If you haven’t kept up with the world of e-ink displays, here’s some good news: they are pretty cheap now. For as little as $15 you can get a small e-ink display that has good enough performance and contrast to actually do something useful. There’s only one problem: figuring out how to drive them in your project.
Tired of seeing nothing but wiring diagrams and sample code when it came to actually putting these e-ink modules to use, [Jouko Strömmer] decided to try his hand at creating a turn-key application for these gorgeous little displays. The result is PaperTTY, a Python program that allows the user to open up a fully functional Linux virtual terminal on an e-ink display.
Of course, there are some caveats. For one, this all assumes you’re using a Waveshare display (specifically their 2.13 inch HAT) connected to a Raspberry Pi over SPI. Not to say that’s the only hardware combination that will work, but it’s the only one that [Jouko] has done any testing on at this point. If you want to try to shake things up in terms of hardware, you might need to get your hands dirty.
The advantage of being able to open a Linux VT on one of these e-ink displays is pretty simple: you can run basically any piece of software you want on it. Rather than having to come up with software that specifically features support for the display, you can just use (or write) standard Linux console programs. [Jouko] mentions a number of popular programs such as vim and irssi, but you could just as easily write a Bash script to dump whatever data you like to the screen.
In the video after the break [Jouko] shows PaperTTY in action for the doubters who think these sorts of displays are no good for interactive use. The display is very crisp and readable, with no signs of flickering. Overall he says the experience is not unlike using a slow SSH connection. It might not be how we’d like to use a computer full time, but we can definitely see the potential.
You’ve probably noticed that the hacker world is somewhat enamored with overly complex electronic event badges. Somewhere along the line, we went from using a piece of laminated paper on a lanyard to custom designed gadgets that pack in enough hardware that they could have passed for PDAs not that long ago. But what if there was a way to combine this love for weighing down one’s neck with silicon jewelry and the old school “Hello my name is…” stickers?
[Squaro Engineering] might have the solution with Badgy, their multi-function e-ink name…well, badge. Compatible with the Arduino SDK, it can serve as anything from a weather display to a remote for your smart home. Oh, and we suppose in an absolute emergency it could be used to avoid having to awkwardly introduce yourself to strangers.
Powered by an ESP-12F, Badgy features a 2.9″ 296×128 E-Ink display and a five-way tactical switch for user input. The default firmware includes support for WiFiManager and OTA updates to make uploading your own binaries as easy as possible, and a number of example Sketches are provided to show you the ropes. Powered by a LIR2450 3.6 V lithium-ion rechargeable coin cell, it can run for up to 35 days in deep sleep or around 5 hours of heavy usage.
Back in 2016, Chinese company Dasung blew past their Indiegogo goal to fund the Paperlike: the world’s first general purpose E-Ink display. Rather than being stuck in a reader from your favorite purveyor of DRM like previous displays, the Paperlike could be used with whatever device you wanted; albeit in black and white and at a relatively low refresh rate. It promised to allow reading and writing on your computer or tablet without needing a backlight. The price was steep at $800 USD for a 13″ display, but clearly enough people were interested to make the device a reality.
You can count [Kev Zettler] among the Paperlike devotees. He’s such a fan of the technology that he’s on the road to building a DIY E-Ink laptop using the latest generation Paperlike Pro. But before he can do that, he’s got to take the thing apart and see how it ticks. While a lot of the proprietary magic that makes the display work is still a mystery, he does his best to document the internals for those of us who are a bit to shy to take a screwdriver to a display that costs $1,000.
It looks like the Paperlike Pro is designed (either intentionally or otherwise) to look a bit like the Amazon Kindle, and the construction method is unfortunately the same. The front panel is glued on, and needs to be peeled off by getting under it with something sharp and prying it off carefully. For a $100 e-reader we can deal with that, but for as much as the Paperlike Pro costs that kind of disassembly gives us the chills.
He’s identified the bare display module as a 13.3 inch ED133UT2, which led him down an interesting path investigating other displays in the same family. It turns out the one Dasung went with is essentially the low end of the spectrum. The display has glare issues and is permanently bonded to a piece of glass, whereas other models in the same family boast not only flexibility but anti-glare coatings. There’s even one with integrated touch screen. [Kev] mentions that one of those displays would be much better for his E-Ink laptop project, but we’re assuming he’s not going to toss this thing in the bin just because there’s better options out there.
Beyond the display itself there’s a custom Dasung control board that [Kev] says is a bit too complex for him to decipher, made especially difficult thanks to the fact that the chips have had their labels removed. One interesting discovery though was the USB port which is officially supposed to be just for power has all four wires connected to the main board, raising the possibility of some future software hacking.
[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.