[HN Gopher] The E-Ink Badge
       ___________________________________________________________________
        
       The E-Ink Badge
        
       Author : nate
       Score  : 251 points
       Date   : 2023-02-28 16:56 UTC (6 hours ago)
        
 (HTM) web link (census.dev)
 (TXT) w3m dump (census.dev)
        
       | mrinfinite wrote:
       | I love my Dasung 253 paperlike!
        
       | xenon7 wrote:
       | I honestly wasn't expecting the device to use coin cells, but I'm
       | glad that it does. Not everything needs to be rechargeable.
        
         | oneearedrabbit wrote:
         | I built/assembled them. I carried out some informal experiments
         | and found that it requires roughly one million full screen
         | refreshes on two coin cells to completely drain them.
         | Furthermore, given that Badger operates on an RP2040 and a
         | battery holder comes with a toggle, it is astonishingly durable
         | device. It is like a smoke detector, which can operate for a
         | decade straight on a single battery.
        
           | dragontamer wrote:
           | Note: CR2032 is awesome and all, but be careful about
           | extrapolating like this out to decade+ timeframes.
           | 
           | CR2032 only has 235mA-hrs of life down to 2V. x2 and that's
           | only 470mA-hrs and 2V probably browns-out the circuit (so...
           | 470mA is already a stretch. You'll probably get less than
           | that on practice).
           | 
           | Over 10 Years, that's 5uA of power usage on the average.
           | 
           | ----------
           | 
           | IIRC, an aluminum capacitor has ~15 uA of leakage current,
           | and Tantalum is ~1uA of leakage current. So Aluminum caps are
           | already disqualified, and Tantalum capacitor leakage-current
           | already uses 20% of your power budget. Given the "Burstiness"
           | of this workload, I know that these capacitors need to exist
           | somewhere.
           | 
           | You probably can get a year out of this in practice. To get
           | better than that, you'll need to spend an incredible amount
           | of energy on finding every 1uA "leak" and plugging the leak.
           | 
           | And its crazy how many things leak 1uA. Not only capacitors
           | leak 1uA, but so do MOSFETs, diodes (reverse bias currents,
           | especially in schottky diodes)... diode-protected MOSFETs (oh
           | no, twice the leakage!).
        
             | oneearedrabbit wrote:
             | After I completed the project, I made a somewhat
             | lighthearted personal vow to try to design a custom PCB
             | next time I fall down the rabbit hole of hardware
             | tinkering. I suspect, these days it is a commodity skills,
             | and curious if you happen to have any suggestions or
             | articles that could serve as a starting point?
        
               | dragontamer wrote:
               | PCBs are a dark art, and I focus on lower-speed (below 30
               | MHz) to try and avoid any issues.
               | 
               | I know that the faster the PCB is, the more issues you
               | get. Above a certain frequency, inductors look like
               | capacitors, capacitors look like inductors, and PCB-
               | traces look like transmission lines with reflections and
               | other such nonsense. Staying at a slower speed helps
               | negate these issues.
               | 
               | Most application notes, be it from STMicro (for STM32) or
               | Microchip, or really any other microcontroller
               | manufacturerer, will have recommended hardware designs +
               | their thought process fully documented.
               | 
               | Start there. Here's Microchip's ATMega328 hardware design
               | notes: https://ww1.microchip.com/downloads/en/Appnotes/AN
               | 2519-AVR-M...
               | 
               | STM32F4: https://www.st.com/resource/en/application_note/
               | an4488-getti...
               | 
               | ---------------
               | 
               | Study up on the "reference designs". For ATMega328p,
               | that's Arduino Uno. For more recent AVR chips (such as
               | AVR DD), that's "AVR DD Curiosity Nano". (See schematics
               | here: https://www.microchip.com/en-us/development-
               | tool/EV72Y42A)
        
               | stavros wrote:
               | The sibling comment is too specialized, I feel. It
               | depends on what you want to do. If you just want to
               | connect a few components together, you can learn the
               | required skills in a day, watch some KiCAD videos.
               | 
               | I made a sensor board the other day (I'm just printing
               | the case for it now), and it was very enjoyable, and even
               | came assembled for $1.7 per board:
               | 
               | https://gitlab.com/stavros/sensor-board
               | 
               | Feel free to email me if you have any questions or just
               | want to chat.
               | 
               | Also, I don't think I've ever wanted something in my life
               | more than this badge thing.
        
               | dragontamer wrote:
               | > The sibling comment is too specialized, I feel. It
               | depends on what you want to do. If you just want to
               | connect a few components together, you can learn the
               | required skills in a day, watch some KiCAD videos.
               | 
               | That's fair.
               | 
               | Lets put it this way: if your circuit works on a
               | breadboard, you don't need to know anything about PCB
               | design. The PCB will pretty much always be better than
               | the breadboard.
               | 
               | Things get troublesome as you enter mixed-signal (analog
               | + digital), or high-frequency.
        
               | stavros wrote:
               | Agreed, but you still need to know a ton of things that
               | seem hard when you haven't done them before. Even
               | exporting the Gerbers, or the BOM for assembly, or any of
               | those things seemed too hard to me before I did it for
               | the first time, so I don't want to underestimate people
               | asking "I want to connect a few components into a custom
               | PCB, how do I do it?".
        
           | nickthegreek wrote:
           | That has to cut down on the thickness as well since the
           | Badger 2040 is designed to take AAA. Wish there was a side
           | shot to see your total thickness.
        
             | oneearedrabbit wrote:
             | Exactly! The device is approximately 12mm thick. I will
             | upload a side shot shortly. I appreciate you bringing this
             | up, it's an excellent point! To be honest, it is still a
             | bit thicker than I had initially hoped for; however, when I
             | weighed my options - solder 26 devices by hand vs use pre-
             | made components -- the decision was much more clear.
        
             | outworlder wrote:
             | > That has to cut down on the thickness as well since the
             | Badger 2040 is designed to take AAA.
             | 
             | Would it be ok with the lower voltage of NIMH
             | rechargeables? I really dislike primary batteries.
             | 
             | Edit: found the answer.
             | 
             | > 2x AAA rechargeable (NiMH) batteries only puts out 2.4V
             | which is, strictly speaking, not enough for Badger.
             | However, in our tests it keeps on truckin' down to an input
             | voltage of 2.05V (without the LED), so if you want to use
             | rechargeable batteries that should be fine.
        
             | dragontamer wrote:
             | AAAA is popular and as cost-effective as CR2032 (aka: bad
             | value, but less-bad value than most other batteries of this
             | size). Note that CR2032 is toxic, so AAAA is somewhat
             | preferred.
             | 
             | AAA and AA have much more energy-per-dollar. I mean, so
             | does lead-acid but I guess that's too big lol.
             | 
             | ---------
             | 
             | Specialty batteries, like CR123A, seem to fit the bill for
             | this size much better. But those are so, so much more
             | expensive. I feel like the only two cells worth really
             | considering are AAAA and CR2032, despite their
             | deficiencies.
        
       | VLM wrote:
       | Really the "hidden story" is the pimoroni board is like "ten
       | bucks" whereas two years ago the exact same application was
       | available from Adafruit for "fifty bucks".
       | 
       | I have two of the adafruit variety and it works fine with
       | circuitpython and all that.
       | 
       | Someday the "wifi connected eink screen" will drop to maybe five
       | dollars and that will be interesting in the market, open up some
       | product ideas.
       | 
       | The adafruit product uses most of its power sleeping and
       | occasionally waking up to check the wifi in the apps I played
       | with, the screen itself doesn't use much power. I suppose it
       | depends how often you want to refresh.
       | 
       | An example of interesting/weird apps for this technology is we're
       | already at the point where its probably cheaper if you want a
       | remote thermometer displaying on your wall to skip owning an
       | actual thermometer and just display some web API of the current
       | airport temperature or whatever. I wouldn't invest in consumer
       | grade high resolution temperature sensors, you can replace all of
       | that with a little wifi traffic right now and it's only going to
       | get 'worse'.
        
         | Psychlist wrote:
         | > skip owning an actual thermometer
         | 
         | Doesn't that rely on you living next to someone else's
         | thermometer that's published? My not very accurate setup gives
         | me more than a degree just down my property line (~30m) largely
         | because one end is next to a road and the other on lawn
         | surrounded by trees. Albeit neither are proper meteorological
         | stations so accuracy in that sense isn't even an option.
         | 
         | I publish a few readings but have never really looked into the
         | exact accuracy of the https://www.uradmonitor.com/ sensors. My
         | actions in response are pretty coarse so it doesn't matter a
         | huge amount... PM10 goes over 300 and I close the doors and
         | windows sort of thing.
        
         | karmanyaahm wrote:
         | Tangent: My gas station replaced grade-selection buttons and
         | rate/volume/price LCDs with one huge (20") touchscreen.
         | Unfortunately because of the distance, it's brighter than the
         | overhead lights at night. No one thought to add a little
         | brightness sensor to the several thousand dollar machine.
        
       | nielsbot wrote:
       | Cool... but I really wish it didn't have bezels!
        
       | abraxas wrote:
       | This century's pocket protector!
        
       | GrumpyNl wrote:
       | Am i as a visitor, supposed to push the buttons on your badge?
        
       | brk wrote:
       | Not sure if they're still available, but I have a handful of
       | "Badgy's" along the same lines:
       | 
       | https://www.tindie.com/products/sqfmi/badgy-iot-badge/
        
         | masklinn wrote:
         | Apparently out of stock.
         | 
         | The linked badger 2040
         | (https://shop.pimoroni.com/products/badger-2040) is half the
         | price and apparently in stock. TFA is a 3D printed case around
         | that, and custom software for the badge. It's also powered by a
         | more capable dual-core M0+, however wifi is lost.
        
       | sxp wrote:
       | Another good starting point for an e-ink badge is
       | https://shop.m5stack.com/products/m5paper-esp32-development-...
       | 
       | It won't work as a badge out of the box, but if you know how to
       | program an ESP32, it's easy to get it to use the demo libraries
       | to load a JPG. It also has a touchscreen and 3 physical buttons
       | for basic interactivity.
       | 
       | It's $85, so it's pricy for being used just as a badge, but it's
       | a cool gadget that I use for a desktop display.
        
       | crote wrote:
       | The only thing which would make this even cooler would be
       | RP2040-controlled NFC. I wonder how hard that would be to add?
        
         | oneearedrabbit wrote:
         | Badger comes with a built-in Qwiic / STEMMA QC connector. I
         | believe it should work out of the box with Adafruit ST25DV16K
         | I2C RFID: https://www.adafruit.com/product/4701
        
       | sadpolishdev wrote:
       | Isnt badger an old news by now? I had mine for quite time:
       | https://twitter.com/piropro/status/1505054493305671681
        
       | IronWolve wrote:
       | I thought e-ink was fad, but finally broke down and bought an
       | e-ink ebook reader, the battery life that lasts a month is
       | amazing.
        
         | malfist wrote:
         | I use my kindle all the time and I totally forget about
         | charging it. Then suddenly it tells me it's low on battery and
         | I remember "oh yeah, I've not charged this in like 3 months"
         | 
         | What other modern battery device has that many
         | interactions/uses without needing near daily recharges? It's
         | like magic
        
         | IshKebab wrote:
         | Why did you think it was a fad? Just curious. Had you ever seen
         | one in real life?
        
         | knodi123 wrote:
         | And I try to convince my family about it, but just _cannot_ get
         | it through to them that  "kindle the tablet" and "kindle the
         | ebook reader" are entirely unrelated products. What a terrible
         | bit of branding.
        
         | stronglikedan wrote:
         | I will always take the opportunity to read without a backlight.
         | It's a hugely noticeable difference on the eyes for me. I'm
         | just glad I don't have to print out thousands of sheets of
         | paper just to read documents comfortably any more.
        
           | IronWolve wrote:
           | I was reading on a normal android tablet. When I saw a sale
           | on a kids bundle for 99 bux, decided to pull the trigger.
           | Been my night time reader for months when going to sleep.
           | It's amazing how easy on the eyes it is. I just read until I
           | start to nod off.
        
       | schwartzworld wrote:
       | I bought a badger2040 recently. I mainly wanted it for the ebook
       | feature. A pocket-sized eInk device could make reading throughout
       | the day so easy. I used to always have a paper book in my back
       | pocket before phones.
       | 
       | Anyway, it's a great device with one small caveat. None of the
       | GPIO pins are exposed, the only IO is buttons, usbc or a
       | QT/Stemma connector. This would all be fine by me, except that
       | there is only about 1mg of free space on the device. Doing any
       | serious reading would require me to use external memory and
       | without GPIO I can't do that. Making a few pins accessible would
       | make attaching an SD card completely trivial.
        
         | karmanyaahm wrote:
         | Because the RP2040 is so dynamic, the QT/Stemma connector _is_
         | two GPIO pins, even thought it can do I2C or SPI.
        
           | schwartzworld wrote:
           | Are you saying interfacing with an SD card should be possible
           | using only 2 pins?
           | 
           | https://content.instructables.com/FJT/PT8T/KROXES4A/FJTPT8TK.
           | ..
        
         | whiskers wrote:
         | If you look at the back of the badger you'll see that we put a
         | set of pads to solder to for GPIO!
         | 
         | It also has a "Qw/ST" connector (STEMMA + Qwiic) that exposes
         | an I2C bus so is ideal for adding sensors, or you could bash on
         | an IO expander for a heap more pins!
        
           | schwartzworld wrote:
           | Sensors don't fit my use case, but I can't believe I didn't
           | notice those pads. I'll see if I can make them work.
           | 
           | I don't believe that SD cards can be interfaced with over
           | i2c.
           | 
           | If I were you guys I would consider having a built in SD
           | reader in version 2.0, as it would add a lot of value.
        
         | adolph wrote:
         | You might be interested in the Serial Wombat which can expose
         | gpio as as I2C, for which it has pads on the back.
         | https://www.serialwombat.com/
        
       | ajsnigrutin wrote:
       | Hey! What's wrong with csv files?!
        
       | iwebdevfromhome wrote:
       | Anyone else using this for cool ideas ? Please share!
        
         | gambiting wrote:
         | Yes, I just got my Badger W few days ago and I'm pairing it
         | with a temperature/humidity/CO2 sensor - I designed and 3D
         | printed a bracket for it, I'm going to mount it on a wall in my
         | kitchen. It's also going to show brief weather forecast and the
         | current price of my energy tariff(it changes daily).
         | 
         | That's what it looks like(just assembled it today so I haven't
         | written code for it yet):
         | https://photos.app.goo.gl/NjdisB8PbfFiGgkk9
        
         | toyg wrote:
         | I have a badger2040, looping through a few different screens -
         | one with a QR code pointing to my linkedin. The lack of
         | integrated battery is annoying though - either you stick a
         | potentially hazardous one to the back, or you're carrying
         | around a bulky AAA enclosure.
        
         | JKCalhoun wrote:
         | E-ink in general?
         | 
         | I did a desk calendar that looks like an old Mac:
         | https://github.com/EngineersNeedArt/SystemSix
        
           | samizdis wrote:
           | My favourite e-ink application was in the Yotaphone II [1]
           | some years ago, but sadly discontinued. I had one sent from
           | the UK to Australia, where I was working for a few years.
           | Reading books, docs or emails via the e-ink screen was a joy
           | (no probs with bright sunshine), as was calling up your
           | airline pass on the screen and turning off the phone, because
           | the image on the back was retained. Even writing emails/docs
           | was fine for me, despite the e-ink lag. I needed to charge it
           | only every other day, and that still left plenty of margin.
           | Best phone I ever had.
           | 
           | [1] https://www.gsmarena.com/yota_yotaphone_2-6959.php
        
           | sho_hn wrote:
           | Very cool!
           | 
           | I linked my framed e-ink newspaper build elsewhere in the
           | thread, here's to e-ink hacking :)
        
           | sokoloff wrote:
           | I love the "it's trash day" being represented as a full trash
           | can on the desktop!
        
         | bobbiechen wrote:
         | At the beginning of 2020, I worked on a project to create a
         | status indicator for real life, to help people in the office
         | communicate whether it's okay to interrupt them or not. We
         | ended up using a Pimoroni Inky with Raspberry Pi to auto-sync
         | calendar/Slack status - easy to work with and reasonably
         | pretty.
         | 
         | Of course, we didn't have a chance to deploy it before the
         | pandemic hit, but someday I'll come back to it...
         | 
         | Here's my teammate's writeup of the project, including
         | photos/video: https://www.timmychiu.com/dash
        
       | dragontamer wrote:
       | Some notes about my E-Ink studies.
       | 
       | 1. E-ink requires a number of external components, even with
       | their "chip on glass". In particular, E-ink requires a high
       | voltage to change and charge the ink. I've seen inductors on most
       | of these reference designs (ie: suggesting a boost converters of
       | some kind).
       | 
       | 2. E-Ink is very slow especially at this price range. Static
       | images are fine, but don't expect animations.
       | 
       | 3. E-ink protocols take a "temperature". In my cases, I've just
       | been hard coding it to 25C / Room temperature, but this suggests
       | that low-temperatures or high-temperatures may change the
       | behavior of the screen.
       | 
       | 4. E-ink is very "bursty" with power, using more power than LCD
       | when changing images, but then zero power for most of its life.
       | Be sure to think carefully about the current associated with this
       | burst, especially if you're using small CR2032 coin cells (which
       | have ~10 to ~100 ohms of internal resistance). A ~100mA draw on
       | the charge inductor isn't out of the question (at 10-ohms, that's
       | a voltage drop of 1V, which probably browns-out the RP2040). A
       | slow-start circuit could solve this but you'd need to consider
       | the longer charge times. Another method is to have 2x CR2032
       | cells in parallel, which lowers IR (parallel resistors lower
       | resitance). I'd be most interested in studying the power-network
       | of this design, I bet there's some interesting things going on
       | here.
       | 
       | 5. Most E-ink screens seem to be some kind of SPI protocol (4
       | wire). This is very similar to mini-LCD screens.
       | 
       | ---------
       | 
       | LCD screens use more power, but get you color, more resolution,
       | animation and seem to be cheaper still. Furthermore, LCD requires
       | fewer external components (maybe a charge-pump set of capacitors,
       | but some LCD screens don't even need that). Note that
       | color/resolution/animation all costs processor power / storage /
       | RAM, so be careful what you wish for.
       | 
       | LCD might be more suitable for beginners. But e-ink is very cool
       | and awesome.
        
         | samstave wrote:
         | First ; Gosh I wish I had the knowledge you have on electric
         | transfrerence/resistance==ohms/volts
         | 
         | But given that coin discs input/output are heat-dependent based
         | on your comment, and no knowledge, would it not be sound to
         | place CR coin batts in a baffle of graphene-aero-gel which
         | could be just mm thicc and shield them from said temp
         | inflections? This would greatly increases life, and can be
         | moulded and produced en-mass with little effort and minimal
         | cost (especially if you encase batteries used in space flight
         | etc - and one may use the non-conductive format to use
         | aerogells as an extremely light and thin insulating layer for
         | many a thing.
         | 
         | Imagine the ability to 'spray' an AeroGel sealant onto a
         | component which is heat sensitive to its accuracy...
        
           | dragontamer wrote:
           | Its not hard. But you often need someone to "initiate" you
           | with the correct documents.
           | 
           | Try reading these: https://data.energizer.com/pdfs/cr2032.pdf
           | 
           | https://data.energizer.com/pdfs/lithiumcoin_appman.pdf
           | 
           | Hopefully that answers any questions you have. You might need
           | to research some other bits of knowledge to build up your
           | base EE skillset, but once you're able to read those
           | documents + understand them, I think you'll be in a good
           | spot.
        
         | sho_hn wrote:
         | I've recently built a little "automatic newspaper" home deco
         | piece using a 13.3" e-ink display, mainly as an excuse to try
         | out Rust on an ESP32:
         | 
         | https://imgur.com/a/PqkhdGd (edit: corrected link to album with
         | finished pics)
         | 
         | This is using an IT8951 EPD controller I wrote a little Rust
         | driver for, which indeed talks SPI, although its SPI frontend
         | is really a quirky/leaky abstraction over an I80 interface so
         | you have to e.g. do chip select using I80 semantics and send
         | preambles and such. Still, pretty breezy overall.
         | 
         | Can confirm the power draw is of course "bursty" during the
         | update. Also, yes, e-ink refresh times get slower in colder
         | temps. e-ink refresh also works poorly in direct sunlight. The
         | displays can also "dry out" from it and it can cause artifacts.
         | But the envelope for normal operation is overall fairly good,
         | certainly for home/indoor use.
         | 
         | There's a fair amount of manufacturing tolerance and during
         | testing manufacturers will usually record preferred drive
         | voltages for the individual unit, etc. It's quite important to
         | configure software to make use this information for optimal
         | performance.
         | 
         | I'm hoping it will run for about a year without recharging from
         | that little 1100 mAh LiPo pouch at one update a day (the
         | newspaper is rendered on a common home server RasPi using
         | LuaLaTeX+Ghostscript and then retrieved over Wifi), having
         | taken self-discharge into account.
         | 
         | For more du-jour hype points I'm considering using OpenAI on
         | the backend to summarize articles down to size to fit the
         | layout! Or make it do style transfer to "1870 newspaper".
        
           | bostonvaulter2 wrote:
           | That looks great! How much was the e-ink screen itself?
        
             | sho_hn wrote:
             | About $400 + shipping from Waveshare.
        
           | oneearedrabbit wrote:
           | I love it! On a somewhat related note, I've been working on a
           | tiny Forth interpreter lately, and I think the e-ink device
           | it could be an interesting choice to explore and test it on
           | as a dedicated computational environment. Inkplate looks very
           | appealing: https://soldered.com/product/inkplate-6plus-e-
           | paper-display-...
           | 
           | You might want to check out Kagi to summarize articles:
           | https://labs.kagi.com/ai/sum. It does the heavy lifting of
           | producing nice outputs for you.
        
           | renewiltord wrote:
           | What's the screen? Where did you get it from?
           | 
           | It looks really cool!
        
             | sho_hn wrote:
             | Thanks!
             | 
             | It's this product, which is built around a ED133UT2 panel
             | by E Ink: https://www.waveshare.com/product/displays/e-pape
             | r/epaper-1/...
             | 
             | You can find this unit and other IT8951-based driver boards
             | for it on a few different places/in different catalogs but
             | Waveshare's easy and the price seems OK.
             | 
             | The ED133UT2 is a Carta 1200 display. The latest Carta gen
             | is the 1250, but AIUI it's only relevant for color displays
             | with the change being a thinner film that allow plastic
             | color filters to be closer to the ink to improve contrast.
             | I think the current greyscale 13.3" offered by E Ink's
             | direct shop for $449 sans driver is still a 1200 - at least
             | many vendors list VB3300-NCB as just an alternate name for
             | the ED133UT2. The Carta range of displays are well-known
             | from Amazon's Kindle and many other reader products, so my
             | newspaper is basically a big honking DIY Kindle.
             | 
             | They also offer a 10.3" panel with even higher resolution
             | for half the price of the 13.3" that's supported by the
             | same controller and should be fantastic for all sorts of
             | home dashboards.
        
               | anoncow wrote:
               | I worked with 7.5 inch screen a few years ago for a
               | desktop Todo list, but the display faded overtime (1
               | year).
        
               | sho_hn wrote:
               | This seems to be pretty common with E Ink displays
               | unfortunately (you hear the same about many commercial
               | ebook readers). At least the larger ones are more or less
               | all from the same manufacturer (E Ink). I don't know if
               | there is binning going on and Amazon gets better batches
               | than Waveshare does ...
               | 
               | Direct sunlight can also be a big problem for this
               | display tech, so I'm intentionally hanging it on a wall
               | facing away from the most intense daytime sunlight I get.
               | 
               | Hope it survives at least a couple of years.
        
               | erksa wrote:
               | Thanks for the info!
               | 
               | I saw something like this a couple of years ago and
               | wanted to do it myself. However the cost was relatively
               | unattainable at the time, I'm glad to see it is getting
               | more affordable!
        
               | alexose wrote:
               | Shoutout to the EPDIY project, which supports the
               | ED133UT2 and is planning to support the 10.3" ES108FC1 in
               | a future revision!
               | 
               | https://github.com/vroland/epdiy
        
               | sho_hn wrote:
               | This is extremely cool!
               | 
               | While cobbling together my project I was really tempted
               | to go custom PCB with the ESP and the ITE controller on
               | one board. Looks like this eschews the seperate
               | controller entirely and instead uses ESP32 PSRAM for the
               | framebuffer and has the driving waveforms embedded in the
               | MCU firmware etc. Very neat, also one further level of
               | "go deeper", would love to try one!
        
           | stavros wrote:
           | This is great! Would you happen to have the code available
           | somewhere?
        
             | sho_hn wrote:
             | Not yet, sorry! It's still very fresh; I'll be releasing on
             | GitHub pretty soon after cleaning it up a little and
             | writing some documentation. When getting around to it I'll
             | remember your comment and drop you a line.
             | 
             | https://github.com/eikehein/hyelicht <- I get a little
             | obsessive with that when documenting/releasing DIY stuff
             | ... :-)
        
               | stavros wrote:
               | Wow, haha, that's extensive. However, I'd urge you to
               | release first and write docs later (or even release first
               | and make it work later). I'd get a lot more value from
               | code with no docs than no code at all!
        
               | sho_hn wrote:
               | I'll try to RERO!
        
         | bsder wrote:
         | > Another method is to have 2x CR2032 cells in parallel, which
         | lowers IR (parallel resistors lower resitance).
         | 
         | Don't do this. It will work for a short time, but this
         | basically just drains one of the CR2032 cells dead.
         | 
         | The issue is that lithium cells have very little discharge
         | slope, so by the time the two voltages equalize, one of the
         | cells is about to die.
         | 
         | This is in contrast to alkaline batteries which have quite a
         | bit of discharge slope, so the two batteries can equalize
         | voltage with most of their battery life still remaining.
        
         | tiedieconderoga wrote:
         | For very small stuff, OLED displays are another possible
         | alternative. Great contrast, and there's no backlight so you
         | don't spend power on the "off" pixels.
         | 
         | You could start with SSD1306 (monochrome, 3.3V) and SSD1331
         | (16-bit color, boosted voltage required). They speak I2C and
         | SPI, and have decent software support.
         | 
         | The cheap and cheerful ones are <=1" diagonally though, so you
         | need to step off the happy path to find badge-sized ones.
        
         | karmanyaahm wrote:
         | > small CR2032 coin cells (which have ~10 to ~100 ohms of
         | internal resistance). A ~100mA draw on the charge inductor
         | isn't out of the question (at 10-ohms, that's a voltage drop of
         | 1V, which probably browns-out the RP2040).
         | 
         | n=1, but I'm using a single CR2032 with a Badger 2040 (same as
         | OP) and a DS3231 in parallel and it works just fine down to
         | ~2.8 volts.
        
           | sho_hn wrote:
           | By the way, for the e-ink project I just linked in the other
           | comment I ended up discovering the RV-3028-C7 RTC module.
           | Idle power draw 45 nA at 3.3V instead of 110 mA for the
           | DS3231 for similar functionality and +-1 ppm accuracy with an
           | internally sealed oscillator. Awesome for battery-powered
           | stuff and cheaper at low qty on Digikey.
           | 
           | I hope more of those little DIY/maker breakout boards adopt
           | it. Pimoroni sells one. The one in my project is a free
           | sample dev board that Micro Crystal sent me on request -
           | which I guess is working out for them considering I just
           | shared their product with you all.
        
         | oneearedrabbit wrote:
         | Recently, I have come across some interesting developments in
         | the e-ink space. Although I haven't had the opportunity to test
         | DASUNG monitors myself, but I read positive reviews. It is
         | impressive, these monitors have extremely fast refresh rate.
         | Yes, they are pricy. I am intrigued if something has changed
         | technologically?
        
           | sho_hn wrote:
           | Your comment made me curious, but after looking at a teardown
           | blog the 13" Dasung Paperlike uses the same ED133UT2 panel by
           | E Ink as in my DIY newspaper project, which is a panel
           | originally released about 2016/2017.
           | 
           | That said getting good partial refresh performance out of a
           | panel like this requires a good controller and good code
           | (after having written a driver for one such controller
           | recently), and developers and product integrators have gotten
           | more refined at this. Refresh speed and display quality are
           | still a trade-off here though, expressed as different
           | waveforms when driving the same display.
        
         | roughly wrote:
         | Second the power draw on refresh - that surprised me for the
         | projects I was using it with. Especially if you're planning on
         | any kind of animation or dynamic display, it can eat your power
         | budget a whole lot faster than you were expecting.
        
         | Animats wrote:
         | > But e-ink is very cool and awesome.
         | 
         | E-ink should be, but it never seems to get there. Too low-
         | contrast and/or too expensive. It's been a Real Soon Now
         | technology for about two decades.
         | 
         | There was another persistent display technology - chomeric
         | displays. They came from a company called Chomerics, which was
         | acquired by Parker Hannefin, which dropped the product line.
         | Almost everything about those has disappeared from the Web,
         | except that the former factory is now a Superfund site.[1]
         | 
         | [1]
         | https://cumulis.epa.gov/supercpad/CurSites/csitinfo.cfm?id=0...
        
           | WillAdams wrote:
           | I've been using it since my previous job bought me a Sony
           | PRS-505 (a co-worker got an Amazon Kindle).
           | 
           | Works well, w/ great battery life, and it really has come
           | into its own w/ the new Kindle Scribe --- a large screen
           | e-ink device which works as an e-reader and has useful note-
           | taking and annotation capabilities (looking forward to seeing
           | what competitors do w/ it --- probably would have bought an
           | Onyx Tab Ultra if the Scribe hadn't been available).
           | 
           | I'd really like to see an affordable display suited to a
           | Raspberry Pi, ideally w/ touch.
        
           | amluto wrote:
           | I'm cautiously optimistic, because two decades is the
           | lifespan of a patent. E Ink the company has been a terrible
           | steward of the technology. May they lose their state-
           | sponsored monopoly and fade into irrelevance in peace.
        
             | fossuser wrote:
             | Unfortunately it's not that simple.
             | 
             | I talked to someone building related tech in the industry
             | and E-Ink the company has a stranglehold on suppliers and
             | leverages that to force compliance despite the patent
             | nearing expiration (blocking anyone else from getting
             | access to those suppliers).
             | 
             | The patent has allowed them to become entrenched and all
             | current suppliers to depend on them. This will be hard to
             | correct even with patent expiration.
             | 
             | I don't remember the specific details (unfortunately) and
             | it's second hand info, but I was disappointed to hear it
             | from someone more involved than I.
        
               | amluto wrote:
               | I wish the FTC would crack down harder on exclusivity
               | deals like this.
        
               | Animats wrote:
               | Why? E-Ink is a tiny niche in the display sector. Now,
               | if, say, only Apple had E-Ink phones, it would be a
               | monopoly issue.
        
               | amluto wrote:
               | E-Ink is apparently engaged in anti-competitive
               | practices. Why should it matter that the market in
               | question is small?
               | 
               | Lots of companies do this. Amazon demands exclusivity for
               | certain book sales, and they have contracts with sellers
               | that make it hard for other marketplaces to undercut
               | them. Qualcomm is famous for abusive practices. The list
               | goes on.
               | 
               | In general, IMO companies should be able to compete by
               | offering a superior product and/or a superior price point
               | and/or a superior experience. They should not be able to
               | compete by getting in each others' way.
        
           | outworlder wrote:
           | Expensive yes, but low contrast? Doesn't it have the opposite
           | problem?
        
           | zamnos wrote:
           | Maybe for you. But the first Kindle came out in 2007, and
           | Amazon has sold tens of millions of them. The latest, the
           | Kindle Scribe, even allows users to write in books with a
           | pen.
        
             | CrazyStat wrote:
             | I have an e-ink tablet (Boox Tab X), which is like a Kindle
             | Scribe except it's also a (more or less) full featured
             | Android tablet.
             | 
             | I have a very nice setup with Zotero, where I can sync
             | papers I want to read to the tablet (running Zoo for
             | Zotero), read and mark them up, and then sync the marked up
             | version back to my computer.
        
           | bitL wrote:
           | I use Onyx A4 reader and it has completely replaced paper for
           | me. Making notes directly to PDFs while I read them is
           | fantastic. And it saves my eyes. The only drawback is the
           | price (around $1k). I am not watching videos on it though.
        
           | dragontamer wrote:
           | Sharp's Memory LCD technology (made famous by Pebble
           | Smartwatch) was pretty good IMO.
           | 
           | They still sell those on Digikey:
           | https://sharpdevices.com/memory-lcd/
           | 
           | https://www.digikey.com/en/products/detail/sharp-
           | microelectr...
           | 
           | This is an LCD screen with active-power measured in micro-
           | amps. This means that memory-lcd is more power-efficient than
           | e-ink even if it updates once every 5 minutes. (though the
           | less you update, the better e-ink gets).
        
             | AshamedCaptain wrote:
             | People don't realize that e-ink and related technologies
             | simply _suck_, and rather make up crazy conspiracy theories
             | about eInk for some reason sabotaging their own product.
             | Consumers don't want eInk. Consumers cannot distinguish
             | eInk from LCD. Most companies that have made non-LCD based
             | products are simply out-sold by LCD products and go
             | bankrupt. I could probably name half-a-dozen non-LCD
             | reflective technologies which are _dead_ today without even
             | checking Wikipedia, like Gyricon, Mirasol, the stuff the
             | OLPC used, Flepia, etc. All of them dead or niche.
             | 
             | Even price displays are usually LCDs, with only a minority
             | being eInk, but as you can see here, even casual hackers
             | have a hard time distinguishing between them.
             | 
             | Th small displays they put on smartcards (showing a 2FA or
             | the like) are also LCDs, and even with a practically
             | minuscule battery they last for a decade, and that's
             | refreshing itself once per hour... there's absolutely
             | nothing that would improve with eInk, save for perhaps if
             | you wear polarizing glasses...
        
           | Pet_Ant wrote:
           | > E-ink should be, but it never seems to get there. T
           | 
           | Every price tag at my local grocery store is eInk. Like there
           | must be thousands. I'm guessing there are updated by wifi. I
           | mean that is pretty damn good use and the refresh rate means
           | you saw real energy over LCD.
           | 
           | https://www.mrbdvr.com/products/e-ink-price-tag-99
        
             | donio wrote:
             | If you wanted to make these cheap couldn't you have tag
             | contain nothing but the eink matrix and a connector and the
             | have all the electronics in the burner caddy?
        
             | trompetenaccoun wrote:
             | Funny you should bring this up, I just thought about it
             | today what a terrible development those electronic price
             | tags are from a consumer perspective. Because of course the
             | next step is constantly changing the prices based on
             | customer data telling them how to extract the maximum
             | amount of cash from shoppers. Which is what I noticed at
             | stores where they do have them, in extreme cases they
             | change the prices of some products multiple times a day.
        
               | joezydeco wrote:
               | Wait until they change price as you approach the shelf.
               | Maybe put that phone in airplane mode when you shop.
        
         | dmonitor wrote:
         | I can confirm that they start to act weird around high
         | temperatures. Just exposing it to the sun for a few minutes on
         | a hot day can make dots not transition correctly
        
         | frosted-flakes wrote:
         | One very widespread use of two-color (red and black) e-ink
         | screens is grocery store price labels. They're everywhere in
         | Canada, and they work great. Even the fine-print (price per
         | 100g) is clearly readable.
         | 
         | I don't know if they have batteries and wi-fi, or if they're
         | updated manually with NFC, but either way they can't be too
         | expensive if there are 5000+ in every store. They're a bit
         | smaller than the badges these guys made, but they might be a
         | lot cheaper and easier to work with.
        
           | dragontamer wrote:
           | > I don't know if they have batteries and wi-fi, or if
           | they're updated manually with NFC
           | 
           | Yes, yes, yes, and other methods. These are called
           | "Electronic Shelf Labels", and there's a whole slew of
           | competitors.
           | 
           | WiFi is very high power, so its "pull only twice a day" kinda
           | setup. You have a radio that only turns on twice a day to
           | contact the server. Zigbee is also a solution, though that
           | requires a Zigbee router (coordinator? I forget the
           | terminology). Much less power on Zigbee, but if you're
           | deploying hundreds/thousands of these ESLs, I think the
           | benefits of Zigbee low power outweigh the penalties.
           | 
           | NFC exists but I don't think I've ever seen them in person.
           | Probably too much effort since it'd require a human walking
           | around the store?
           | 
           | I've even seen ESLs that work off of infrared. You're
           | supposed to install IR LEDs all around the store, and they
           | can it all shelf-labels to update. IR receivers are the
           | lowest power, so this is the only way you can feasibly "push"
           | data to a shelf label. (Wifi and Zigbee are "pull only").
           | 
           | So some computer blasts the IR signal around the whole store,
           | which is enough information to transmit to change all the
           | prices apparently. Like a giant broadcast remote control.
        
             | philipphutterer wrote:
             | There was some information only recently on HN about
             | reversing those Electron Shelf Labels [0] that was quite
             | interesting, but your comment makes me wonder if you could
             | eavesdrop these wifi price updates in such stores. Also,
             | searching for that term on HN gives some other fun
             | projects.
             | 
             | [0] https://news.ycombinator.com/item?id=34738649
        
           | TheAdamist wrote:
           | Ive seen similar (maybe the same) red black eink screens at
           | best buy in the usa for pricing labels as well over the last
           | year, so they're not exclusive to north of the border. Far
           | fewer labels than a grocery store though.
        
           | jonathankoren wrote:
           | eInk price labels always make think about time of day
           | pricing, and even differential pricing based on computer
           | vision.
           | 
           | Sure, you can't do it today, but I'd be surprised if we don't
           | see it in 20 years.
        
         | Ballu wrote:
         | Could you recommend any good similar size as well as
         | functionality LCD for my personal project? Charging is not an
         | issue (short term use), minimal equipment and clarity at screen
         | are key requirements.
        
           | dragontamer wrote:
           | https://www.digikey.com/en/products/filter/lcd-oled-graphic
           | 
           | These are cheap enough that you can pretty much buy what you
           | want and sample them yourself.
           | 
           | I know there are other stores that have better prices. But
           | Digikey has a very good selection and has data-sheets for
           | most of their offerings.
           | 
           | ---------
           | 
           | I personally like the Sharp memory-lcd display. But your
           | milage may vary. Monochrome is fine for my uses
        
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