Build This Stylish PCB Binary Watch for Your Wrist with a Handful of Parts

Embedded engineers tend to think in binary. Some even go so far as to have clocks or watches that display the current time in this base-two number system. So, inspired by other binary watches, an engineer, hacker, and Assistant Professor, known in electronics communities as taifur, designed a stylish PCB binary watch that any base-two time-telling enthusiast would be proud to wear.

This PCB binary watch is a single PCB driven by an ATmega328P. This 8-bit processor is best known for the core of an Arduino Uno or Nano. A real-time clock (RTC) chip keeps track of the actual time. Taifur chose the Analog Devices/Maxim-IC/Dallas Semiconductor DS3231 IC. This RTC is ultra-stable even with extreme shifts in temperature. There are 13 1206 SMD LEDs on the face and a CR2032 coin cell on the back.

The time display is binary-coded-decimal (BCD.) Up to four LEDs represent individual digits of a time display. So, if you can read 0-9 in binary, you can tell the time with this watch! Read each column of LEDs as a single digit. The example taifur provided above is 1:39.

While this board is entirely surface mount components, their size should be large enough for anyone to solder. Ideally, you should order a stencil to go with the PCB. Regardless, the relatively large IC packages and 1206 LEDs should do a decent job snapping into place with surface tension while soldering with hot air.

Speaking of the PCB, make sure you order it with a Gold Finish (ENIG). Not only are the traces far more stylish looking, but they are also more resistant to corrosion. Low-cost PCBs are typically finished with HASL, which can corrode enough to be visible but not enough to affect circuit performance.

To learn more about the circuit design and the software, check out this guide on how to build this PCB binary watch. Taifur documented every step of the build process with extreme detail!