Sporting a new wristwatch to school for the first time is a great moment in a kid’s life. When it’s a custom digital-analog watch made by your dad, it’s another thing altogether.
As [Chris O’Riley] relates, the watch he built for his son [Vlad] started out as a simple timer for daily toothbrushing, a chore to which any busy lad pays short shrift unless given the proper incentive. That morphed into an idea for a general purpose analog timepiece with LEDs taking the place of hands. [Chris] decided that five-minute resolution was enough for a nine-year-old, which greatly reduced the number of LEDs needed. An ATtiny841 tells a 28-channel I2C driver which LEDs to light up, and an RTC chip keeps [Vlad] on schedule. The beautiful PCB lives inside a CNC machined aluminum case; we actually commented to [Chris] that the acrylic prototype looked great by itself, but [Vlad] wanted metal. The watch has no external buttons; rather, the slightly flexible polycarbonate crystal bears against a PCB-mounted pushbutton to control functions.