Digital watches are a pretty neat idea, and are a great way to experiment with designing and building low-power circuits. That’s what [Eric Min] did with this neat smart watch build. It’s based around an nRF52832 SoC that does all of the heavy lifting, including connecting to a smartphone to get the time when the battery is replaced. It also has a decent quantity of blinky LEDs, which is important on any project of this type.
[Eric] freely admits that there are still some issues to overcome in his prototype. For one, the display tends to dim in use, probably because the 3V Lithium coin cell actually ends up delivering a bit less than that as it discharges, and the display is designed to work on a minimum of 3V. For the next version, he is thinking about using a 3.7V Lithium Polymer cell and a 3.3V regulator, which should be able to drive the display a little easier and keep it nice and bright. Or perhaps switch over to a nice OLED or eInk display.
Perhaps our favorite feature of the design from this 17-year old is the call-out on the back of the PCB: “I love you Mom and Dad”. Aww. I’ll bet your Apple Watch doesn’t have that, does it?