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 [davisr] has been hacking away at the platform. His latest work brings full-fat Linux to the fore.
The work builds upon [davisr]’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 [davisr]’s work is 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 [davisr]’s work goes next, 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.
We hadn’t considered how challenging it might be to try drawing long-term on a tablet, and it sounds as though Apple didn’t, either. According to [Eric Strebel], who normally designs products for other people, there are many problems to solve. The camera area creates a bump on an otherwise flat backside, so it wobbles on the table. It’s thick. It’s too easy to run your stylus off the side.
Yes there are tablet holders out there, even a few with cup holders, but almost none of them have a kickstand for holding the thing vertically. If you want something done right, you have to do it yourself. And so [Eric] designed his ideal stand to solve all of these problems (video, embedded below). It’s mostly made of laser-cut foam core board, with some layers of poster board added to make the bezel totally flush with the tablet.
[Eric] can snap the tablet in place and use it flat, or fold back the upper half into a stand. It even works well over on the couch, or sitting up in bed. We particularly like the window gasket feet and all the versions of his hinges, which start with strips of cheesecloth and end in grosgrain ribbon. [Eric]’s approach to design always reminds us to keep an open mind about materials and methods. If you try using what you already have, the results may surprise you. Check out the build video after the break.
In times like these, we all need to look beyond ourselves. This project might help: OnStep is an open-source telescope controller, a device that controls a telescope to point at something interesting in the sky. Want to take a look at M31? Use an app on a PC or smartphone, select the object and the OnStep will pan and tilt your telescope until the Andromeda Galaxy pops into view.
There’s been a marked trend towards modern tablets and phones having fewer expansion options. It’s becoming rarer to find a microSD slot available, which can be particularly frustrating. For [davisr], this simply wouldn’t do, and they set about hacking their ReMarkable tablet.
The ReMarkable already has a set of pads for an SDHC interface on the main board, ready to go. Despite this, both hardware and software modifications are required to get things up and running. [davisr] started by soldering some wires to the main board, feeding them to a microSD socket, which was mounted on the edge of the tablet in a convenient nook. The case was then delicately modified to make a slot for cards to be inserted and removed. With this done, the kernel was then recompiled to enable support for the SDHC interface, and everything was up and running.
Regardless of how you might feel about Apple and the ecosystem they’ve cultured over the years, you’ve got to give them some credit in the hardware department. Their “Retina” displays are a perfect example; when they brought the 2,048 by 1,536 panel to the iPad 3, the technology instantly became the envy of every tablet owner. But what if you want to use one of these gorgeous screens outside of Apple’s walled garden?
As it turns out, there are a number of options out there to use these screens on other devices, but [Arthur Jordan] wasn’t quite happy with any of them. So he did what any self respecting hacker would do, and built his own adapter for iPad 3 and 4 screens. Not that he did it completely in the dark; his design is based on the open source Adafruit Qualia driver, which in turn was based on research done by [Mike’s Mods]. A perfect example of the open source community at work.
The resulting board allows you to connect the Retina display from the iPad 3 or 4 to any device that features Embedded DisplayPort (eDP). Rather than put a dedicated port on his board, [Arthur] just left bare pads where you can solder up whatever interface method your particular gadget might use. In his case, he wanted to hook it up to an x86 UP Core SBC, so he even came up with a seperate adapter that breaks out that board’s diminutive display connector to something that can be soldered by hand.
So what’s different between the board [Arthur] developed and Adafruit’s Qualia? Primarily its been made smaller by deleting the DisplayPort connectors in favor of those bare pads, but he’s also dumped the backlight control hardware and 3.3V regulator that in his experience hasn’t been necessary with the eDP devices he’s worked with. So if space is a concern in your build, this version might be what you’re after.
Signing up for college classes can be intimidating, from tuition, textbook requirements, to finding an engaging professor. Imagine signing up online, but you cannot use your monitor. We wager that roughly ninety-nine percent of the hackers reading this article have it displayed on a tablet, phone, or computer monitor. Conversely, “Only one percent of published books is available in Braille,” according to [Kristina Tsvetanova] who has created a hybrid tablet computer with a Braille display next to a touch-screen tablet running Android. The tablet accepts voice commands for launching apps, a feature baked right into Android. The idea came to her after helping a blind classmate sign up for classes.
Details on the mechanism are not clear, but they are calling it smart liquid, so it may be safe to assume hydraulic valves control the raised dots, which they call “tixels”. A rendering of the tablet can be seen below the break. The ability to create a full page of braille cells suggest they have made the technology pretty compact. We have seen Braille written on PCBs, a refreshable display based on vibrator motors, and a nicely sized Braille keyboard that can fit on the back of a mobile phone.
With the incredibly low cost of software defined radio (SDR) hardware, and the often zero cost of related software, there’s never been a better time to get into the world of radio. If you’ve got $30 burning a hole in your pocket, you’re good to go. But as with any engrossing hobby that’s cheap to get into, you run the risk of going overboard eventually.
For example, if the radio gear inside your car approaches parity with the Kelly Blue Book value of said vehicle, you may have been bitten by the radio bug. In the video after the break, [Corrosive] gives us a tour of his antenna festooned Hyundai Accent, that features everything he needs to receive and analyze a multitude of analog and digital radio signals on the go.
He starts with the roof of the car, which is home to five whip antennas (not counting the one from the factory installed AM/FM radio) and two GPS receivers. The ones on the rear of the car feed down into the trunk, where a bank of Nooelec NESDR RTL-SDR receivers will live in a USB hub. He’s only got one installed for test purposes, but he’ll need more for everything he’s got planned. Also riding in the back is a BCD780XLT scanner, which he got cheap on eBay thanks to the fact it had a dead display.
Luckily, where [Corrosive] is going, he won’t need displays. The SDR receivers and the scanner are all controlled from the driver’s seat by way of a Windows 10 tablet. This runs the ProScan software that provides a virtual interface to the BCD780XLT, as well as various SDR interfaces. He’s also got Gpredict for tracking satellites and ADS-B programs like Virtual Radar.
The car’s head unit has been replaced by a rooted Android entertainment system which supports USB host mode. [Corrosive] says it isn’t hooked up yet, but in the future the head unit is going to get its own SDR receiver so he can run programs like RF Analyzer right in the dashboard. We’re willing to bet that this will be the only car in the world that has both a waterfall display and the “Check Engine” light on at the same time.