A Deep Dive Into E-Ink Tag Hacking

Over the last decade or so, e-ink price tags have become more and more ubiquitous, and they’ve now reached the point where surplus devices can be found inexpensively on various websites. [Dmitry Grinberg] found a few of these at bargain-basement prices and decided to reverse engineer and hack them into monochrome digital picture frames.

Often, the most difficult thing about repurposing surplus hardware is the potential lack of documentation. In the two tags [Dmitry] hacked, not only are the labels not documented at all, one even has an almost-undocumented SoC controlling it. After some poking around and some guesswork, he was able to find connections for both a UART and an SWD debugging interface. Fortunately, the manufacturers left the firmware unprotected, so dumping it was trivial.

Even with the firmware dumped, code for controlling peripherals (especially wireless devices) is often inscrutable. [Dmitry] overcomes this with a technique he calls “Librarification” in which he turns the manufacturer’s firmware into libraries for his custom code. Once he was able to implement his custom firmware, [Dmitry] developed his own code to wirelessly download and display both gray-scale and two-color images.

Even if you’re not interested in hacking e-ink tags, this is an incredible walk-through of how to approach reverse-engineering an embedded or IoT device. By hacking two different tags with completely different designs, [Dmitry] shows how to get into these systems with intuition, guesswork, and some sheer persistence.

If you’d like to see some more of [Dmitry]’s excellent reverse-engineering work, take a look at his reverse-engineering and ROM dump of the PokeWalker. If you’re interested in seeing what else e-ink tags can be made to do, take a look at this weather station made from the same 7.4″ e-ink tag.

An E-Book Reader, But Just For Haiku

E-ink displays haven’t revolutionized the world so much as served us humbly in e-book readers such as the Kindle and its ilk. Most such readers are designed for extended sessions reading novels and the like, but [Roni Bandini] decided a haiku-sized device was in order. 

The diminutive device runs off an ESP32, which has plenty of clock cycles for easily driving displays. It’s paired with a 2.9 inch Waveshare e-ink display, upon which it delivers poetry in the popular Japanese haiku format – 5 syllables, 7 syllables, 5 syllables. Writing to the display is easy with the GxEPD library, which is compatible with a variety of common e-ink displays. Presently the poetry is hardcoded in the program, and there’s plenty that could be included with the ESP32’s roomy program storage. However, [Roni] notes it would be simple to have the reader pull poems from an SD card instead.

It’s a fun project, and a great way to get familiar with the basics of working with e-ink displays. We’d love to see a WiFi-enabled version that pulls down the hottest daily haikus fresh from the web, too. Funnily enough, our own archives only feature one other reference to the famous Japanese art, which has little to do with poetry. If you fancy changing that, make something relevant and drop us a line. Video after the break.

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Old Kindle Shows HDMI Video, Eventually

Even with the recent price reductions on stand-alone panels, picking up a used Kindle is still arguably the most cost effective way to get your hands on a large electronic paper display. Especially when you consider the Kindle includes a battery, case, and electronics to drive the display. Bending the Kindle software to your whims introduces its own unique challenges of course, but with a little tweaking, an old e-reader can live again as whatever you wish it to be.

Case in point, the OkMonitor project by [Brendan Sleight]. Using a somewhat dizzying combination of software and hardware, he’s figured out a way to turn an older Kindle Paperwhite into a plug-and-play HDMI monitor. Is it a great monitor? Far from it. As the name implies, the best you can hope to get from this solution is an OK monitor. But at least it’s something.

There’s quite a bit going on behind the scenes in OkMonitor, which [Brendan] describes through a slideshow on the project page. But the high-level idea is that a Raspberry Pi 4 with a simple USB HDMI capture device takes the video input and converts it on the fly to a scaled down Kindle-friendly format. The converted video is streamed over WiFi to the jailbroken Kindle with netcat, where it’s displayed by a native video player. In the video after the break you can see that the end result looks pretty impressive, even if there is a considerable delay involved.

Despite the demonstration [Brendan] has put together for OkMonitor, we can’t say we’d watch many films over this setup. But the fact that you can plug any HDMI device into the “base station” and have the video sent out to one or more Kindles is undeniably impressive. It’s definitely worth a close look, even if you just take some of the concepts of this project to get your own Kindle repurposing idea off the ground.

We’ve recently seen some promising progress made towards repurposing large e-paper price tags labels, but it’s hard to imagine such niche devices will ever become cheaper than second hand Kindles. With continued software development, these old e-readers are likely to remain quite popular among hackers.

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Solar Pi Zero E-Paper Photo Frame Waits For The Right Moment

One of the biggest advantages of electronic paper is that it doesn’t require a constant power source to display a static image. Depending on the application, this can lead to a massive energy savings compared to more traditional display technologies. Of course, the electronics that actually drive the display are another story entirely. You need to reduce the energy requirements of the whole system if you really want to stretch your battery life.

So when [Giacomo Miceli] wanted to put together this solar powered e-paper photo frame, he had to come up with some creative ways to curb the energy consumption of the Raspberry Pi Zero that runs the show. While the 10.3 inch 1872 × 1404 panel would only require the occasional burst of power to flick over to a new image, the Pi would be a constant drain on the internal battery pack. Considering he wanted the frame to recharge from ambient light with an array of small solar panels, that simply wouldn’t do.

The solution came in the form of a PiJuice HAT and some scripts that decide how often the Pi is to be powered on based on the current battery level. If there’s enough power, it might be every hour or so. But the lower the charge, the longer the delay. When the energy situation is particularly dire, the Pi might only be turned on every couple of days. With the Pi off and the e-paper not drawing any power, all of the energy produced by the solar panels can be devoted to recharging the frame’s 1,000 mAh battery.

When the Pi does get booted up, it quickly connects to a server to download a new image and update the display. After that, it ascertains the current battery level and determines how long the PiJuice should wait before turning it back on. After these tasks are complete, it will turn itself off until the next scheduled event. All told, [Giacomo] says the Pi is only up and running for about a minute each time the image is refreshed on the e-paper. He says the system has been running for six weeks now, with the battery level occasionally dipping down to 40% or so before it climbs back up.

Admittedly the energy consumption of the frame could be cut drastically by replacing the Raspberry Pi with a simple microcontroller, but we appreciate the creativity. Besides, the power and flexibility afforded by the Pi means this frame could be taught quite a few new tricks with some updated software.

A Free Software OS For The ReMarkable E-Paper Tablet

If you’re looking to rid your day to day life of dead trees, there’s a good chance you’ve already heard of the reMarkable tablet. The sleek device aims to replace the traditional notebook. To that end, remarkable was designed to mimic the feeling of writing on actual paper as closely as possible. But like so many modern gadgets, it’s unfortunately encumbered by proprietary code with a dash of vendor lock-in. Or at least, it was.

[Davis Remmel] has been hard at work porting Parabola, a completely free and open source GNU/Linux distribution, to the reMarkable. Developers will appreciate the opportunity to audit and modify the OS, but even from an end-user perspective, Parabola greatly opens up what you can do on the device. Before you were limited to a tablet UI and a select number of applications, but with this replacement OS installed, you’ll have a full-blown Linux desktop to play with.

You still won’t be watching videos or gaming on the reMarkable (though technically, you would be able to), but you could certainly use it to read and edit documents the original OS didn’t support. You could even use it for light software development. Since USB serial adapters are supported, microcontroller work isn’t out of the question either. All while reaping the considerable benefits of electronic paper.

The only downside is that the WiFi hardware is not currently supported as it requires proprietary firmware to operate. No word on whether or not [Davis] is willing to make some concession there for users who aren’t quite so strict about their software freedoms.

We’ve been waiting patiently for the electronic paper revolution to do more than replace paperbacks with Kindles, and devices like the reMarkable seem to be finally moving us in the right direction. Thankfully, projects that aim to bring free and open source software to these devices mean we won’t necessarily have to let Big Brother snoop through our files in the process.

Hackaday Podcast 073: Betrayal By Clipboard, Scratching 4K, Flaming Solder Joints, And Electric Paper

Hackaday editors Mike Szczys and Elliot Williams review a great week in the hacking world. There’s an incredible 4k projector build that started from a broken cellphone, a hand-cranked player (MIDI) piano, and a woeful story of clipboard vulnerabilities found in numerous browsers and browser-based apps. Plus you’ll love the field-ready solder splice that works like a strike-on box match (reminiscent of using thermite to weld railroad rail) and we spend some time marveling at the problem of finding power cuts on massive grid systems.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~65 MB)

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EPaper Tablet Gets Desktop Linux Install

ePaper is an interesting thing, providing a non-backlit viewing experience that is much more akin to reading a book than staring at a screen. The reMarkable tablet is a device designed around just such a display, and [Davis Remmel] has been hacking away at the platform. His latest work brings full-fat Linux to the fore.

The work builds upon [Davis]’s earlier work, installing a microSD slot in the tablet to make development easier. Getting Linux running required a custom kernel, but once sorted, working with the reMarkable is easy. apt is available for easy software installs, and the tablet is demonstrated using several different pieces of software, like mtPaint and Xournal.

The golden part of all this has been getting automated partial screen refreshes working. ePaper displays take a long time to refresh the whole screen. Being able to do faster partial writes makes for a much faster interface, which is evident when some of the drawing software is demonstrated. Even Doom runs, but remains largely unplayable, sadly – the ePaper is still a long way off hitting 25 fps.

We look forward to seeing where [Davis] takes this project, and how display performance improves with newer reMarkable tablets. With the reMarkable 2 out for pre-order, there could be a step change in display speed on the horizon. We’re betting that there’s big things to come yet for ePaper – 2020 may finally be its year.