When you need to time something, you can use a rotary kitchen timer that is easy to set and does a good job of counting down the minutes, or an electronic timer that can drill down to a more granular level, but requires you to push quite a few buttons to set it up. This more complicated button interface causes some, like hacker “bobsonh,” to simply not use a timer on tasks like brewing tea that need sub-minute accuracy, leading to over-brewed beverages.
Bobsonh, however, no longer has that problem as he’s come up with a digital timer, which can be set with the press of a single button and the turn of a dial. It’s powered by an ATtiny85 processor, which takes input from the button on top, as well as a ring on the side that is sensed with two optical switches. Since it has a limited number of IO, the chip was set up to use the reset pin as an input based on instructions found here to accommodate the system’s needs.
Physically, the design is quite pleasing, and is constructed with 3D-printed parts including a white base and yellowish ring. Be sure to check it out on display in the video below!