Some notes about my E-Ink studies.<p>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).<p>2. E-Ink is very slow especially at this price range. Static images are fine, but don't expect animations.<p>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.<p>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.<p>5. Most E-ink screens seem to be some kind of SPI protocol (4 wire). This is very similar to mini-LCD screens.<p>---------<p>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.<p>LCD might be more suitable for beginners. But e-ink is very cool and awesome.
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".<p>I have two of the adafruit variety and it works fine with circuitpython and all that.<p>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.<p>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.<p>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'.
Not sure if they're still available, but I have a handful of "Badgy's" along the same lines:<p><a href="https://www.tindie.com/products/sqfmi/badgy-iot-badge/" rel="nofollow">https://www.tindie.com/products/sqfmi/badgy-iot-badge/</a>
Another good starting point for an e-ink badge is <a href="https://shop.m5stack.com/products/m5paper-esp32-development-kit-v1-1-960x540-4-7-eink-display-235-ppi?variant=39966887903404" rel="nofollow">https://shop.m5stack.com/products/m5paper-esp32-development-...</a><p>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.<p>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.
MiP aka Memory in Pixel is a great alternative to eink as well, well epaper, since to buy eink you'll be paying £££.<p>MiP supports animations/fast screen changes as well, but consumes a small amount of idle power vs epaper/eink none. For a badge I think this is acceptable, but it's also so, so hard to find displays as I think only Sharp makes them.<p>Looked into it a lot after owning a Pebble Time Round. I hate Apple for making consumers want a bright oled screen on a watch as the only option; sure, I charge my phone overnight & watch while I shower (bc I want the sleep tracking) but if I'm out and about/on holiday and my phone dies, I'd appreciate my watch still functioning as a fucking watch past the end of the day.<p>Plus smart watches look so much nicer when the screen is on all the time. To get my galaxy watch to last into the next day I run with the screen off, only wake on button press.
Cool little project, great gift for in-person team meetings!<p>Don't have much more to say except it's nice to see this kind of creativity still around in a world where everything has to sit on our phone and be served remotely from some megacorp's cloud.
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.<p>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.
Isnt badger an old news by now? I had mine for quite time:
<a href="https://twitter.com/piropro/status/1505054493305671681" rel="nofollow">https://twitter.com/piropro/status/1505054493305671681</a>