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E-Ink Magic Calendar that runs off a battery powered Raspberry Pi (github.com/speedyg0nz)
685 points by edward 3 months ago | hide | past | favorite | 165 comments

Can’t explain why but all these E-Ink projects are so awesome and attractive to me. I’m surprised I can’t just buy a bunch of E-Ink style gizmos from some company to decorate my home and office. My wallet would be wide open to it constantly.

Great work and congrats on this!

These projects have a pleasant "lo-fi zen" aspect that makes them attractive, I think. They are simple, provide value yet fade into the background without sucking your attention like some other gadgets.

It’s because it’s not lit. It looks natural, and unobtrusive.

I’d love to have this, art, and other “appliances” and slabs with eink. Ex. My todo list. My email etc.

I think they capture the feel of the black-and-white LCD digital watch world from before color display android everything ubiquity.

Probably that's why you can't make money on it at scale that you can with any addictive type of device and so it's not attractive for most entrepreneurs - a lot of work to put in and not enough money to even buy a Cessna.

I’m trying to make it work as a product. I tend agree it’s a super niche market though.


You should take a picture with better lighting. Really makes your product look bad on first impression.

Target the high-end? There might be a demand for a device with an e-ink esthetic which takes care of, I don't know, planning the days of rich people? An actual need instead of a manufactured want? Or maybe the lower power consumption of an e-ink display can make it useful in other areas not yet identified instead of consumer products?

I buy old kindles for this, ~50$ per piece. they have a linux os & battery included. you get in through a serial port and a password generated for your serial number. downside is that you fight the kindle os in certain aspects.

see for example: https://github.com/Neelakurinji123/kindle-weather-display

I wonder what it would take to build your own firmware image if you were reusing for exclusive alternative use? Presumably there is a Linux kernel tree somewhere and you could pull the waveforms from the Amazon image?

Check out http://fread.ink/

Tried that, but when I was at the process of soldering the cables to the debug ports, the "solder spots" came out of the board :(

Now I need to press hard with a needles to make the serial port work - so it is quite hard to setup - at least until I install sshd there and setup wifi to make it work wirelessly.

Do you have a list of compatible kindle models, and how to identify them?

I use most the paperwhite 2nd generation (212ppi resolution) as this had good availability and price. but the devices are quite hard to keep apart

the mobileread forum ist full of good information e.g.: https://www.mobileread.com/forums/showthread.php?t=267541

Check out the Inkplate - a great e-ink platform for all these projects and more:


Here's code that works with inkplate from a previous hn post :)


Rahul got oauth2 flows working to get google calendar access.

Google Calendar provides a calendar URL which might be more convenient.

Used it in this thing: https://github.com/lawik/calendar_gadget

i bought the 6" display from eink.com to build a small personal art project - an infinite scrolling procedurally generated landscape based on this project - https://github.com/LingDong-/shan-shui-inf

A few gotchas:

1. some of these eink boards are hard to procure as a consumer. the vendors want you to be a company

2. the driver boards are purchased separately, are definitely required, and sometimes have windows software (vs easy to use rasp-pi drivers)

3. support is often difficult or from the OEM so english-language communication can be difficult.

I had the same idea a few weeks back. Until i tried it. the javascript there is VERY slow. on an overclocked r-pi zero in chrome it takes > 5 minutes to render one. A few min of r-pi 0 time (1.9W) will kill batteries fast...

This is very interesting. Do you have a write up on the procedurally generated landscape part?

It was posted recently, so there's some discussion here[1]

1: https://news.ycombinator.com/item?id=23469233

A Raspberry Pi Zero and Pimoroni's Inky Impression are a very easy cheap setup to have a cute eink gizmo. Here's a twitter thread I posted with some images of it working: https://twitter.com/berenguel/status/1344016064196304899 and links to the screen as well.

I’m sorry to have to let you know your wallet may empty if you have not seen this already:

[edit: 4.7” ESP32 based epaper display with touchscreen, built in battery and expansion ports]


I scoured the wave share site for all the other e-ink screens and there're many cheaper ones.

You can get small e-ink screens (without a HAT, requires adapter ~10$ and dev board which is necessary anyway) for much cheaper.

5.8 inch is 40$

800×480, 7.5inch 50$

400x300, 4.2inch E-Ink raw display, three-color 26$

The cheaper ones are cheap because:

1) Each size comes in a low res and a high res variant, the low res ones are a lot cheaper

2) No HAT, so no built-in dev board for the PI. You do need to somehow connect it to your dev board. An adapter with SPI costs 10$, a dev board with esp8266 that has built-in adapter costs ~18$. Both are officially from wave share available on their site as well

3) All boards below 7 inch are relatively affordable. After that the price increases are huge

4) Not sure why, but price difference between black/white and 3-color is negligible. So feel free to pick a 5 inch tricolor screen for like 40$!

re: #4

Watch out for a few things:

1. Refreshes are much slower on 3-color eInk panels than on monochrome ones (eg: 20 sec vs 2)

2. Partial refresh on 3-color panels is rare and quickly gets messy around the edges. Partial refresh on monochrome panels is a relatively simple thing to do.

3. Greyscale on a 3-color eInk screen is VERY VERY VERY hard! Officially it is not supported at all. By any 3-color panel. I made it work [1] but even then, it is very very slow (bordering on a full minute per refresh).

4. Stock waveforms are rarely good. And almost no vendor will give you proper temp-compensated partial update waveforms. Developing your own waveforms for monochrome panels is easy and simple (~day). Developing your own waveforms for 3-color panels is a lot of work (~weeks + more weeks once you need to support more than just "21-25 celsius")

[1] http://dmitry.gr/?r=05.Projects&proj=29.%20eInk%20Price%20Ta...

I’m waiting on the dev board they sell on waveshare. Definitely affordable under $20.

For this type of project the esp32 seems like the better choice than the pi zero.

There’s also the RP2040 if you want work in the pi ecosystem. Arduino and u-blox have those with wifi I think

This is incredible for something I have in mind. Going to do a bit more reading, but the price and size are ideal for my use case.

I think I know why these look so attractive:

e-ink is the perfect blend between technology (screen can display whatever you want) and the analogue/physical world (it looks like a piece of paper which you can put in a wooden frame and interact with).

Another example for me is the “Buddha Machine” by FM3 (https://www.fm3buddhamachine.com): it’s basically a box that plays some ambient loops (technology) but it looks like a small and unthreatening transistor radio with nice tactile buttons (physical).

This desktop dashboard with three analog panel meters is gorgeous:

Ambient Executive Dashboard | Uncrate https://uncrate.com/ambient-executive-dashboard/

A new version that uses WiFi instead of a defunct paging network would be nice.

Plans to mod original ones so the meters could be driven by a micro-controller or Raspberry Pi would be cool.

Here's one for $125 that I'd been planning on buying.


The project, found on hn: https://rahulrav.com/blog/e_ink_dashboard.html

Agreed. I’m surprised the NYT won’t sell me an official version of this: https://news.ycombinator.com/item?id=25063726

They are neat. It's not as much in your face as a normal display plus they require almost no power so you can do awesome things with a SBC or an Arduino, smb32 or something else if you really want to make something completely off the grid. The Denali is that eink displays are still insanely expensive compared to any other screen.

At the same time, disapointed reminder of the lack of the progress on cheap large eink displays.

For me it’s a cost issue, this is over $200… I might pay $100 for it, but this wouldn’t be a must-buy for me until it hits ~$50

This one might be cheaper: https://github.com/zephray/NekoCal

...from the same guy who did this: https://news.ycombinator.com/item?id=16140284

I've been using another eink project dashboard, which cost me less as the screen is a smaller one, but it doesn't have colour: https://github.com/mendhak/waveshare-epaper-display

The main problem with e-ink is finding a display that doesn't cost 5x what an LCD of the same size would cost. This display was $179 before it became unavailable. That's on the low end for such displays bigger than phone-sized.

If the e-ink people ever overcome their cost problem, we'll see many more products.

Just curious but is it the lack of mass production or something sinister like patents / monopoly?

Patents & monopoly

Apparently, this is not true according to an HN user robinsoh who works in the industry. Check his comment history more info:


He doesn't seem to ever provide any evidence for his claims other than a repeated "I work in the display industry"..

I think you've misunderstood my comments.

I saw this recurring theme on HN that electrophoretic panels were expensive due to patents and evil misdeeds by that most evil corporation called E-Corp.

I thought, hey, I work in this bloody display industry myself where everything is about volume, volume and more volume, and I hangout with their guys at conferences and events, and I've never heard such a thing as them using patents to attack other industry players. Are they really attacking people and hurting customers that want to use their technology as alleged?

So I asked a simple question each time I saw that claim that E Ink uses patents to attack startups or similar claims. What's the evidence?

And guess what. Now it turns back to people like you who ask what is my evidence that there's no evil misdeeds. And to which I just feign shock, oh no, it must be true then, since a lack of evidence for them being innocent of the alllegations must mean they are guilty.

So we're left back at square 1. I hope people with a smarter mind than mine can arrive at whatever the correct conclusions are.

Could you please tell a bit more about the volume-side of story? Somehow I feel that E-ink is at this weird point on the cost/volume curve because it is a fundamentally flawed display technology: monochrome or a couple of dull colors at best, very slow refresh rate (with ghosting/leftover on partial refresh).

LCD/OLED displays were also very expensive initially, but because they're so much appealing universally, loads of money got poured into the industry to make them better and cheaper (mostly due to volume demand).

There's no such amount of money/interest in making E-ink better and cheaper :(

Please search my comment history for what I posted about electrophoresis and physics. I don't think they'll be able to get past the physical limitation. To summarize, you either move ink fast but end up losing bistability, or move ink slow, as it is currently. Most people don't realize electrophoresis has remained at about 700ms for an update over the last decade. Tricks like A2 sure with the Dasung, but nothing substantial.

As for the comment about "money/interest", see my comments about why a venture capitalist would have little interest in spending billions trying to create new display tech and fighting hard expensive physics problems when they could get higher rate of return by investing in another software service or ML/AI company. That said, Jeff Bezos spent hundred million or more on trying to get Liquavista working, Qualcomm spent lord knows how much on Mirasol. Great demos, but just couldn't get the process scaled or reliable enough to commercialize. Physics is hard. Physics is expensive.

Thanks a lot!

VC money is unlikely the source for this kinda of industrial research and bumpy road to scalability.

LCD/OLED panels got so cheap largely due to Korean/Japanese/Chinese government subsides. I doubt any of them will do so for e-ink.


Seems to be a meaty thread if anyone else is curious.

I mean, as long as they have patents they don’t need to “attack” others. A patent is enough on its own to prevent others from innovating. That’s the function of a patent after all!

At least this [1] article seems to indicate the presence of patents

[1] https://www.businesswire.com/news/home/20171220005895/en/E-I...

I asked someone from Visionect (eInk maker) what was driving the price for large panels and they said the same thing: just not enough volume yet.

Well, to be fair, large displays tend to be fragile and unwieldy as well. Depends a lot on manufacturer, but in essence short production runs also don’t help lower the price.

The project uses tri-color e-ink display. You can downgrade to two colors (and use e.g. dithering to get shades of gray) and get almost the same functionality for less money.

Huh, I see non tri-color version is still available in my country (Poland): https://kamami.pl/en/displays-for-raspberry-pi/577635-1248in... but forget the "less money" part...

This project is really cool, but I would prefer to have "a new picture every morning" in a frame than a calendar. For my purposes the e-ink displays are still a bit too small....

I just used an old eBook reader I had lying around. It shows the weather forecast.

Did you repurpose the screen or use the e-reader software to point to a data source?

I used a kit to ‘root’ it and allow installing software. I then installed some handy utility which basically just shows a web page and refreshes it every so often.

I just made a simple weather web app which connects to a free service. This works great. I could have written a little Android app to do the same, but my memory of Android UI is that I never ‘got’ it so this seemed easier.

Is there any kind of projector display might would work for this?

Sure but e-ink is nice as it doesn’t emit light.

Hey man, this is so cool.

I hope it’s okay to plug here: I am working towards releasing a similar product for sale:


Unfortunately the display isn’t as big as the one you chose and it isn’t battery powered. But I am starting to ship the first units, so there is that :)

Completely off topic, but you could have followed "Breakfast at Tiffany's" with "Dinner with Andre"!


You weren't lying about being completely off topic.

That's cool. Why not battery powered though? That seems like one of the biggest benefits of e-ink and also a wire coming out of your calendar seems like a pretty huge drawback.

Love the wood bezel though; looks really nice.

If I make it battery powered it needs to run on a charge for a few months, otherwise it becomes a hassle. And then, it must be possible to charge it easily.

Also, space. Right now the calendar is 7mm think and I think it won’t look as nice on the wall if I make it much thicker.

There are a lot of edge cases to consider. It’s definitely on my wish list but I cut it out for simplicity, for now.

This looks great! Two questions if i may:

1. Any plans to release some general purpose version of this? Ie i'd love to buy this and hook it up to an HTML webpage i generate or something. Then it's flexible to whatever i want to show on my dashboard.

2. Any plans for how consumers should power this hanging on a wall? Since it's wired it looks like.

re 1:

In principle that’s something that I could enable eventually. It’s a nice idea. I’ll think about it.

re 2: There is a standard usb plug at the far end of the cable. It can be plugged into a usb charger.

Looks fantastic, good luck with it :)

Heh that's cool. It renders the calendar as HTML and then uses selenium to open up headless chrome and screenshot it and then send the bitmap to the eink display. Clever.

I use Python Imaging Library + Seaborn to push out a bar chart bitmap representing some PiHole statistics to this: https://thepihut.com/products/inky-impression-7-colour-epape...

Ah nice. Yeah I'm looking for the right display for my skymap that shows the sun and moon and planets as they track across the sky. It's fun to see the sun curve change with the seasons. Would be way better to have on 7 color eink in the living room than on my phone or laptop.

This one looks good. Are there any that are like 3 inches bigger with borderline similar price points?

there has to be a simpler way to draw a grid. there has to.

Simpler in runtime overhead. Simpler for a developer familiar with the tools used here, but less so with others? Maybe not.

This seems to be a hobbyist project, not a major corporate effort where $100Ks were spent on tech selection.

I would not be surprised if a corporation would spend $100Ks on tech selection and end up with a headless Chrome too.

All the complexity is handled by well known tools/libraries.

I can code a selenium script to capture a screenshot in my sleep.

Often using tools your know is the best solution.

Your free to fork this and come up with a cleaner implementation. This is probably why you need a PI Zero. Smaller micro controllers can't run a full browser.

Most of these projects are just whatever can be hacked together in a weekend.

PostScript, maybe.

Instead of generating HTML from calendar data, generate PS and have Ghostscript convert it to PNG.

I don't know PostScript, and based on the example code in the wikipedia article (https://en.wikipedia.org/wiki/PostScript#The_language), I was able to get it to draw some text in a few minutes.

When all you have is a hammer...

I would volunteer LaTeX but that's also 100s of MBs/GBs of dependencies to be fair. Perhaps an SVG rasterizer would suffice here.

Sure. But this approach sounds like a sensible base to quickly whip up all sorts of little projects.

That is not clever. That is horrifying.

You have just massively bloated your set of dependencies to accomplish something you could have done with a rudimentary GUI toolkit.

Why tough? It works. What exactly is wasted here? 100MB for Chrome binary and that few percent of CPU hike while rendering the image? Is it worth wasting endless hours of time researching some niche, quirky, badly documented drawing library, where the hard earned end result has absolutely negligible difference from a human standpoint? Machines work for us, not reverse.

clever and horrifying are not mutually exclusive

he solved the problem with the tools he had, without spending time learning an alternative graphics layout system. I’m curious what you’d recommend as rudimentary tho, I would love to see such projects on lower power devices, but if you already need the Pi to talk to the ePaper, I don’t see the harm in burning a few cycles rendering a webpage to get the result you want.

“Premature optimization is the root of all evil”—Donald Knuth.

That phrase is so overused in light of massively over engineered solutions that are created every day in our industry . Let’s face it: this project loads some data via http and displays some text and primitives on a display. This can easily be handled on a esp32 with room to spare. But somehow we think it’s normal to involve an OS, a fully fledged computer and a browser to do this. Seriously, we need the opposite of the Knuth quote: “When in doubt don’t ship a browser” or something like that.

I wonder what the reason is for this solution. He must have one.

His GitHub says this: "This might sound like a convoluted way to generate the calendar, but I'm doing so mainly because (i) it's easier to format the calendar exactly the way I want it using HTML/CSS, and (ii) I can better delink the generation of the calendar and refreshing of the eInk display. In the future, I might choose to generate the calendar on a separate RPi device, while using a ESP32 or PiZero purely to just retrieve the image from a file host and update the screen."


Its easy to design something nice looking in html and css and compute is cheap. Seems like a fine solution to me. Maybe even better since you can push the image generation somewhere else and just have the RPI update the screen with an image which would save lots of power.

I've tried making nice interfaces with GUI toolkits and its a nightmare.

He has a valid point, generating the image on a separate device (heck, you could do that on AWS Lambda for free) and only grabbing the resulting image could vastly improve battery life. Then you could also switch from a power hungry Pi to a simpler choice like an ESP32.

Cause EInk display code works nice to just ship it an image type file. So, it's gotta be rasterized before, using Chromium makes that super easy - rather than hand crafting PNG.

I personally make SVG then rasterize but this isn't that terrible.

I was going down this route once, trying to use Inkscape headless. Is there a SVG-2-bitmap tool you can recommend?

Imagemagick. Does everything.

Somehow I missed that ImageMagick reads SVG, that is a much shorter dependency stack than selenium! Thanks

People gluing together lots of stuff to making something barely-working and massively inefficient is not a new phenomenon. Unfortunately, all the "maker movement" seems to have done is encourage it more. Careful design, knowledge and learning is being discouraged in favour of superficial understanding, copy-pasting, tweaking-until-it-works. They don't want to spend the time to learn the basics. I was recently saddened to see someone who had published code for a tiny project in Asm being asked if there could be "an Arduino version".

Some related philosophical discussions on that here: https://news.ycombinator.com/item?id=8679471

> Careful design, knowledge and learning is being discouraged in favour of superficial understanding, copy-pasting, tweaking-until-it-works.

This is like poo-pooing amatuer woodworking and saying “people should really become an apprentice first” - no one who has the education to do careful engineering is being discouraged, the field of hardware and software is now within reach of people who just wouldn’t take on any of these projects 10 years ago.

no one who has the education to do careful engineering is being discouraged

They are, because they think this stuff is just as good --- and it clogs the search results for those who do want to dig deeper. I often have to add "-Arduino -Maker" and a bunch of other filters to my search results to find the actually useful stuff.

This stuff IS good! It inspires people to task themselves with projects they don’t yet know how to do, and blog about what error codes they received and what they did to fix it.

Besides, how can you look down on them when you’re googling for answers instead of, you know, RTFM / getting your engineering degree?

and blog about what error codes they received and what they did to fix it

That is often more than useless to everyone not exactly in that one person's situation.

Besides, how can you look down on them when you’re googling for answers instead of, you know, RTFM / getting your engineering degree?

When trying to find TFM is itself a problem... I'm definitely not one to want to be "censoring misinformation" unlike a lot of others, but the blind leading the blind is certainly happening a lot and it doesn't help anyone.

This write-up itself appears to be of amazingly high-quality. What an incredible thing to give away to the world.

i’ve thought about this a lot because i use a whiteboard on my fridge. i would do this if it was huge like my whiteboard. like 2ft by 3ft. then i can read each day at a glance. seeing the whole month is huge. and writing on it means it should be a touch screen

i find myself wanting larger displays than is for sale a lot. i want an electric photo frame but not some 12in screen. i have great photos i want to see them 4ft tall. this is an underserved market

There are 31" and 42" e-ink displays available, but they cost a few thousand dollars. The 42" is pretty close to 2ft by 3ft, 25" x 33".

>There are 31" and 42" e-ink displays available, but they cost a few thousand dollars. The 42" is pretty close to 2ft by 3ft, 25" x 33".

I must have 4 or 5 old Kindles in a drawer by now, somehow. I wonder if you could hack together a grid of old Kindles to make a giant e-ink screen?

A lot of these kinds of projects render out an image and send that to the display. If you did it on a server, cut up the images, and had each kindle pull their image it should be pretty trivial. The only immediate issue that comes to mind is making sure they're relatively in sync when pulling a new image if you're worried about polling too often.

With 5 kindles you get a monday to friday one for each day for starters

Might be cheaper to put a printer on top of your fridge and automatically print calendar every morning into a plexiglass holder :-)

Hundred dollars for the printer, probably 20 cents a day for the consumables (paper, toner, electricity). The paper is recyclable. At one page a day, I would guess lifetime will be dominated by mechanical lubrication or degradation of capacitors, dust clogs, etc.

Hundred dollars for the printer, I think Zou are absolutely over spending here. Electricity can be saved by having shutoff and turn on with a timer.

That could be actually nice!

You definitely need to be able to make out an Information Radiator from across a room. We’ll probably see a tipping point somewhere around a 30” screen, where you can put a large summary at the top, and details farther down.

Is anything going on? Is it worth me crossing the room to see? Should I be checking my email, other dashboards, or coworkers?

This morning when I awoke, my wife had propped up her ebook reader on the nightstand next to me. It looked nice. I thought: how cool would it be to have a little e-ink display to which I could beam a few key pieces of information?

Beautiful project!

Nice, but I can't think of less power-efficient embedded platform than an RPi. Especially with something as low power as E-Ink (zero power when displaying).

Innophase T2, Dialog DA16200, RedPines (SiLabs) RS9116, RealTek Ameba... they all are super low power (like 100x less than RPi) even while maintaining the 802.11 association, and come with easy SDKs ready for REST HTTPS out of the box (and RTC capabilities, not sure about the ameba).

Sure, there are more power efficient platforms, but the project uses Selenium and PIL which I’m pretty sure won’t run on any of those boards.

I guess you could offload the rendering to a server, but then it’s no longer a self-contained, standalone solution. Trade-offs!

How does ESP32 compare to the products you listed?

I find the ESP32 much easier to develop for, you don't need to install any toolchains, just plug in and drop code into the virtual USB drive that shows up! I wish all microcontrollers were like that these days.

That sounds like a very specific bootloader that you're using

ESP-IDF is still very nice though, and being CMake based makes it easy to integrate outside code

It supports serial based uploads, which are still pretty nice with the bundled serial monitor (one key combo to build, upload, and restart) and OTA uploads

Oh sure, but it's still way better than the last time I had to deal with an STM32 and install about 5 different things, modify a "boards.txt" file (which there were 3 copies of on my system in different places and I had no idea which was the real one) and then hit the program button with one hand with a mouse in the air while carefully timing a short of a reset trace on a PCB with the other with my elbow holding down the PCB. STM32s really suck. Never had to do that with an ESP32, at least someone made a nice bootloader for it.

How do you handle SSL? I found this very cumbersome in my experiments with esp32

I never coded on Espressif, but in other SDKs (e.g., mosquitto, mbedtls) typically this is done when you open the connection at the application layer (HTTPS, MQTTS). You pass in the cert bytes either as binary or PEM text as a char[]. Use a CA root cert(s) from your OS/browser.

EDIT: grammar and typos.

It depends on whether you want to connect to random hosts or ones that you know beforehand. The latter is very easy, I just hardcode the certificate fingerprint. The former/dealing with CAs is harder, I've never done it.

The high-level client in esp-idf handles ssl out of the box and comes with a list of pre-installed root cas.

The question, of course, is: What if these CAs expire?

ESP32 is a very generic synthesized chip, not particularly ULP oriented.

On other hand, it's the most developer friendly company out there.

I've been unsuccessful getting any proper reaction from Innophase about SDK support. Their sales seem to not even understand what we are wanting from them, and keep sending us "enter these AT commands through USB-TTL"

ESP32 is also pretty much the one, and only wireless MCU you can buy on the open market, in any quantity, on a short notice. Nothing else comes with the supply chain security like this.

> ESP32 is a very generic synthesized chip, not particularly ULP oriented.

Maybe not, but setting it up to sleep most of the time and only boot once a day to fetch the calendar and update the display should sip power pretty sparingly; I expect you'd get months if not a year or more before needing to recharge the battery.

I wanted to try their Espressif ESP32 low power 802.11 part back in March but it wasn't shipping yet. Their website isn't clear but I'll poke around and see if it has been released yet.

I was going to say, I feel like an ESP32 might be a better fit for this, given that it’s designed for deep sleep.

Can you keep RPi most of the time hibernated? Does it still draw a lot of power in sleep?

I don't think it has a hibernate mode, but it has been a quite a hwile since I've downloaded the latest headless server build.

I am currently reading 428mA at 5.0V on the power supply that is driving it. It is headless and I'm not interacting with it. (400mA w/ethernet unplugged). So that's 2W. I'm running Buster Debian build. If you got a low power command, hit me with it and I'll try it! systemctl doesn't support hibernate. I don't do any low power linux programming mainly because Cortex-A class processors (heck, even M7's) are already far outside my power budget.

That is a crazy amount of power, compared to the InnoPhase T2 that draws ~300 MICRO Watts when connected and sleeping.

You don't really need to "hibernate"; shutting the entire system down and booting from scratch on each update is simpler and probably more reliable.

The problem (hibernate or not) is getting the Pi to wake up, since it doesn't have a real-time clock. OP is using a RTC hat to achieve this. I do wonder what kind of power consumption it uses while sleeping.

what a colossal kludge. what you're trying to accomplish is basically embedded programming 101: sleep mode + wakeup timer. RTC? pff.. even any MPU on-board oscillator with no crystal has good enough PPM and lower power than an RTC. your solution is like hunting quail with a nuke.

yes, but trying to generate a nice rendered image on a stand-alone uProcessor is pretty hard.

I don't like that it takes headless chrome to render, but it _works_ and fills a need for the maker.

I'm pretty sure they looked at the stuff they'd need to write (A layout engine, a anti aliasing library, a calendar parsing library, an image handling library) and thought "fuck that, lets use a pi".

It terms of time thats weeks full time, and even then might not be possible to fit on the uCPU of choice.

just buy a realtime hat with wake up ability, for $40 max, boom job done moving to making the thing look good.

Its not a product, its someone's hobby, leave them be.

> trying to generate a nice rendered image on a stand-alone uProcessor is pretty hard.

Did you see the rendering? It is very simple, and does not require PIL. There are plenty of embedded GUI libraries that are specifically for this kind of application (uFX, Qt). Why not learn something new?

I want HN to be a place where experts critique ideas, not a Facebook/Instagram like-fest ego-stroke. I was proposing a deeper dive to the OP so that s/he could develop better skills. I wasn't mocking OP, but I was mocking your bad idea because you didn't make anything, you just threw out a naive suggestion.

Did you come here to learn or to get some karma for a dopamine hit?

> I want HN to be a place where experts critique ideas

I was critiquing your world view that _everyone_ must at all times go really deep into software so that everything can fit inside 4mbit of flash.

I was also also critiquing your strongly held opinion that simply because a microprocessor has low power states, it doesn't mean that its quick, easy or indeed achievable to render a nice calendar entirely onboard. (it is of course possible, but I know it would take me a lot of time and be no fun.)

Perhaps the goal of the project was to get something that looked nice in a time frame that was reasonable. Perhaps the goal was not to spend time learning how to do antialiasing, font handling, calendar parsing in a power constrained environment.

The joy of the internet is that they have shared their work, now you can build on it and make a good looking eink calendar that's battery powered on some tiny ARM SoC with 4kb of ram.

Whilst you're at it, I propose that you go out of your comfort zone and remake this https://www.secretbatcave.co.uk/projects/stock-ticker-machin... to make it purely electro mechanical. it can't be that hard.

This very article shows how they use another product that just turns on the pi on a schedule (once a day) to render the updated calendar.

Nice project & explanation.

I can see myself expanding on this (maybe even re-hashing your library essentially) running:

1. a Calendar,

2. next to a Stock Ticker,

3. next to a Financial accounts (i.e. all current asset) combined with Financial goals.

I've been thinking about the third one for a while. E-Ink / a simple, low power, monochromatic screen (similar to Amazon Kindle eReader) would be a good choice.

I’m not 100% sure how well it would work, but pointing an old kindle at a auto-refreshing web page might get the job done.

IIRC someone on HN once mentioned that the Kindle web browser has a memory leak that will cause an OoM error/crash every (1000?) refreshes. They had a workaround but I forgot what it was.

This calender-thing really seems to resonate with people!

I built something similar but more versatile, where you can either display images or feed the display with whatever information you want remotely. And it runs on a battery for a whole year:


Really well done!! Looks great. Although price seems reasonable, it is still quite a lot of money.

Did you actually sell screens already? I can imagine design stores want to sell this.

I went online about a year ago. So yes, I already sold a lot of devices.

When I was at Google I worked with the developers of the Radish project [1], which was installed all over at the time. It's amazing how far the state of the art has some since then. Aaron told me about the memory constraints - The Radish streamed data to the e-ink display's memory buffer to update, powering it on to do so only briefly, while a Pi Zero is plenty enough to render the whole display. We've come a very long way.

[1] https://developers.google.com/gdata/articles/radish

Looks great, IMO you could bring down battery usage by using an ESP8266/ESP32 instead of a Raspberry PI

I'm delighted to see the e-ink displays prices coming down, even though it's coming down a bit slowly.

Imagine wallpaper sized e-ink displays.

would make for some amazing, decorative art.

I'm planning on setting up an all-in-one touchscreen+computer+monitor ($300 on eBay) as a glorified family to-do list manager and photo frame... any software recommendations would be appreciated! (For instance, not sure how well supported the touch screens are on Linux, etc.)

Is e-ink fundamentally more expensive to produce, or is the quantity produced just not enough right now?

I remember reading somewhere on HN that it‘s a patent/monopoly issue but I didn‘t verify.

I wrote a similar project that generates Gameboy art from a collection of roms on a Raspberry pi and displayed them on a 8 color E-Ink display.


This is awesome! I'd love to build one. But I would probably like to have it plugged in, so I could update it more regularly with Spotify and some info from Home Assistant. The only problem is that I can't find Raspberry Pi Zeros anywhere. I tried ordering one yesterday to make a little Spotify Now Playing screen, and they're out of stock everywhere I looked.

Seems like an ideal use for a large e-ink display, useful reference information that doesn't change often. Cool.

The e-ink displays are a bit costly. Otherwise I would get a few of them and would replace all the paper calendars at home. Simply a calendar, no internet, low power. Not raspberry PI based, some low powered microcontroller simply displaying a paper like calendar and nothing fancy.

Great idea. Will be great to have hackable audio player with big battery 'cause it's hard quest to find one with good audiobooks & folders support.

Why not use a raspberry pi connected to an hdtv to display this, weather, news, etc.? You could make one HDMI port the "what's happening" channel.

Plus run pinhole.

It seems some of us are more averse to LCD screens than others. For an always-on ambient advice, I appreciate that epaper can match the lighting of the room and not draw attention to itself (instead of basically being a flourescent bulb)

This looks like a desk calendar. e-ink is low power, allowing you to build a portable unit running on battery. And it has it own distinctive look, which some may prefer. Though yeah, an hdtv version would be lot functional.

You know what would be cool? An e-Ink glassboard. You need a graph grid? Check. Need a smaller grid? No problem. Stylish picture, sure.

This is a beautiful piece! We need a better design than the 30-box view. How useful is it to see “Appoi…” on a Thursday?

• Displays one month

• Needs battery change more than monthly

I.e. it’s still less work to have a paper calendar and flip a page every month.

> I.e. it’s still less work to have a paper calendar and flip a page every month.

Is there a plugin for paper calendar so it will automatically sync with my Google Calendar?!

Install the "Handwriting" plugin on the human component. It's slow, but works reasonably well.

No. That’s a feature.

Well, I mean, it also syncs automatically with google - which is kind of the whole point.

Do you feel this comment has contributed anything to discussion around this post?

Yes. The continual obliviousness which product makers (and buyers) have towards battery life is very annoying. I used to have a wristwatch which was the most technically advanced watch I could find, and it had a touch screen and various applications. Its battery consistently lasted for more than two years after each battery change. Eventually the touch screen wore out, and I stopped using it.

I can’t stand all this modern hardware which must all be charged after a few hours of use. It’s a continual stress factor to keep track of the charge of all your various devices.

I would love to build something like this but the price of these screens is insane :(

Super cool concept, thanks for sharing!

Is anyone making E-Ink displays for NFTs?

The first thing I always do with these E-Ink projects is to check the price of the display, to see if it's come down at all since the last time I checked over the last 3+ years:

> Waveshare 12.48" Tri-color E-Ink Display - $179.99


The price of displays has come down. Color e-ink is new tech, and as such is more expensive.

Problem is - three-pigment e-ink was a new tech 10 years ago and still of luxury niche.

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