An Always-On ATtiny85 PCB Wristwatch

from hackster.io

Modern technology (e.g. cell phones) have alleviated some of the need for a wristwatch in order to tell what time it is. However, modern making technology (e.g. minuscule microcontrollers, 3D printing, and accessible PCB manufacturing. etc.) means that a wristwatch can not just be a timepiece and/or wealth indicator, but an ever-present testament to your making and electronics skill.

As seen here, Redditor Icosahedralizational created an LED watch, which uses 12 white LEDs arranged about the face to indicate hours and 12 blue LEDs that show minutes to the highest five-minute mark passed. Four more blue LEDs in the center of the face count up minutes after the 5-minute indication, and an ATtiny85 microcontroller with an RTC unit is implemented for watch control.

While other PCB watches are meant to be blank most of the time until a button is pressed, this device is designed as always-on. The tradeoff, of course, is that battery life between charges is estimated at hours, not months, though if reading such a device is slowed at all, one might just reach for a phone instead. The watch is still a prototype, so perhaps power consumption can be optimized to allow for extended usage.

Additional watch images can be found here, and you can even see it blinking away with additional wiring in the video below. Notably, the device’s “5700 Joules” label indicates both its energy capacity and is a reference to how vintage mechanical watches would label their number of jewels as an indicator of quality.