Over the previous 20 years, e-paper has developed from an unique and costly show know-how to one thing low cost sufficient for use for grocery store value tags. Whereas such digital shelf labels at the moment are straightforward to search out, really re-using them is commonly tough because of a scarcity of documentation. Fortunately, [Aaron Christophel] has managed to reverse engineer many sorts of shelf labels, and he’s demonstrated the outcomes by turning one into an ultra-low-power clock known as Triink. It’s primarily based on a 128×296 pixel e-ink show paired with an nRF52832 BlueTooth Low-Vitality SoC and makes use of simply 65 micro-amperes on common: low sufficient to maintain it operating for greater than a 12 months on a single battery cost.

The clock is housed in an enclosure that’s easy however efficient: a 3D-printed triangular prism with a slot for the display screen and area for the 18650 lithium battery. One aspect may be opened to entry the interior parts, though that’s actually solely wanted to cost the battery. You may see how cleverly all the things snaps collectively within the video embedded beneath.

The CPU spends most of its time in sleep mode, solely waking up as soon as a minute to replace the show. With a purpose to save energy, [Aaron] wrote this routine in such a approach that it solely updates these pixels which have really modified. As soon as an hour, it fully refreshes the display screen with a purpose to stop burn-in. An built-in real-time clock retains monitor of time and may be adjusted via BlueTooth through the use of a smartphone app.

In the event you’ve obtained a bunch of comparable e-ink shelf labels gathering mud, you’ll find all of the design information and software program to construct your personal Triink on [Aaron]’s hackaday.io web page. In actual fact, you would possibly wish to browse round a few of his different tasks too: he’s managed to reverse engineer three-color e-ink value tags for example, and even mixed 300 shelf labels into an enormous e-ink show.