“Repurposing boring eInk electronic shelf labels / price tags into useful photo frames / status displays, with blackjack and hookers custom firmware and greyscale! Quick video (partially sped up) here: [LINK]. There you can see association, image download with progress bar, and image display in greyscale + yellow.
What they are and what they are for
They have been appearing in stores since the early 2000s, but have really become prevalent in the last five to seven years! Also known as ESL (Electronic Shelf Labels), they basically allow the store to change prices dynamically as they see fit, without having to send a person out with a new printed piece of paper to place unto the shelf. The extra benefits include ability to show off more of the product’s features (bullet point lists often shown on large price tags), change that shown feature list (advertise differently based on current day/month/etc), and use colors (last five years brought red and yellows to the previously only-black-and-white electronic shelf labels). There is a lot more marketing fluff about why ESLs are cool, and you can read all about it on your own time!
Common features
Most of the current-generation ESLs are updated wirelessly, using some sort of a custom protocol. The company “Pricer” distinguishes themselves here, using InfraRed instead, making their devices completely useless for us. InfraRed is dead, guys, get over it! Anyways, all of the protocols are of cource not documented, so we’re on our own.
Most of the current-generation ESLs use eInk displays (aka: EPD - electrophoretic displays). Why? The main selling point is power. eInk uses none while it is showing a static image. You’ve likely seen a screen of this type last you looked at an eBook reader, like a Kindle. They do need power to change their contents (quite a lot actually), and are a giant pain in the rear to work with in general, but more on that later. Having a screen that needs no power to show prices, combined with the fact that prices do not change often, leads to good battery lives. Multiple years is the advertised figure. Based on my work below, I believe it entirely, and I was even able to improve on it!”