You thought that binary clocks are hard to read? Try to tell time by looking at QR clock. Ch00f decided that QR codes are no so useful as they are pushed everywhere. First thing is that it is practically non readable by human. At least now until everyone gets smart lenses or glasses to translate them on the fly. Of course you can use smart phone to read those, but this require additional actions like opening app taking picture and converting only to see whats written. QR code needs at least 21×21 pixel square, so there are nine 8×8 LED matrices used.
Clock is driven by Atmega328 microcontroller which runs clock in firmware. Another issues ch00f faced were QR codes. There were two ways of having QR code for each minute of the day (total 1440). store each of them would take more memory than AVR can provide. So second option left – generate them dynamically. Also he added a photo transistor to monitor ambient light and dim LEDs so it distracted less. Clock displays time only but QR code could also space a date function.