Chen Liang's Smart Arduino Watch Faces Are Built with LVGL and SquareLine Studio

Electronics engineer Chen Liang has penned a guide to turning an Arduino-connected circular display into a convincing analog watch — using the Lightweight and Versatile Graphics Library (LVGL) and SquareLine Studio.

"Watch faces have many possibilities," Liang explains, "[but] this [guide] only focuses on analog watch faces. But it will not limited your creativity, you can use [a] similar method [to] design non-analog watch face. Any Arduino-supported dev device with color display should be OK."

Although Liang's guide, as above, doesn't necessarily need a circular display, using one definitely provides a more convincing finished product — and for those worried about the complexities of working with a round canvas, such displays are exposed to the host device as a square display whose corners are simply cut off and rounded.

"The graphic design material source is better in vector format," Liang explains, referring to the ability for vector graphics to be scaled to any size without loss. "[But] vector graphics are too complicated for a MCU [Microcontroller Unit]. So MCU program mainly using bitmap image as image source."

To get around this, Liang advises finding watch-face imagery, including hands, in vector format then converting them into bitmap PNGs. For some source imagery, including an escapement mechanism visible through the face of a real mechanical watch, capturing frames from a video is required — then everything is fed into SquareLine Studio to create the actual watch design, the output of which is then given life through an Arduino program to set the time and make the UI functional.

Liang's full guide is available on Instructables now, with a video of the project available on Bilibili.