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Comment by gigel82 | Hacker News Reader

There are a lot of "electronic price tags" which are basically the same form factor as your trading cards, except they mass produce them (have nice plastic cases) and they usually include a 3-color eink (black-white-red or black-white-yellow) plus a wireless transmitter (usually proprietary protocol, but sometimes plain Bluetooth and/or NFC) for OTA updates and a 10-year battery (sometimes replaceable CR2032). Also, if you can grab them at $6 / piece, I imagine they're being produced for a lot less than that (random AliExpress link: https://www.aliexpress.us/item/3256803094207083.html).

If you're thinking of mass-production might be worth reaching out to one of those manufacturers; you can buy in bulk if nothing else (but I'm sure they'd be open to customizing it a bit - maybe some branding on the plastic molding and whatnot).

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Heh, the screens I use are exactly the ones contained in those products.

Huh, the battery lasts for ten years? I wonder how many refreshes you get for that. Maybe I should just be using those.....

I've worked in retail for an electronics store where we gradually changed over to those. They were from https://www.ses-imagotag.com/products/electronic-shelf-label... They even calimed to us 13 years batery life at an average of 1 refresh per day. They are pretty power efficient and we've had many devices that ran for years without an issue.

That's around 5000 refreshes, being a bit charitable. If I'm playing cards, I might see that in a few days, as I'm going to be doing tens or hundreds of refreshes a day, rather than one.

If the cards are always on a table / special playing surface, they could be wirelessly charged during play.

Some variants use NFC power to drive the display update, so no batteries!

I didn't realize NFC could deliver enough power for that. I'll look into it.

The demos I saw of this were slow, on the order of 10 seconds to get enough power through.

aha! So there is a catch. Still worth checking out.

If you could store that power in a capacitor it might be fine.

Basically, only one change every ten seconds is probably workable, as long as you don't have a ten second latency when asking for a change.

I think it would really depends on what game you're playing. From what I gathered from the article it's not really meant to replace a standard deck of cards but more aimed towards board games. People that are serious about board gaming will usually have 1 session/week , sometimes but rarely more, often less. So I'm sure on average each card will get more than 7 refreshes/week but it will probably be in the acceptable range.

Aaron Christophel is your guy for e-ink price tag hacking [1].

He's a friendly guy, he'll help you.

[1] https://www.youtube.com/@atc1441

The Waveshare ones are even powered purely by NFC. So they don't need a battery, yet you can rewrite them with ease.

I'm going to have to look into that

Oh wow, that’s so cool

Looks like you need a gateway (not that expensive but too expensive to just hack with those tags at home).

I’d love to find cheap e-ink tags that can just receive a picture over some cheap wireless protocol and display it.

The link was entirely random to show a similar mass produced product, I didn't do much research.

You can search for NFC ones on the same website, they're a few bucks more.

There are also Bluetooth variants which is more friendly to hacking at home (update over the air from farther away) but those look pricier.

Does anybody here know a Bluetooth (ideally) or NFC one? Preferably with a known protocol that has open source software... at least a known/open protocol to set the displays if not end-to-end open. I have wanted to play with one of these but haven't been able to find one that is easy to hack on.

I'd really like a $10-20 epaper display that I could update wirelessly on very low power, there are so many fun projects that could be done with that. There are a few dev boards that almost hit that price point but software support is really bad in my experience.

There's a pretty good set of videos here showing how to hack them: https://youtu.be/S44NSr37eoo

Thanks for this video!

It shows a nice layout with 3D-printed holder, pogo-pins, ESP32 Lolin as programmer, with CC2531 RF dongle as the access point.

Seen these at Ross and/or other discount stores. It boggled my mind. How could these possibly be cheaper than the staff swapping bits of paper. 10 year battery but I assume they break (and you have to walk around to find the broken ones) in 1-2 years, or get retail abuse, or other calamities.

The 4" ones (close to paper tag size) are $20.

I wonder if the cost savings is in eliminating the labor required to physically relabel things. I presume sending one person on patrol to look for the broken tags twice a week is far cheaper.

I can't see how. You need the staff in the store anyway (to check stock level, neaten up things, return merch to the proper location, etc), so they are already interacting at every location. Otherwise they spend a lot of time relatively idle. Are you really going to get that extra bit of time out of them productively?

It's mostly for dynamic pricing (based on time of day, number of customers, weather, you name it). It'd be more expensive and time consuming to send an employee with a label printer all over the store a couple of times a day.

The HFT model is coming to retail? I don't like this.

What happens if I put an item in my cart when the tag says it costs three shillings, but when I get to the register they want five?

Only time I've seen this was an IKEA in Shanghai about 5 years ago. They had a sign that said that umbrellas cost (equivalent to) $1 if it was raining outside and $3 if it wasn't. :)

You wouldn't need a digital, dynamic tag for that?

The only time I've seen dynamic pricing was the KMart blue light special.

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