e-ink is so much fun, especially when combined with ESP32 or BTLE boards. I currently have 4 around my house displaying book quotes that I've highlighted in KOReader and they bring me joy each time I see them. They are simple and do one thing very well.
I just got and setup a BTLE e-ink driver the other day and according to my calculations it will last _years_ on a single charge (2000mAh) even with multiple refreshes per day (crazy compared to the Wifi ones). Year+ lifetime completely changes the calculus for where to put these IMHO.
I'm considering designing a multiple-screen "art" piece to hang on my wall and playing around with various ideas (on both content and design).
LLMs + 3D Printer + e-ink is my new favorite hobby.
Thanks for speaking to the battery question; I'm very interested in how to run this kind of thing (the display portion at least) cordlessly too, especially when lipo pouches in that range are so dirt cheap.
I might be misunderstanding your comment but the display is run/powered by the board so all you need to do is provide power to the board. For e-ink it uses no power to "hold" an image, only to write/refresh (sorry if I'm telling you something you already know!).
So reiterate, with a 2000mAh lipo battery I should be able to drive the board _and_ the screen for over 3 years if I only refresh it at most once every 4 hours (with "push" capabilities, I don't have to deep-sleep the board to get that battery life). At least, that's what the calculator says, I _just_ got my hardware to play with and so I can't speak from experience. Unfortunately my board is not charging the battery so I need to get a replacement which will probably take a week or two to get here.
Yeah no we're aligned; I have some raspis that I'm interested in doing long term battery stuff with (remote sensing and the like) and it definitely does seem like connectivity is the huge killer, like even if you wake up only periodically to take a reading or update an epaper display, the cost in battery just to negotiate a wifi connection and do tcpip and http things is awful.
Years on a wall mounted eink screen sounds super interesting. What are you using for the power delivery/battery side of that setup?
Here are the parts I bought, I'm still getting it all setup (I have my pictures displaying, working on designing the 3D printed case now, and testing it all) but according to OpenDisplay's calculator [0] I can expect 3.4 years if I refresh the screen once every 4 hours (and currently I'm doing closer to once a day to mimic my ESP32s which need deep sleep and once-a-day refresh to get even month/months of battery on a charge).
Screen: 7.5" Monochrome eInk / ePaper Display with 800x480 Pixels (https://www.seeedstudio.com/7-5-Monochrome-ePaper-Display-wi...)
BTLE board: XIAO ePaper Display Board(nRF52840) - EN05 (https://www.seeedstudio.com/XIAO-ePaper-Display-Board-nRF528...)
Battery: 3.7V 2000mAh - (https://www.amazon.com/dp/B0FR9GH966)
Picture of it all assembled (no case yet): https://cs.joshstrange.com/zJFvGGPB
The image rendered to the screen is coming from a little service I wrote that renders a book quote it pulls from BookOrbit which syncs with KOReader (annotations, progress, etc). My plan is to set up one of these one each bookshelf/series rotating quotes I highlighted from the series.
Here are 2 ESP32-based screens I have, the one on the left is a an all-in-one [1] and the one on the right I printed the case from the TRMNL DIY kit from SeeedStudio [2]: https://cs.joshstrange.com/knk4Ns2h
Right now only the BTLE one is running OpenDisplay (the other two are semi-managed by HomeAssistant ESPHome) and all the devices are in HA for controlling them, though the ESP32's all deep-sleep for saving battery so I can can't "push" stuff to them like I can the BTLE one.
[0] https://opendisplay.org/index.html#battery
[1] https://www.seeedstudio.com/reTerminal-E1001-p-6534.html
[2] https://www.seeedstudio.com/TRMNL-7-5-Inch-OG-DIY-Kit-p-6481...
If I want a wifi e-ink connected display - curious what would you recommend. I want an e-ink display - that I can use as a sign/display board with wifi connectivity and remote administration.
If you want a simple e-ink wifi screen I'd point you at the reTerminal e1001 [0] if that size works for you. It's the easiest to get started with. You can either keep it on power or use the deep sleep to get more from the battery. It really comes down to how often you want to update it.
The BTLE boards have just crazy higher battery time with no need for deep sleep which is why I'm moving in that direction.
~7.5" is the size I've been buying so far, the larger e-ink screens get pricey but I can't wait for a calendar-sized one to come down in price such that I can frame it and hang it on the wall. Lastly I'd avoid the color e-ink screens unless you know you need color, won't need to refresh it often, and it's not in your eye line. Color refreshes take way longer (~30s in my experience for a 5-6 color screen) and the flashing it has to do is obnoxious. Monocolor displays take <2s normally and a single flash. I got a color screen first because "why not?" and I got color, but the refresh was too annoying so now it refreshes once a day in a place that I'm not when it refreshes so I don't have to see it.
I also recommend you check out OpenDisplay for what you will run on the device: https://opendisplay.org/index.html
[0] https://www.seeedstudio.com/reTerminal-E1001-p-6534.html
When it does run out, are you able to replace the battery? Or is it something way more painful than that?
It's a rechargeable battery, I just plug the board in (USB-C) and it charges the battery.