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Show HN: E-Paper 7-color display showing the current weather

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229 pointsblixt93 comments

A hobby project of mine that was surprisingly easy to put together! I love waking up and seeing the freshly generated image.

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I use the Inkplate 6Color for some similar projects. Built-in ESP32 controller, so no Pi required. Can be fully battery-powered, so if you make intelligent use of the deep-sleep/wake schedule, you can stretch that battery charge for a couple of weeks. My favorite one is a red "On Air" sign that hangs on my office door (used for meetings and recordings.) I just trigger a shortcut on my Mac and it automagically updates my status and mutes my devices. They have example open source projects for weather displays, news, Google Calendars...

https://soldered.com/product/inkplate-6color-color-e-paper-b...

Cheap e-ink projects are super fun and useful.

I have a similar project too! I have an e-ink display connected to a Pi Zero that shows just a "Yes" or "No" telling me if it's going to rain outside in the next three hours. (On a second thought, maybe I don't need a 7 color display...)

My display is this one: https://shop.pimoroni.com/products/inky-impression-7-3?varia... which seems to be cheaper.

Nice, super clever use of it! Yeah it's super fun and makes me want to put these screens all over my house.

holy crap! this hits all the checkpoints

edit: shocked at the prices!

All of the cool e-ink projects I want to do fall apart when I'm reminded of the cost of e-ink panels.

What was the name of the eink computer that was on here last week? I can't find it back for the life of me. I desperately want a flat white display for work. Reading technical grant proposals on a regular screen is killing my eyes.

Maybe https://daylightcomputer.com/? There are also monitors such as https://shop.dasung.com/products/dasung-25-3-curved-e-ink-mo....

Modos laptop?

Yeah I keep checking the prices of them to see if they come down but nope. Meanwhile you can get a touch tft 3.5" for like a dollar.

He said it is cheap, so don't worry about the ridiculous price.

Meanwhile you can get an esp32 + 2.8" tft screen + sd card for $15.

OK this is uncanny, I independently made the exact same thing with the exact same display a week ago:

https://imgz.org/iBLADkCU.jpg

It's a frame that fetches the current weather and time at a location, has AI generate a photo with that location, and shows it.

How did we both independently arrive at this? I guess it was the most obvious thing to do?

This is a case where ideas are "all around" - it's the kind of example that's wonderful for a new entrepreneur - to see your idea isn't unique (very few are). Execution matters.

Y'all like the Uber and Lyft of eink weather - but I've tagged others like this from HN.

Edit: soon as I find the time I'm building one too - all are inspirational for esp32 dev + key for FOSs home-automation

Cool hardware project and idea, but I'm not touching an OpenAI API with a ten-foot pole, especially for an always-on device

Maybe when I need a fun project I'll make a version that uses OpenStreetMaps + LAN-hosted Stable Diffusion tho, so worth a bookmark to remember to do that

What's wrong with OpenAI APIs and always-on devices?

Trickly cost center a corp that's already betrayed me multiple times gets to set the price on. Also I have a hardline policy that I won't interact with Microsoft in any capacity for less than $80/hr, and that's the friends and family discount

Ah, you're afraid of sudden price changes? That makes sense, though (at least for my frame) I cache the responses, so after a few days I don't make any more API calls, everything comes from the cache.

Limiting contamination is a good first step, but I'm of the mind that anything that doesn't need a cloud service shouldn't use one. To each their own though

Thanks for posting! I picked up two of these same displays after seeing similar projects here that used them:

- "A WiFi color eInk picture frame" https://news.ycombinator.com/item?id=35689706

- "Color E-Ink Display Photo Frame Pranks [Mom]" https://news.ycombinator.com/item?id=26977747

I was planning to turn them into color photo displays like in those two examples, but this is a neat application too.

Thank you for sharing – I love that the second one also has a microscope closeup of the display while it's changing. Happy hacking, hope to see your projects on here soon!

The image displays Barcelona with 26°C and 2°C.

I've been to Barcelona a couple of times and it's hard to imagine a day where you hit both temperatures?

Is the weather data in any way reliable? Or is it all just hallucinated stuff and I should just enjoy the animations? It could also be that I know Barcelona weather less then I thought and it's possible to hit 26 high and 2 low?

Yeah this is Dall-E incapable of cleanly writing text. The 2 C is just a “hallucination” from the 26 C. This is a hobby project and as such I prioritized the text looking unique every time (and usually more artistic than in that image), rather than put a traditionally rendered text on there, but image generation models are not good enough for this use case if you were to make a serious product out of it.

It is certainly beautiful, would be good if it was correct, too :)

“Don't leave the same image on the display for too long.”

Why is this? Is it something particular about colour e-ink?

The recommendation from Waveshare is "refresh at least once every 24 hours"[1]. It's probably not such a big deal in reality, but maybe there's some risk of the pixels getting stuck if they are active for too long?

[1]: https://www.waveshare.com/wiki/7.3inch_e-Paper_HAT_(F)_Manua...

Are they “active” when set? I thought part of the point of e-ink was that it would maintain its image without power applied.

Nope, it's a completely physical process and state, so you can disconnect it and the image will remain the same. So you could use it as a reusable post card if you wanted, but for $80 maybe it's not such a good idea...

I don't really know why they recommend to clear the screen after leaving the same image in for 24 hours, but I think it's mostly a precaution and most likely not a real issue. But for my own sanity, I do clear it at 2am and then it's already drawn a new image at 8am, before I'm out of bed.

I had some “burn-in” on a 4 in waveshare display that lasted for about 10 refreshes. I bought it used so who knows how long it was stuck on that one screen

Because it burns in, or because it fades out?

There a difference in how the display works that’s different to a monochrome one, that requires the caveat of “don’t leave the same image on the display for long”?

If memory serves, standard monochrome e-ink displays don’t suffer from burn-in.

I'm just parroting Waveshare's own recommendations[1], but yeah probably it's not such a big deal. I'll link their docs in the README to help people make a more informed decision.

[1]: https://www.waveshare.com/wiki/7.3inch_e-Paper_HAT_(F)_Manua...

Does anyone know why projects like this always seem to specify using a particular type of tiny, low-power computer (usually a Raspberry Pi or something similar) to drive the display?

I already have plenty of non-tiny computers that run Debian GNU/Linux. Suppose I wanted to run an e-paper display from one of those computers, using this code, just via a normal USB cable. I could do that, right? There's no reason I would have to use a Raspberry Pi or something similar?

Small computers like RPi make it easy to access the low-level peripherals such as SPI, which this small screen uses, and others like GPIOs. If your big-computer has such peripherals available to the OS, you can use them also. Before small computers, you could use the parallel port (and some small program) to talk to your own peripherals via the same low-level signalling.

The other extreme would be nice. Something very low powered that can spend 99% of its time in standby. Then you could run the whole thing on a battery for months. For a weather display, waking up for a few milliseconds per minute should be enough.

The 7" E-Ink display is US$86, which is not too bad.

Got it -- I appreciate the explanation.

There's no reason at all. RPis come with lots of bootstrap documentation and code so it's comfortable for someone that's played with Linux to get one running, install some packages, and make it do something.

You could do this with a tiny microcontroller if you had the time and knowledge to do it. There's nothing magical about the displays other than strange supply voltages at times.

The more common problem is that they don't listen to USB. They take SPI or parallel digital interfaces to set the pixels. So you need some kind of intermediate interface and software to draw the display. Which is why people just slap an RPi into the mix and talk to that over more common protocols.

Thank you. My idea was more the opposite: do it with a normal laptop or desktop computer driving the display, rather than a tiny microcontroller. I guess I'm assuming that either the display's USB input supplies enough voltage to run the display, or that the display has a separate power supply -- i.e., that there's nothing magical about a Raspberry Pi that makes it supply special bits or special voltages to these displays that can't be supplied by, say, my desktop computer.

Edited my response above. The answer is more about the interface that these displays require.

AHHHH, that's the key thing I didn't know (I have a Raspberry Pi sitting in a drawer and have played with it embarrassingly little -- I didn't realize how important having the SPI or other special interface is in this context). Thank you again.

With that said, though, there are also tons of inexpensive ways to output SPI or various other serial protocols from just about any device with a USB port, like your full-sized computer: https://www.adafruit.com/product/2264

The RPis and friends just optimize the workflow - theres nothing particularly magic about they way they implement SPI or GPIO, they just have it out of the box because its such a common way to extend hobby computer boards.

Just ordered. Thank you :-).

The refresh rate of these displays is 0.03 fps.

My first thought for a project like this (grab photos/data from the internet, display them on a device) would be a Pi Zero 2 W or a Pi Pico W, for the reasons you stated.

I'm not particularly up to date with the tiny microcontroller ecosystem - if I wanted to execute this at lower cost and/or lower power, what would be some better options to consider?

Because they are cheap and run on battery for a long time, and it is stupid to leave a computer running this display on.

Neat, thanks! What a great project, and like any excellent project it helps get somebody on a path to customization. The hardware recommendation and even just epaper.py[1] is nice to see as a reference. Thanks for sharing!

[1]: https://github.com/blixt/sol-mate-eink/blob/main/epaper.py

I'm struggling to work out why this uses AI for getting the weather?

There are dozens of different free weather APIs which could be called directly.

It uses AI for some things you can't really use free APIs for:

- Turn a colloquial name for a neighborhood into the exact latitude and longitude (I'm sure there's some API that can kind of do this but I don't know a free one that is as accurate as GPT)

- Adding to the previous point, if you say "Hogwarts" or "Tatooine" it will dutifully give you the weather of those too thanks to AI [1]

- Most importantly, write a Dall-E compatible prompt to generate an image with the actual weather conditions (and sun/moon etc)

[1]: https://x.com/blixt/status/1724099967361462714

From your first point, I'd expect you to be using a service that provides the weather for a given latitude and longitude.

From your second point, I'd have expected that to fail for Hogwarts or Tatooine.

Taken together, it sounds like you're blindly trusting the coordinates generated by AI, and will happily generate correct-looking results for any input. I'd call that hallucinating the weather. If I type in "Springfield" I'm gonna get results but I'm not gonna know if they're mine.

This may be an unreasonable level of concern for a fun app.

I do use a service for getting the weather (backend: https://github.com/blixt/sol-mate)

Yeah the second part I consider a bonus. Especially because I can use street names or slang for locations that no rigid API supports.

> Taken together, it sounds like you're blindly trusting the coordinates generated by AI

Actually I guess I do "blindly" trust the AI's coordinates more than a traditional location search service. Not sure how much you've tested it yourself, but I haven't gotten a single false latitude/longitude pair from GPT-4 unless the location was truly ambiguous, in which case it would be one of them. But as a European, I've definitely experienced rigid APIs happily giving me the weather for "Stockholm, NY" which apparently does exist, but wouldn't have been my first option...

But yeah, it is just a fun app, so I wouldn't want to make it more rigid either way!

Have you stress tested it? "Springfield" is a very common name in the US. I'd love to know how it handles "Sandwich" as well.

Again, probably overboard for a fun app!

They're fair questions, and yeah it will have to disambiguate in such cases. I tried it now and it picked:

- Springfield in Illinois

- Sandwich in Massachusetts (the exact coords: https://www.google.com/maps/place/41%C2%B045'31.0%22N+70%C2%...)

I think that people underestimate how much non-AI technology fails in these cases. And the recovery path is to retry with more specificity in either case.

> I think that people underestimate how much non-AI technology fails in these cases.

That's an excellent point!

Just browsed through your code and I see that you're calculating the positions of the sun and moon. Very cool! Really fun project!

Of these, only the first one actually has any real value. And as you've mentioned there are likely less "expensive" ways to do so. By expensive, I mean this is essentially using a sledgehammer to crack a nut (especially the Dall-E call).

I don't understand how I would get a unique but accurate prompt that makes Dall-E produce an image that besides the weather/lighting conditions also has a randomly picked iconic scene for the location, people in the picture that have the correct clothing and doing reasonable activities, etc.

I'm trying to understand the criticism here, so please give the GPT a shot with a few different locations (you can also do neighborhoods or fictional locations) and describe how this is a nut that can be cracked with non-LLM solutions:

https://chatgpt.com/g/g-QIydQSFRm-sol-mate

If your goal was wanting to use AI image generation to create such an image, this makes sense.

I think people are just questioning the assumption that such a feature is a desirable or necessary feature of a weather display.

I definitely was a bit surprised to open the repo to a weather display and see the need for an OpenAI key without an explanation of which features were AI-powered.

But of course this is a personal project, so "Generate a representative AI image using the location and weather information" is a perfectly valid, and cool, challenge to set yourself and achieve.

Google images? You could run a classifying model if you wanted to segment by time of day and weather.

Moistere Vapeers, very believable.

It’s a very useful line to have on a CV.

Or you can just look at the window.

My favorite is the weather station consisting of a rock sitting in a dish suspended by a chain. If rock is wet, it is raining. If rock is moving it is windy. If you can't see rock, it is night. If rock casts a shadow, it is sunny

More details: https://en.wikipedia.org/wiki/Weather_rock

Thanks! I should have known that it would have a wiki entry. Although, I think some of the rules are a bit meh. "if rock is warm" you're not meant to need to touch it as it's meant for a quick glance kind of tool. also, as it mentions, the rock is a finely tuned instrument, so thank you for not touching.

if the rock is gone....tornado.

I appreciate that it's just a nice picture that happens to update with the weather, but there's no reason to only use this for your current physical location. It accepts any place in the world (and also fictional places), so you could see a picture of what it looks like where your distant family member or friend is, among many other things.

When I look at the weather app, I don't need to know what the weather is now but what the weather will most likely be later when I'm outside.

"Stocckholm". Also Santa Monica has at least one giant man, and on the beach there's a centaur, but I guess these little glitches add to the entertainment value.

I suppose I don't understand how colors work on e-paper at all. Can these 7 colors not be dithered? Or even mixed more properly, for something like true color functionality?

I use Floyd-Steinberg dithering, and if you look at the "More images" section you can see it does a reasonable job at representing colors. Also worth nothing that 2 of those 7 colors are black & white, so questionable naming perhaps.

I'm pretty sure real production use cases of these screens don't tend to use dithering though, focusing on contrast and readability.

The naming is a hard problem - black/white/orange and black/white/red screens are commonly called 3-color screens, to distinguish them from normal black/white screens. Calling them 1-color screens would be an awful choice of name, but "7-color screens" is a name consistent with the "3-color screens" name and calling them 5-color would be horribly confusing (especially since current 5-color would become 3-color).

Also, black and white are their own specific primary colors, they're not made out of a combination of other colors, so it's rather appropriate to call them colors in that context.

What are the power requirements for the build? Could it be run off one or more 18650’s?

If using the Raspberry Pi 5 I wouldn't go for a battery-powered solution because it's pretty power hungry. But you can run this screen just fine off of a Raspberry Pi Zero, or ideally a microcontroller if you want basically no power draw while it's sleeping. I was just lazy.

The similar project I'm working on is looking like it'll get about a year of battery life with a typical 18650, the 5.65" version of the display and run off an ESP (refreshed once a day).

The e-ink review say the display has a dark purple color. How is your experience?

I asked it to generate the weather for "The Purple Forest" (Narnia) and this is what it came up with:

https://i.imgur.com/kmKiqbO.jpg

You can zoom in on the purples. I would say it looks like a wine purple IRL.

I’m sorry I was not very clear with my question. The review is negative- saying the ‘white’ is more like a dark purple color. I’m not asking how well it shows purple- but the general quality of the display itself.

My bad, I understand now! I think it's at least as good as a Kindle. I understand why someone who is comparing to bleached paper or OLED/modern LCD screens would say it looks purple, but yeah, I have no complaints.

Edited to add: In the picture you can also see the white material at the bottom that is not part of the screen, I would say that is "true white". And the picture also has white pixels on the screen. That's the "dark purple" the review refers to in that case.

Yeah, that's pretty purple for white. But still amazing how far this tech has come.

Wow, these have come a long way.

The black does have a purpleish tinge on my panels, but the other colours don't. Overall it's pretty low contrast and saturation, and unable to reproduce cyan or fuchsia even with blending through any kind of blending, which makes certain things like sky and water come through poorly.

I made a palette for colour space conversions for reference: https://imgur.com/a/2vgFsT4

$86 for 7-colour 7.3" RPi compatible e-paper display. That's not bad.

Congrats, it's awesome! I've starred the repo to use some ideas.

Beautiful. The prompt in the GH repo is the same you used in your custom GPT?

Since GPTs only have the one prompt I had to specialize it for a multi-step process with tool use (since it has to call an endpoint and draw an image in one go). Here's the prompt that I use in the GPT:

https://gist.github.com/blixt/44bbed23bee7f65b53fd3304781edd...

Thank you very much.

First prompt: https://github.com/blixt/sol-mate-eink/blob/1236dbb66b80c838...

> Get the weather data for {location}. If the location is not on Earth (fictional or otherwise), pick the place on Earth that is most visually similar to the location. Before you get the weather, reason about which temperature unit is most likely to be used at the location in question. That is the temperature unit you should use when getting the weather.

Second: https://github.com/blixt/sol-mate-eink/blob/1236dbb66b80c838...

> Here is the weather for the location "{location}":

> {weather["status"]}

> Use Dall-E to generate a beautiful illustration of the location in the style of a wide post card filling up the entire image. Try to describe a scene that is iconic and aesthetically pleasing for the location specified above, but also one that can showcase the weather. (…)

Really nice color palettes. Some reminds me if MUI on the Amiga.

I never realized just how thin these displays are. Very cool!

Nice work! Beautiful use of the display.

Totally off topic because this is v cool, but what’s the use case for things showing the current weather? Forecasts I get, but current? Lots of phones and even Windows 11 prominently display this information but who is it for? People who work in windowless offices or something?

I mean it’s a bit like a restaurant menu app that only shows you pictures or what you just ordered, right?

Many taller buildings don't have a way for you to step outside in an outfit to see if it works for the weather. Or to step outside for a few minutes to try to manually gauge the temperature with our squishy body thermometers.

If you know the temperature, you don't need to do this exercise at all, you simply know based on experience, and it's more accurate, too. A few degrees difference can mean different clothes, different materials, different layering, etc.

I mean cool and all, but as an electrical engineer literally shaving off microamps from my design I can't help but wonder what the energy use behind the AI-generated backdrops is. After all we have kinda a situation as a planet.

Does your room have a window? i am trying to understand the earth

I love windows! And doors. And pictures that update in response to the weather.

Like a news paper that get tossed right through your window onto your desk! I love all those too thank you!

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