We should all be familiar with QR codes, those blocky printed patterns containing encoded text, URLs, or other data. A few years ago they were subject to their own cloud of hype, but now they have settled down in their niche of providing a handy route for a smartphone owner to reach a website without having to type an address.
Have you ever wondered how they work? There are plenty of dry technical guides out there, but if they’re not your thing you might find [Nayuki]’s step-by-step guide to be of interest. It explains the encoding and error checking bit generation process before starting on the familiar three-squares pattern and timing bars of the QR code itself. The really interesting part comes with its explanation of overlays, a set of repeating patterns that are added to the final data segment, and how the pattern used is chosen to minimise penalties due to large blocks of the same colour in the final piece. The chances are most of us will never have to create a QR code from scratch, but it is this type of fascinating technical general knowledge that makes guides like this such an interesting read.
QR codes have appeared in quite a few projects here over the years, but the one we find particularly amusing is this project to hack them by changing one QR into another.
Via Hacker News.
It’s been a long time since we’ve logged into a UNIX mainframe (other than our laptop) but one of our fond memories is the daily fortune: small, quirky, sometimes cryptic sayings that would pop up on the login screen if your system administrator had any sense of humor.
Apparently, we’re not alone. [Alastair] made his own fortune clock which gives you a new “fortune” every second instead of every login. There’s a catch, of course. It’s a QR clock — the fortune is encoded in a QR code instead of being displayed in human-readable form. You have to take a picture of the tiny OLED screen to know what it says. (Watch it sending him Shakespeare sonnets in the video below.)
You probably know QR codes are good for conveying URLs, but their use as general-purpose text containers is underappreciated in our book, so we’re glad to see this example. Now, we’ve seen QR clocks before (here, and here), and this version does have the disadvantage that you can actually tell what time it is. But we’re grateful for the trip down memory lane.
Continue reading “E Pluribus Unix, QR-Style”
The clock is a perfect technology. For just a few dollars, you can buy a digital wristwatch and chronometer able to keep extremely accurate time for years without winding a spring or replacing a battery. Anything ‘improvement’ on the design of a clock only makes it harder to read, a feature exploited by the very 1337 binary clocks we see from time to time. [Ch00f] decided it was time to give way to the march of progress and build a completely unreadable clock. He came up with a QR code clock that is unreadable by humans and cellphones alike.
The hardware is built around nine 8×8 LED matrix panels resulting in a 24 x 24 pixel display, perfect for displaying a 21 pixel square QR code. The LED drivers are a standard multiplexed affair, but this project really shines in the firmware department.
The microcontroller [Ch00f] used – an ATMega328 – is far too small to store the 1440 QR codes for every minute of the day. No, this project would have to dynamically generate QR codes on the fly, not exactly an easy problem.
After looking over the official QR code standard, [Ch00f] wrote a rather large program that turns alphanumeric sequences into QR code. This runs on the microcontroller every minute, generating a new QR code for every minute of the day.
It’s nigh impossible for a human to read a QR code, but [Ch00f] figured he could make his project even less useful. By multiplexing the LEDs at a very low duty cycle [Ch00f] made it impossible for a camera to capture the entire QR code, even though the pattern of pixels is still visible to the human eye. A fabulously useless build that really steps up the game for unreadable clocks.
Video after the break.
Continue reading “QR clock is unreadable by humans and computers alike”
RFID seems to have invaded every part of our lives. Sure, the technology has been primarily used in government and industry, but that doesn’t mean that it doesn’t have consumer applications. Recently, we posted about [max’s] RFID dorm room lock, that he built to provide a safe, convenient way to access his room. A while back, we talked about an RFID spatially aware address book that used a combination of rfid tags and post-it notes to control the NFC enabled Nokia 3220 cell phone. Both of these projects highlight unique applications where RFID is used. We bash on RFID from time to time, mostly due to its security (or lack there of). That said, there is an interesting consumer solution out there for people who want to voluntarily use RFID called Touchatag (formerly known as Tikitag). The cool thing about Touchatag is that it uses a combination of RFID and QR (2-D barcode) tags to trigger applications on the Touchatag website. The starter kit, which includes 10 tags and a USB RFID reader, goes for about $40; a decent price considering the hacking potential for the RFID reader. In addition to using the reader, you can also use any NFC enabled phone to read the tags. While NFC enabled phones are currently few and far between, the technology will likely be implemented in many of the new phones released in the coming year.
We’re curious, what do you think is next for consumer RFID? What kind of innovative project ideas do you have?