
Open-source hardware and software toolkit for reverse-engineering and communicating with infrared-based electronic shelf labels. Includes custom transmitters, protocol analysis, and display manipulation tools.
Collection of software and hardware tools, their source code and design files for communicating with infrared based Electronic Shelf Labels.
See http://furrtek.free.fr/index.php?a=esl for reverse-engineering of the system, the protocol and electronics.
Thanks to @david4599 for infos about color tags.
What can this be used for ?
To have fun experimenting with mass produced devices ! Compatible ESLs can be found on eBay, or directly from stores shelves ;)
The e-paper ones can make cool badges:

Which brands of ESLs are compatible ?
You'll have to guess from the picture above and the page on my website. Hint: it's an anagram of this repo's name.
Can my phone/tablet/handheld/IrDA-capable device work as a transmitter ?
No. The proprietary protocol uses a carrier in the MHz range and the symbol timing must be very precise. IrDA controller limitations and OS latency makes it impossible.
It's possible with an overclocked Gameboy Color, but who wants to do that ?
Can this be ported to the Flipper Zero ?
Yes. However I have very little interest in doing free work for beggars who get excited by remotely opening Tesla charge ports.
All the info you need is here. DIY :)
Can I change the display of all ESLs in a store at once ?
No. For two reasons:
Is possession and use of such devices legal ?
There's no cracking, exploit, patent or copyright infrigement going on so IMO it's safe to assume this is perfectly legal. Just don't try changing price displays so you can get discounts, the price in the store's database obviously remains unchanged so you'll end up having to pay the correct price anyways.
My tricolor-capable ESL shows red garbage after an image update Transmit the image in tricolor mode. Transmitting black and white images to tricolor ESLs doesn't clear the red layer.