Our brain isn’t very good at binary calculation. It takes time to get used to it. We are stuck with decimal system and so most human friendly devices are based on it. But there can be as many number systems as you want. The popular ones are binary, octal, hex, and decimal and you may go up if you wish. Machines are great at binary number system. So before they calculate something all information needs to be converted in to binary. Then results are converted back to decimal so we could understand without trouble. If we skip last part we get results in binary. Some people simply don’t understand this but some do. If you feel comfortable with it then you can stick with it and look pretty weird.
Emanuele decided to make a project where digital numbers are involved. A binary watch seemed to be a great choice because you can learn binary numbers as you go and have unique thing on your wrist. The project isn’t a mind blower – four dedicated LEDs for hours and six for minutes. No special wiring is used – each LED has its own MCU pin what makes it simple to build and program. It is coin battery operated so power consumption is important. So clock is put in to sleep mode most of the time and waked up on timer overflow interrupt.