This Clock Makes It Look as If the Time Diffuses Between Two LED Matrices
David Johnson-Davies' minimal Diffusion Clock shows the hour and minutes on two 8x8 I2C LED displays.
For his latest Technoblogy project, David Johnson-Davies has designed a Diffusion Clock that tells the time on a pair of I2C 8x8 matrix displays, “diffusing” between time values. According to the project's write-up, “Every minute the display disappears randomly, a dot at a time, to a blank display, and then the new time appears a dot at a time, making it look as if the time diffuses between the two displays.”
Each of the two matrices shows a pair of numbers in an HH:MM format. These digits are squeezed in a 3x7 pixel format, with the exception of the possible “1” at the beginning at 2x7, saving room for a colon for separation. Control of this minimal display is done via an ATtiny85 microcontroller, along with an 8MHz crystal. Components are nicely arranged on a breadboard, with a single button used to set the time. Power is provided by a rechargeable 3.7V LiPo battery.
Different sections of the code are explained on in Johnson-Davies' article, and the entire routine is also available for your perusal or usage here. Given the setup, maintaining the time would be dependent on keeping things energized, and perhaps it’d be feasible to add a RTC unit in a different iteration. On the other hand, its current low parts count and clean breadboard layout are quite satisfying.