Yet another E-Ink weather display – but with Rust | Hacker News Reader

Yet another E-Ink weather display – but with Rust

harrystern.net

196 pointsboustrophedon67 comments

I'm a simple man, and did something similar but with bash+mosquitto+imagemagick running on a Kindle. That's boring/been done, but what I want to talk about is screen burn-in.

I've been displaying slight variations of the same image on an old Kidle paperwhite for a bit over 5 years! I've noticed NO burn-in at all. I'm doing partial updates every refresh (30 second refreshes), so the display will go 1+ years without a full refresh (~1 million partial refreshes a year). There's some retention when I first work with it, but clearing the screen and showing a full-screen pattern is enough to remove that retention entirely.

Pretty impressive, and I am also impressed the old firmware stays attached to wifi for the whole time as well! Sometimes it can have trouble reconnecting (power outage, dog unplugged wifi, whatever), that's when I'll see if there's burn-in, probably once a year(ish).

I would love to see your setup. I had a similar thing going on, but I used my own SSH based broker.

I'm a simple man. I see an eInk IoT project on the front page, I upvote.

Very nice work! It's beautiful.

Thank you! I was really impressed with how well the print came out with just their "coarse smoothing" option.

I'm a simple man, I see "but with Rust," I upvote.

judging by the front page in recent years you are not alone

Idea for a product I would buy, maybe it exists already:

E-Ink screen and an ESP32 in a white case, i.e. similar to what this guy has built. Programmable via USB-C. So I could buy this, program it to display something and put it on my wall.

Could be a range of different sizes.

This is going to sound weird, but the first color changing LED lights I ever thought were worth a damn I found at Ikea. There are probably half a dozen decent ones now, but at the time it was Ikea or something that cost three times as much, which was ridiculous.

https://shop.m5stack.com/products/m5paper-esp32-development-...

That exists: Inkplate10

Did mine with Rust, too: https://imgur.com/a/NoTr8XX

Was fun.

Yours looks way better than mine - I intentionally didn't show the inside because it's a mess of wires and the screen is held on with masking tape and blue sticky tack and the waveshare esp board wasn't really designed to be soldered to.

Initially I was also going to use an external RTC but didn't want to have the additional circuitry to actually turn on and off the esp32 via the RTC's interrupt signal. Did you find that the internal RTC on the esp wasn't accurate enough?

> Did you find that the internal RTC on the esp wasn't accurate enough?

It's more the power savings I was after :-) I wanted to put the esp32 into the deepest possible sleep state, which involves turning the RTC/RTC memory off entirely and is a pretty big drop. The external RTC I picked has a much lower current draw.

The esp's RTC is quite inaccurate, but certainly good enough to ballpark "morning update" and update system time to re-calibrate then.

Is there a way to fully turn off the RTC on the esp and still go into sleep, or are you using the external RTC to enable/disable the chip itself?

I noted this in the "future work" section but I don't have a way to actually test or validate whether the various deep sleep levels are working. If I try to use the ammeter on a standard multimeter it can't cope with the changing ranges as the esp draws a bunch of power to boot and I think probably causes brownouts.

Do you have a current ranger / ucurrent gold type device?

What I do is basically:

- Put it in deep sleep

- On top of this, turn off the power domains for the RTC peripheral, RTC memory and the XTAL oscillator manually

- Use exlusively the ext1 external wakeup (ext0 requires the RTC peripherals to be powered on)

From my reading of the spec sheet, this is the best you can do on the chip.

Note that my choice of RTC also factors into the equation, the RV-3028-C7 has a significantly lower current draw than the common DS* RTC chips you see on maker-type boards.

And yeah, I bought a CurrentRanger :)

I'm very lazy about charging devices (I'm one of those people that keep their bicycle mechanical instead of going with the trend of electric shifters, because I absolutely don't want that hassle), so my goal was to maximize the number of months I wouldn't have to touch it.

Thanks for the explanation! I didn't know it was possible to turn off the crystal at all.

Maybe I'll splurge for a CurrentRanger as well. I'm definitely on board with changing batteries as infrequently as possible.

I love this project, and I really want to setup one in my office. Your post says you'll be open-sourcing your code; have you done that yet?

Still haven't! Pregnancy & first child came in the way :-(

I tend to go pretty obsessive with these release (e.g. https://github.com/eikehein/hyelicht), so it takes some time ...

I also came to ask about source, but looking at hyelicht -- wow! Worth the wait I suppose!

Why E-Ink isn't cheap yet? I see supermarkets using hundreds (maybe thousands) of panels with different sizes for displaying prices. I doubt they are paying 50$ for 7" display panel.

Manufacturing scale for some standard sizes probably isn't high enough.

I also want to know how much toxic shit it takes to make E-ink.

And part of me doesn't want to know.

They were highly patent encumbered for a while. I think much of that is expired but the manufacturing base hasn’t caught up yet.

The pricing is pretty expensive even in bulk. $50 for the larger displays isn’t off by an order of magnitude (e.g. 7 inch with red) especially as a retailer is buying that as a larger solution which includes all the syncing hardware, maintenance programs, and integrations.

For retailers, the savings story is in increased pricing accuracy and reduced labor for price changes. There is the promise of dynamic pricing but that’s a minefield for various reasons.

That’s why you tend to see it in high-value retailers (pricing accuracy, precision, smaller tag count) and grocers (lots of price changes, high labor costs).

It looks it is due to patent [1]

[1] https://youtu.be/1qIHCUWAgh4

I'm also a simple man, maybe the simplest here on HN. I see numbers on a graph that don't fit the red line on the graph and the lack of any scale for the data under the shaded area and I think WTF? I know this is an example but the data doesn't fit the numbers annotated across the top at all.

I also see Rust and I reach for WoolWax. That's just me though.

This is a cool project. I have been thinking of something like this using an old e-Reader.

I could have explained that better. The numbers on the Y axis indicate the min/max for the week, and the ones next to the days of the week are min/max for the day. The temperature graph is also scaled to not go all the way to the top of the graph. It's entirely possible that there's a bug in my code though - I didn't really write any unit tests for it.

The shaded area is a percentage and does extend to the top of the graph region, which means 100% chance of rain.

Thanks for the reply. I have marked up the display example [0] that you show in your post to highlight some of the issues that popped out at me.

From the mark-up it looks like the data used for drawing the red curve and for annotating the - Day High Low - for temperature may have come from a different set of days since they don't fit well in the graph area. The low temperatures for each day are especially wonky.

I also noted that sunrise appears to be around 5 am at your location based on a quick attempt to define a horizontal scale for hour of the day. I don't know if that is correct.

I hope all this helps. I really like that red line capability. That is one of the things that to me makes using an e-ink display less than ideal. I like to be able to use colors to help define the data being graphed or displayed.

Good luck with this project. It is pretty cool.

[0] https://imgur.com/a/udoKsfi

Thanks for the detailed markup! I'm going to take a look at the code tomorrow and see if there's some obvious mistake I've made with the highs/lows. I do remember doing some filtering to only show the lows after noon because I'm typically not outside at 5am - maybe I messed that up.

The reason the current temperature is higher than the "weekly high" is simply that the current temperature is from actual observed data and the weekly high is from forecasted dated, so there are two possibilities: either the temperature is simply higher than forecasted, or the current temperature is higher than it will get the rest of the week.

For what it's worth, there are multicolor e-ink displays available at similar sizes but of course they're also more expensive and have longer refresh rates.

What's the advantage of Rust here? Like, I thought there was a bunch of more "native" tooling around ESP32 (Arduino?). Do the "neat" parts of Rust carry over into work on these small/embedded systems? Or is there a lot of fighting the toolkit because the vendor supports only C-libs?

The vendor toolkit is in C, so often you'll see for newer boards that Arduino/CircuitPython/etc don't support it yet because they have to build their own wrappers. Rust lets you use bindgen to basically immediately have access to the entire vendor library.

Now, in this case I'm using an older esp32 board so something like CircuitPython probably would have been equally fine, but it was nice to be able to share the same buffer type across the server and client. I also just enjoy writing Rust and find it less error-prone than C.

Does anyone know what fontface this project uses, I tried searching the repo but I found nothing

It's https://fonts.google.com/specimen/Comfortaa

Fonts are in https://github.com/boustrophedon/eink-esp-weather-display/tr...

Thank you very much

Comfortaa Regular - https://fonts.google.com/specimen/Comfortaa

I searched the repo for "ttf".

Thank you very much

I'm a simple man, i just want to know where he lives that the high and low temp for a day are the same. Don't think i've ever seen that happen before.

It happened a couple of days ago in northern Virginia. It was rainy in the afternoon, which brought the high down.

Bringing the high down is one thing. Having a flat line, with less than 1 degree deviation, for the whole day is another! Or perhaps "low" isn't calculated this way.

I think you're technically correct, but "low" and "high" are often just used as shorthand for "what temperature it will be in the morning" and "what temperature it will be in the afternoon," respectively. A weather app may just be reporting the expected temperature at 8 AM and 3 PM, even if there are lower lows or higher highs at some other part of the day.

Somehow I completely did not notice this - this must be the bug another commenter (doodlebugging) is talking about.

Thanks for pointing it out!

If anyone knows a 3d printing service in the US that does prices comparable to JLCPCB I'd be glad to get some recommendations!

Many libraries around me in the Bay Area seem to have 3D printing services for free — this might be an alternative for a one-off, while costing you nothing!

Shapeways have been around for ages, and I've always been satisfied with all their options.

https://www.shapeways.com/

The lowest price I can see when I upload my stl is $150, which is quite a difference from $30. Maybe I'm doing something wrong.

Are you willing to share the stl/general geographic area? I might be willing to print & ship. There's also https://old.reddit.com/r/3Dprintmything/ if all else fails.

I appreciate the offer but I already have it and don't need another right now (the onshape project is also linked if you're interested)

Thanks for the subreddit link though, it could definitely be useful in the future.

Thanks for the well annotated article. There are a lot of useful links here.

E-Ink with rust? It should not even contain iron

I thought e-ink used magnetically charged pixels, which would necessitate some ferrous materials.

But it looks like this was just an old rumor? https://www.mobileread.com/forums/showthread.php?t=14152

I want to do something like this. Should I get the esp32 or go with an Arduino/Raspberry Pico?

Also, for the e-ink screen, is there anything I should watch out for? Do I need it without PCB or with?

I want to order the pieces now and do something with Rust, but I wanna make sure I don't order something wrong. Any pointers would greatly be appreciated!

Are there any projects that make use of those e-ink price tags that seem to be ubiquitous and maybe cheap(er)? Or are they locked to prevent their use for other applications? Not sure if there's a good source for those e-ink price tags on a one-off basis that's down in the low double-digit pricing.

What is the Rust used for here? Do you manually write x,y pixels to these devices?

Can you use another program to rasterize a two tone bitmap image with the appropriate dimensions and then pass it to the display controller without needing to write any software?

Rust runs on the esp32 to send the data to the display, and is used on the server side to generate the image that is then served up to the esp32 to send to the display.

There is minimal software on the e-ink display side… it connects to wifi, fetches the image, and sends it to the display.

I've been wanting to build a 32 inch e-Ink thing on my wall, but the price is prohibitive. Anyone know of a cheaper source for 32-inch e-Ink displays?

There are projects that use old Kindles for such things. Anyone know of one that uses old Nooks?

(I could Google; more fun to discuss it here.)

How accurate is the weather.gov forecast? Compared to other regular consumer apps like weather.com or wunderground.com.

I always assumed those sites get their data from weather.gov or something similar.

Also, how does weather.gov compare to OpenWeatherMap.com?

I'm starting one of these "weather on an e-ink display" projects, and wondering which API to use.

It seems accurate enough at least to pick out clothes for the day. The precipitation forecast sometimes is a bit overzealous later out in the week but seems pretty accurate for the next 24 hours or so.

I'm a simple man. I see Rust, I Sage.

Awesome. Whelp, purchased the e-ink display, that looks nice.

I am also a simple man, I see a trend on HN and I join in.

I'm a simple man, I see 'but with Rust' and I reach for WD-40.

Or citric acid, depending on what is rusty.

Iron acetate has a very satisfying not-quite-gray color, so I favor vinegar.

its for recruiters and hiring managers

I'm a slightly less simple man, I reach for evaporust.

Reply on news.ycombinator.com