Discreet Mayor's Compact Tri-Color ePaper Display Is Built for a Long Battery Life

Pseudonymous maker "Discreet Mayor" has turned an affordable tri-color ePaper display into a standalone, long-life sunlight-readable information display — and has released the driver board used to make it tick along.

"This is a simple ePaper display that shows weather data, but can also display arbitrary information sent over a long-range wireless network," Mayor explains of their creation. "The trickiest part of all? Figuring out what you want to display on it."

The display chosen for the project is a Waveshare 5.9" ePaper unit that offers three colors: black, red, and the white background. Based on electrophoretic technology, the ePaper display needs power only when it changes states — making it ideal for battery-powered projects, with sunlight readability an added bonus.

"This turns out to have been a fairly simple project to put together," says Mayor. "It required designing a driver board for the Waveshare 2-color 5.9" ePaper display, writing a bit of firmware and creating a 3D-printed enclosure."

That driver board is designed for use with a Texas Instruments CC1312, a system-on-chip which offers sub-gigahertz radio connectivity along with a single 32-bit Arm Cortex-M4F microcontroller core, 80kB of RAM, and 352kB of flash storage — along with an analog input used, via a "resistor divider bodge," to keep an eye on the battery charge level.

"The battery will last months on a single charge, but if I redid this project, I'd opt for a black and white [display]," Mayor notes. "The red and black version takes multiple seconds to update, consuming milliamps of current while doing so. The black and white version updates in less than a second, which would lead to many years on even a small LiPo battery."

More details are available on Mayor's Hackaday.io page, while the design file for the driver board has been published to EasyEDA under an unspecified open hardware license.