Card Reader Lockout Keeps Unauthorized Tool Users At Bay

May 20, 2018 by 19 Comments

It’s a problem common to every hackerspace, university machine shop, or even the home shops of parents with serious control issues: how do you make sure that only trained personnel are running the machines? There are all kinds of ways to tackle the problem, but why not throw a little tech at it with something like this magnetic card-reader machine lockout?

[OnyxEpoch] does not reveal which of the above categories he falls into, if any, but we’ll go out on a limb and guess that it’s a hackerspace because it would work really well in such an environment. Built into a sturdy steel enclosure, the guts are pretty simple — an Arduino Uno with shields for USB, an SD card, and a data logger, along with an LCD display and various buttons and switches. The heart of the thing is a USB magnetic card reader, mounted to the front of the enclosure.

To unlock the machine, a user swipes his or her card, and if an administrator has previously added them to the list, a relay powers the tool up. There’s a key switch for local override, of course, and an administrative mode for programming at the point of use. Tool use is logged by date, time, and user, which should make it easy to identify mess-makers and other scofflaws.

We find it impressively complete, but imagine having a session timeout in the middle of a machine operation would be annoying at the least, and potentially dangerous at worst. Maybe the solution is a very visible alert as the timeout approaches — a cherry top would do the trick!

There’s more reading if you’re one seeking good ideas for hackerspace. We’ve covered the basics of hackerspace safety before, as well as insurance for hackerspaces.

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Accessing Blockchain On ESP8266 Using The NodeMCU Board

May 2, 2018 by 24 Comments

Blockchains claim to be public, distributed, effectively immutable ledgers. Unfortunately, they also tend to get a little bit huge – presently the Bitcoin blockchain is 194GB and Ethereum weighs in at 444GB. That poses quite an inconvenience for me, as I was looking at making some fun ‘Ethereum blockchain aware’ gadgets and that’s several orders of magnitude too much data to deal with on a microcontroller, not to mention the bandwidth cost if using 3G.

Having imagined a thin device that I could integrate into my mobile phone cover (or perhaps… a wallet?) dealing with the whole blockchain was clearly not a possibility. I could use a VPS or router to efficiently download the necessary data and respond to queries, but even that seemed like a lot of overhead, so I investigated available APIs.

As it turns out, several blockchain explorers offer APIs that do what I want. My efforts get an ESP8266 involved with the blockchain began with two of the available APIs: Ethplorer and Etherscan.

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ETextile Spring Break Tackles Signal Blocking, Audio Generation, And Radio Transmissions

April 20, 2018 by 12 Comments

Finding a killer application for e-textiles is the realm of the hacker and within that realm, anything goes. Whether it’s protecting your digital privacy with signal shielding, generating audio with a wearable BeagleBone or 555 timer, or making your favorite garment into an antenna, the eTextile Spring Break is testing out ways to combine electronics and fabric.

You may be asking yourself “What are e-textiles good for?”. Well, that’s an excellent question and likely the most common one facing the industry today. I’m afraid I won’t be able to give a definitive answer. As an e-textile practitioner, I too am constantly posing this question to myself. There’s an inherently personal nature to fabric worn on the body and to our electronic devices that makes this answer elusive. Instead of trying to fabricate some narrow definition, what I offer is a look at topics of interest, material experimentation, and technical exploration through the lens of a week-long event held recently in New York called eTextile Spring Break.

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Eavesdropping On A VGA Monitor’s Conversations

March 29, 2018 by 28 Comments

Did you ever wonder what your monitor and your computer are talking about behind your back? As it turns out, there’s quite a conversation going on while the monitor and the computer decide how to get along, and sniffing out VGA communications can reveal some pretty fascinating stuff about the I²C protocol.

To reverse engineer the configuration information exchanged between a VGA monitor and a video card, [Ken Shirriff] began by lopping a VGA cable in two. The inside of such cables is surprisingly complex, with separate shielding wires for each color and sync channel and a host of control wires, all bundled in multiple layers of shielding foil and braid to reduce EMI. [Ken] identified the clock and data lines used for the I²C interface and broke those out into a PocketBeagle for analysis using the tiny Linux machine’s I²C tools.

With a Python script to help decode the monitor’s Extended Display Identification Data (EDID) data, [Ken] was able to see everything the monitor knows about itself — manufacturer, serial number, all the supported resolution modes, and even deprecated timing and signal information left over from the days when CRTs ruled the desktop. Particularly interesting are the surprisingly limited capabilities of a VGA display in terms of color reproduction, as well as [Ken]’s detailed discussion on the I²C bus in general and how it works.

We always enjoy these looks under the hood that [Ken] is so good at, and we look forward to his reverse engineering write-ups. His recent efforts include a look at core memory from a 50-year old mainframe and reverse engineering at the silicon level.

Review: LimeSDR Mini Software Defined Radio Transceiver

March 13, 2018 by 56 Comments

It’s fair to say that software-defined radio represents the most significant advance in affordable radio equipment that we have seen over the last decade or so. Moving signal processing from purpose-built analogue hardware into the realm of software has opened up so many exciting possibilities in terms of what can be done both with more traditional modes of radio communication and with newer ones made possible only by the new technology.

It’s also fair to say that radio enthusiasts seeking a high-performance SDR would also have to be prepared with a hefty bank balance, as some of the components required to deliver software defined radios have been rather expensive. Thus the budget end of the market has been the preserve of radios using the limited baseband bandwidth of an existing analogue interface such as a computer sound card, or of happy accidents in driver hacking such as the discovery that the cheap and now-ubiquitous RTL2832 chipset digital TV receivers could function as an SDR receiver. Transmitting has been, and still is, more expensive.

The LimeSDR Mini's chunky USB stick form factor.
The LimeSDR Mini’s chunky USB stick form factor.

A new generation of budget SDRs, as typified by today’s subject the LimeSDR Mini, have brought down the price of transmitting. This is the latest addition to the LimeSDR range of products, an SDR transceiver and FPGA development board in a USB stick format that uses the same Lime Microsystems LMS7002M at its heart as the existing LimeSDR USB, but with a lower specification. Chief among the changes are that there is only one receive and one transmit channel to the USB’s two each, the bandwidth of 30.72 MHz is halved, and the lower-end frequency range jumps from 100 kHz to 10 MHz. The most interesting lower figure associated with the Mini though is its price, with the early birds snapping it up for $99 — half that of its predecessor. (It’s now available on Kickstarter for $139.)

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A Talking Clock For The 21st Century

January 27, 2018 by 24 Comments

The Talking Clock service is disappearing, and it’s quite possible that few of you will be aware of its passing. One of the staples of twentieth-century technology, the Talking Clock service was the only universally consumer-available source of accurate time information away from hourly radio time signals in the days before cheap radio-controlled clocks, or GPS. You’d dial (on a real dial, naturally!) a telephone number, to be greeted with a recorded voice telling you what the time would be at the following beep. Clocks were set, phone companies made a packet, and everybody was happy with their high-tech audio horology.

[Nick Sayer] used the USNO Master Clock telephone feed to see in the New Year, but had to make do with a voice from another time zone. It seems that there are no services remaining that provide one in Pacific time. His solution to the problem for a future year? Make his own Talking Clock, one that derives its time reference from GPS.

At its heart is a SkyTraq Venus838LPx miniature GPS module coupled to an ATMega32E5 microcontroller. The speech comes in the form of pre-recorded samples stored on an SD card. There is a small on-board amplifier to drive a single speaker. For extreme authenticity perhaps it could be attached to a GSM mobile phone module to provide a dial-up service, but he’s got everything he needs for a New Years Eve.

Want to hear what that that bit of nostalgia sounded like? Check out the quick clip below. As for modern replacements, we’ve had at least one talking clock here in the past, but not one using GPS.

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The SD-11 Sphericular Display: Pixels That Aren’t Pixels

January 21, 2018 by 32 Comments

Ever heard of a sphericular display? [AnubisTTP] laid hands on a (damaged) Burroughs SD-11 Sphericular Display and tore down the unusual device to see what was inside. It’s a type of projection display with an array of bulbs at the back and a slab of plastic at the front, and the rest is empty space. The usual expected lenses and slides are missing… or are they? It turns out that the thin display surface at the front of the unit is packed with a two- dimensional 30 x 30 array of small lenses, a shadow mask, and what can be thought of as a high-density pixel mask. The SD-11 was cemented together and clearly not intended to be disassembled, but [AnubisTTP] managed to cut things carefully apart in order to show exactly how these fascinating devices solved the problem of displaying digits 0-9 (with optional decimal points) on the single small screen without separate digit masks and lenses to bend the light paths around.

The “pixel mask” of the SD-11

The face of the display can be thought of as a 30×30 array of pixels, with each of the microlenses in the lens array acting as one of these pixels. But these pixels are not individually addressable, they light up only in fixed patterns determined by the “pixel mask”. How exactly does this happen? With each microlens in the array showing a miniature of the bulb pattern at the rear of the display, a fixed image pattern can be shown at the front by putting a mask over each lens: if a certain bulb at the rear needs to result in a lit pixel at the front, that mask has a hole in that bulb’s location. If not, there is no hole and the light is blocked. Just as the compound lens is a two-dimensional array of microlenses, so is the light mask really a two-dimensional array of smaller masks: exactly one per microlens. In this way the “pixel mask” is how each bulb at the rear results in a fixed pattern (digits, in this case) projected at the front.

The Burroughs SD-11 Sphericular Display was very light, containing mostly empty space where other projection displays had lenses and light masks. It turns out that the SD-11 operates using the same principles as other projection displays, but by using a high-density light mask and a compound lens array it does so by an entirely different method. It’s a great peek into one of the different and fascinating ways problems got solved before modern display solutions became common.