Using E-Paper Displays for an Electronic Etch A Sketch

Electronic things are often most successful when they duplicate some non-electronic thing. Most screens, then, are poor replacements for paper. Except, of course, for E-paper. These displays have high contrast even in sunlight and they hold their image even with no power. When [smbakeryt] was looking at his daughter’s Etch-a-Sketch, he decided duplicating its operation would be a great way to learn about these paper-like displays.

You can see a video of his results and his findings below. He bought several displays and shows them all, including some three-color units which add a single spot color. The one thing you’ll notice is the displays are slow which is probably why they haven’t taken over the world.

The displays connect to a Raspberry Pi and many of the displays are meant to mount directly to a Pi. The largest display is nearly six inches and some of the smaller displays are even flexible. It appears the three color displays were much slower than the ones that use two colors. To combat the slow update speeds, some of the displays can support partial refresh.

The drawing toy uses optical encoders connected to the Raspberry Pi. The Python code is available. Even if you don’t want to duplicate the toy, the comparison of the displays is worth watching. We were really hoping he’d included an accelerometer to erase it by shaking, but you’ll have to add that feature yourself. By the way, in the video, he mentions the real Etch-a-Sketch might work with magnets. It doesn’t. It is an aluminum powder that sticks to the plastic until a stylus rubs it off.

We’ve seen these displays many times before, of course. If you are patient enough, you can even use them as Linux displays.

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E-ink Typewriter Is Refreshingly Slow

It’s pretty hard to use the internet to complete a task without being frequently distracted. For better or worse, there are rabbit holes at every turn and whilst exploring them can be a delight, sometimes you just need to focus on a task at hand. The solution could be in the form of distraction-blocking software, razor-sharp willpower, or a beautifully crafted modern “typewriter”. The constraint and restriction of a traditional typewriter appealed to [NinjaTrappeur], but the inability to correct typos and share content online was a dealbreaker. A hybrid was the answer, with a mechanical keyboard commanding an E-ink display driven by a Raspberry Pi.

The main point of interest in this build is the E-ink screen. Though it’s easy to acquire theses displays in small sizes, obtaining a screen greater than four inches proved to be a challenge. Once acquired, driving the screen over SPI was easy, but the refresh rate was horrific. The display takes three seconds to redraw, and whilst [NinjaTrappeur] was hoping to implement a faster “partial refresh”, he was unable to read the appropriate values from the onboard flash to enable manual control of the drawing stages. Needless to say, [NinjaTrappeur] asks if people have had success driving these displays at a more usable rate, and would love to hear from you if so.

Some auxiliary hacks come in the form of terminal emulator adaptation, porting the E-ink screen library from C++ to C, and capturing the keyboard input. A handmade wooden case finishes it off.

If it’s old-school typewriters that float your boat, we’ve got you covered: this solenoid-actuated typewriter printer eventually became a musical instrument, and this daisy wheel machine produces ASCII art from a live camera.

[Via Boing Boing]

A Low Cost, Dead Tree Touch Screen

Remember the “paperless office”? Neither do we, because despite the hype of end-to-end digital documents, it never really happened. The workplace is still a death-trap for trees, and with good reason: paper is cheap, literally growing on trees, and it’s the quickest and easiest medium for universal communication and collaboration. Trouble is, once you’re done scribbling your notes on a legal pad or designing the Next Big Thing on a napkin, what do you do with it?

If you’re anything like us, the answer to that question is misplacing or destroying the paper before getting a chance to procrastinate transcribing it into some useful digital form. Wouldn’t paper that automatically digitizes what you draw or write on it be so much better? That’s where this low-cost touch-sensitive paper (PDF link) is headed, and it looks like it has a lot of promise. Carnegie-Mellon researchers [Chris Harrison] and [Yang Zhang] have come up with cheap and easy methods of applying conductive elements to sheets of ordinary paper, and importantly, the methods can scale well to the paper mill to take advantage of economies of scale at the point of production. Based on silk-screened conductive paints, the digitizer uses electrical field tomography to locate touches and quantify their pressure through a connected microcontroller. The video below shows a prototype in action.

Current cost is 30 cents a sheet, and if it can be made even cheaper, the potential applications range from interactive educational worksheets to IoT newspapers. And maybe if it gets really cheap, you can make a touch-sensitive paper airplane when you’re done with it.

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[Ben Krasnow] Hacks E-Paper For Fastest Refresh Rate

[Ben Krasnow] is known for his clear explanations alongside awesome hardware, being one of only a few hackers who owns an electron microscope. This time he’s explaining how E-paper works while modifying the firmware of a 4.2 inch E-paper module to get a higher refresh rate. As for the awesome hardware, he also analyses the signals going to the E-paper using an ultra-fancy loaner oscilloscope.

E-paper explanation diagram
E-paper explanation diagram

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.

Continue reading “[Ben Krasnow] Hacks E-Paper For Fastest Refresh Rate”

Breadboarding with E-Paper

[David Watts] picked up an inexpensive Waveshare e-Paper display. He made a video about using it with a breadboard, and you can see it below.

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.

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The Other Way to Brick a Mac Classic

Why would you build a mini Mac Classic using LEGO and a Raspberry Pi? Well, why wouldn’t you?

[Jannis Hermanns] couldn’t find a reason to control this outburst of nostalgia for the good old days of small, expensive computers and long hours spent clawing through the LEGO bin to find The Perfect Piece to finish a build. It turns out that the computer part of this replica was the easy part — it’s just an e-paper display driven by a Raspberry Pi Zero. Building the case was another matter, though.

After a parti-colored prototype with whatever bricks he had on hand, a session of LEGO Digital Designer led him to just the right combination of bricks to build an accurate case, almost. It turns out that the stock selection of bricks in LDD won’t allow for the proper proportions for the case, so he ordered the all-white bricks and busted out the Dremel. LEGO purists may want to avert their eyes from the ABS gore within, but in the end the case worked out and the whole build looks great.

Fancy a full-size Mac Classic reboot? How about this iPad docking station? Or if tiny and nostalgic is really your thing, this retro-future terminal build is pretty keen too.

[via r/raspberry_pi]

Hackaday Links: August 28, 2016

E-paper looks awesome, but it’s a pain to work with. You need only look at the homebrew implementations of e-paper drivers and the mess of SMD components for proof of that. [jarek] wanted to play around with e-paper and developed this tiny little driver for a Teensy. It’s a fun toy, and the simplest possible circuit necessary to drive this particular e-paper module.

I am once again asking if anyone knows where to buy this computer case. No, not a complete system – I just want the case, folding keyboard, and monitor integrated into an mATX enclosure.

Back in 1985, a young [Matthias Wandel] built a remote control forklift out of a few windshield wiper motors, wood, and not much else. He’s rebuilt this toy recently, just to prove you can build anything with a stack of plywood and a wood gear template generator.

More Adafruit muppets they probably can’t call muppets. Yaaay. This time it’s J is for Joule. Watts that? A second.

The Raspberry Pi Project, one of our favorite projects in the Hackaday Prize that uses a Raspberry Pi, one of the most liked, viewed, and followed projects on Hackaday.io, and a technological tour de force the likes of which have not been seen since the invention of the steam engine got an update this week. [Arsenijs] and the rest of the Raspberry Pi Project team have released a version of their Raspberry Pi pinout helper. Previously, this tool was only used internally to the project, but since this pinout helper has such far-reaching utility they’ve decided to release a public version. Truly, they are kings among men.

This is possibly the coolest use of stacked plywood I’ve ever seen. It’s a spiral staircase, with each step made of 12 layers of plywood. The ‘spine’ of this staircase is a 3″ sch 40 steel pipe, with a proper foundation. The layer of ply are adhered to the pipe with construction adhesive, and each layer of ply is glued together with wood glue. No, it’s not up to code yet, but it was cheaper to build than just buying a spiral staircase.

[Brek] wrote a graphics library for the ubiquitous 128×64 monochromatic LCDs. It’s written for PICs, but damned if we can’t find a link to the library itself. Hopefully [Brek] will jump in the comments below.

Those really, really cheap ESP8266 modules only have 512kB of Flash in them. Here’s how you upgrade those modules to 4MB. You can do it without a hot air gun, and all you need is a few cheap Flash chips.

Here’s a sound card for a Raspberry Pi. No, that’s not a completely dumb idea. This sound card uses quality op-amps, 24-bit ADCs and DACs, and has MIDI. If you’re experimenting with Pure Data or any other Linux audio toy, this could be a useful addition to your Pi stack.