 2018 by Tom Nardi 20 Comments

We don’t know about you, but when our friends ask us if we want to help them fix something, they’re usually talking about their computer, phone, or car. So far it’s never been about helping them rebuild an old electron microscope. But that’s exactly the request [Benjamin Blundell] got when a friend from a local hackerspace asked if he could take a look at a vintage Cambridge Stereoscan 200 they had found abandoned in a shed. Clearly we’re hanging out with the wrong group of people.

As you might imagine, the microscope was in desperate need of some love after spending time in considerably less than ideal conditions. While some of the hackerspace members started tackling the hardware side of the machine, [Benjamin] was tasked with finding a way to recover the contents of the scope’s ROM. While he’s still working on verification, the dumps he’s made so far of the various ROMs living inside the Stereoscan 200 have been promising and he believes he’s on the right track.

The microscope uses a mix of Texas Instruments 25L32 and 2516 chips, which [Benjamin] had to carefully pry out after making sure to document everything so he knew what went where. A few of the chips weren’t keen on being pulled from their home of 30-odd years, so there were a few broken pins, but on the whole the operation was a success.

Each chip was placed in a breadboard and wired up to an Arduino Mega, as it has enough digital pins to connect without needing a shift register. With the wiring fairly straightforward, [Benjamin] just needed to write up some code to read the contents of the chip, which he has graciously provided anyone else who might be working on a similar project. At this point he hasn’t found anything identifiable in his ROM dumps to prove that they’ve been made successfully, all he really knows right now is that he has something. At least it’s a start.

More and more of these older electron microscopes are getting a second lease on life thanks to dedicated hackers in their home labs. Makes you wonder if there’s ever going to be a piece of hardware the hacker community won’t bend to their will.

RGB Disk Goes Interactive With Bluetooth; Shows Impressive Plastic Work

March 11, 2018 by Donald Papp 5 Comments

[smash_hand] had a clear goal: a big, featureless, white plastic disk with RGB LEDs concealed around its edge. So what is it? A big ornament that could glow any color or trippy mixture of colors one desires. It’s an object whose sole purpose is to be a frame for soft, glowing light patterns to admire. The disk can be controlled with a simple smartphone app that communicates over Bluetooth, allowing anyone (or in theory anything) to play with the display.

The disk is made from 1/4″ clear plastic, which [smash_hand] describes as plexiglass, but might be acrylic or polycarbonate. [smash_hands] describes some trial and error in the process of cutting the circle; it was saw-cut with some 3-in-1 oil as cutting fluid first, then the final shape cut with a bandsaw.

The saw left the edge very rough, so it was polished with glass polishing compound. This restores the optical properties required for the edge-lighting technique. The back of the disc was sanded then painted white, and the RGB LEDs spaced evenly around the edge, pointing inwards.

The physical build is almost always the difficult part in a project like this — achieving good diffusion of LEDs is a topic we talk about often. [smash_hands] did an impressive job and there are never any “hot spots” where an LED sticks out to your eye. With this taken care of, the electronics came together with much less effort. An Arduino with an HC-05 Bluetooth adapter took care of driving the LEDs and wireless communications, respectively. A wooden frame later, and the whole thing is ready to go.

[smash_hands] provides details like a wiring diagram as well as the smartphone app for anyone who is interested. There’s the Arduino program as well, but interestingly it’s only available in assembly or as a raw .hex file. A video of the disk in action is embedded below.

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Debugging With Serial Print At 5333333 Baud

February 25, 2018 by Donald Papp 28 Comments

Debugging with printf is something [StorePeter] has always found super handy, and as a result he’s always been interested in tweaking the process for improvements. This kind of debugging usually has microcontrollers sending messages over a serial port, but in embedded development there isn’t always a hardware UART, or it might already be in use. His preferred method of avoiding those problems is to use a USB to Serial adapter and bit-bang the serial on the microcontroller side. It was during this process that it occurred to [StorePeter] that there was a lot of streamlining he could be doing, and thanks to serial terminal programs that support arbitrary baud rates, he’s reliably sending debug messages over serial at 5.3 Mbit/sec, or 5333333 Baud. His code is available for download from his site, and works perfectly in the Arduino IDE.

The whole thing consists of some simple, easily ported code to implement a bare minimum bit-banged serial communication. This is output only, no feedback, and timing consists of just sending bits as quickly as the CPU can handle, leaving it up to the USB Serial adapter and rest of the world to handle whatever that speed turns out to be. On a 16 MHz AVR, transmitting one bit can be done in three instructions, which comes out to about 5333333 baud or roughly 5.3 Mbit/sec. Set a terminal program to 5333333 baud, and you can get a “Hello world” in about 20 microseconds compared to 1 millisecond at 115200 baud.

He’s got additional tips on using serial print debugging as a process, and he’s done a followup where he stress-tests the reliability of a 5.3 MBit/sec serial stream from an ATMega2560 at 16 MHz in his 3D printer, and found no missed packets. That certainly covers using printf as a debugger, so how about a method of using the debugger as printf?

Cable Cutting Machine Makes Fast Work Of A Tedious Job

January 14, 2018 by Dan Maloney 22 Comments

We’ve all been there: faced with a tedious job that could be knocked out manually with a modest investment of time, we choose instead to overcomplicate the task and build something to do it for us. Such was the impetus behind this automated wire cutter, but in this case the ends justify the means.

That [Edward Carlson] managed to stretch a twenty-minute session with wire cutters and a tape measure into four days of building and tweaking this machine is pretty impressive. The build process was jump-started by modifying an off-the-shelf wire measuring machine, of the kind one finds in the electrical aisle of The Big Orange Store. Stripped of the original mechanical totalizer and with a stepper added to drive the friction wheels, the machine can now measure cable by counting steps. A high-torque servo drives a stout pair of cable shears through a nifty linkage, or the machine can just measure the length of cable without cutting. [Edward]’s solution in search of a problem ends up bringing extra value, so maybe the time spent was worth it after all.

If the overall design looks familiar, you may be thinking of a similar of another cable-cutting bot we featured a while back. That one used a filament extruder and was for lighter gauge wires than this machine. Continue reading “Cable Cutting Machine Makes Fast Work Of A Tedious Job” →

A Stepper Motor For Two Dimensions

January 8, 2018 by Dan Maloney 47 Comments

We’ve all heard linear motors, like those propelling Maglev trains, described as “unrolled” versions of regular electric motors. The analogy is apt and helps to understand how a linear motor works, but it begs the question: what if we could unroll the stator in two dimensions instead of just one?

That’s the idea behind [BetaChecker’s] two-axis stepper motor, which looks like it has a lot of potential for some interesting applications. Build details are sparse, but from what we can gather from the videos and the Hackaday.io post, [BetaChecker] has created a platen of 288 hand-wound copper coils, each of which can be selectively controlled through a large number of L293 H-bridge chips and an Arduino Mega. A variety of sleds, each with neodymium magnets in the base, can be applied to the platen, and depending on how the coils are energized, the sled can move in either dimension. For vertical applications, it looks like some coils are used to hold the sled to the platen while others are used to propel it. There are RGB LEDs inside the bore of each coil, although their function beyond zazzle is unclear.

We’d love more details to gauge where this is going, but with better resolution, something like this could make a great 3D-printer bed. If one-dimensional movement is enough for you, though, check out this linear stepper motor that works on a similar principle.

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OpenBraille Is An Impressive DIY Embosser

January 3, 2018 by Kristina Panos 9 Comments

In 2024, the Braille system will have been around for 200 years. What better way to mark the occasion than with an open source project devoted to making embossing equipment affordable for the visually impaired? This long overdue cause became the plight of [ccampos7], who couldn’t find a DIY embosser kit and set out to build one himself.

While other embossers forcibly punch the letters in one go, OpenBraille takes a more gradual approach to ensure a clean impression with a rolling motion. Paper is placed between a mechanical encoder with moving pins and a dimpled roller that provides resistance and a place to land. The embossing head is driven by an Arduino Mega and a standard RAMPS board, as the rest of the system relies on Cartesian movement.

The encoder mechanism itself is pretty interesting. A micro servo drives a 3D printed wheel with three distinct tracks around half of the edge. The peaks and valleys encoded in these plastic tracks actuate the embossing pins, which are made from nails embedded through the sides of hex nuts. There’s a quick demo of the encoder movement after the break, and another video of it in action on the OpenBraille Facebook page.

[ccampos7] has all the files up on Thingiverse and plans to post the software soon. You should also check out this compact embosser that was recognized in the first round of the 2017 Hackaday Prize which is a nice all-print Braille concept. Continue reading “OpenBraille Is An Impressive DIY Embosser” →