[Scott] could have gone chaotic evil with this setup, but he didn’t. No one could actually get on the Internet through him. Inside the “hotspot” are a Wi-Fi adapter and a Pi Zero running a captive portal. It broadcasts the default ‘XFINITY’ and ‘xfinitywifi’ SSIDs, plus a bunch of other common network names. Whenever anyone tries to connect, or worse, their phone automatically connects, they’ll hear a sad tuba cadence. This comes courtesy of a multi-sound effects box that’s controlled by the Pi through a relay board.
Meanwhile, the mark’s device is redirected to an internally-hosted “xfinity” login page. Anyone who actually goes on to enter their login credentials is treated to a classic horror film scream sample while the evil hotspot quietly stores their name and password and displays them on an e-ink display for all to see — a walking e-ink wall of sheep. Check out the demo after the break.
After starting out with a demo of the firmware in action before and after his modification, he explains how the E-paper works. The display is made up of many isolated chambers, each containing charged particles in a liquid. For example, the positive particles might be black and the negative might be white. By putting an electric field across each chamber, the white particles would be attracted to one end while the black would be attracted to the other, which could be the end you’re looking at. He also explains how it’s possible to get a third color by using different sized particles along with some extra manipulation of the electric field. And he talks about the issue of burn-in and how to avoid it.
Having given us that background, he then walks us through some of the firmware and shows how he modified it to make it faster, namely by researching various datasheets and subsequently modifying some look-up-tables.
Turning back to the hardware, he shows how he scratches out some traces so that he can attach scope probes. This alone seems like a notable achievement, though he points out that the conductive layer holds up well to his scratching. At that point he analyses the signals while running some demos.
The result is the very informative, interesting and entertaining video which you can watch below.
For our Northern Hemisphere readers the chill winds of winter are fast approaching, so it seems appropriate to feature a weather station project. Enjoy your summer, Southern readers!
[Fandonov] has created a weather station project with an Arduino Uno at its heart and a Waveshare e-ink display as its face to the world, and as its write-up (PDF) describes, it provides an insight into both some of the quirks of these displays, and into weather forecasting algorithms.
The hardware follows a straightforward formula, aside from Arduino and display it boasts an Adafruit sensor board and a hardware clock. Software-wise though there are some tricks to give the display a scalable font that other tinkerers might find useful, drawing characters as a matrix of filled circle primitives.
The write-up gives an introduction to forecasting based only on local readings rather than on the huge volumes of data over a wide area used by professional meteorologists. In play here is the Zambretti algorithm, which takes the readings and information about whether they are rising or falling, and returns a forecast from a look-up table.
As we’ll all be aware, even professional weather forecasting is fraught with inaccuracies, but this is nonetheless an interesting project that is very much worth a second look. Meanwhile we’ve covered huge numbers of weather stations in the past, a couple of interesting ones are this one using a classic TI99/4A home computer, and more relevant here, this one using an e-paper badge.
The E-Paper or E-Ink displays have several advantages. They are low power, they retain their display even without power, and they are very visible in direct light. The downside is they don’t update as fast as some other display technologies.
E-ink displays are becoming almost common in DIY electronics circles, and now we have very capable, low-power microcontrollers, some of which feature some sort of wireless connectivity. Combine these two, and you have the potential for a basic information screen — a low-power device that always displays some sort of relevant information, whether it’s the date or the weather.
For their Hackaday Prize entry, [Wenting] and [Dong] are building an e-ink calendar. It’s a calendar, it displays bitmaps, it can display the time, and with a little more hacking it can display the weather, current traffic, or train schedule. If this were the 90s, we would have called this an information appliance, and it would have blown everyone’s minds.
The current design of this e-ink calendar uses an 800 x 600 pixel display working in 16-level grayscale mode. The processor is an STM32F4, and in a cost-reducing revision, an external SRAM was thrown out and the frame buffer was moved to the internal RAM. The e-ink display is actually pretty quick, allowing for greater than 10 FPS in 1-bit mode.
As with any e-ink project, driving the display is a minor nightmare, but [Wenting] is able to push a few frames per second to the display. That’s good enough for a device that shouldn’t actually change all that much — this is a calendar, after all.
[Nick Ames]’s Flexible Smartwatch project aims to create an Open Source smartwatch made out of a flexible, capacitive e-ink touchscreen that uses the whole surface of the band. This wraparound smartwatch displays information from the on-board pulse and blood oximetry sensor as well as the accelerometer and magnetometer, giving you a clear idea of how stressed you are about your upcoming meeting.
The display [Nick] went with is called an electrophoretic display (EPD). It’s 400×200-pixels at 115ppi with a 4″ diagonal, and can bend around a wrist. It can draw shapes in 16 shades of gray with a refresh time of under a second or B&W with a faster refresh.
The smartwatch described in [Nick]’s project would be 2.5mm thick — certainly thin enough to fit under a sleeve. We suspect that success of the form factor may hinge on [Nick]’s success in making it not look like a hospital wristband. Although this gives us the thought that a biofeedback-sensing smart wristband is probably the future of hospital stays.
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.