Recreating an old-school mechanical split-flap display with Arduino
Those old-school split-flap character displays are super fun to look at, not to mention listen as well from the click each time a letter changes. Sadly, these have largely been replaced by more modern and efficient LED screens, leaving those who love the tactile feel a little on their own. Thankfully, Dave Madison has created a DIY version that supports 40 total characters per digit with eight digits total.
The whole thing is housed inside a laser-cut acrylic enclosure, with each digit module consisting of a single stepper motor, a wheel with cutouts for 40 pins, and the roll of split cards. Madison was able to generate 39 different characters ranging from the 26 letters, 10 digits, and three extra punctuation marks onto a piece of vinyl which he then cut out and glued onto the cards.
In terms of electronics, the system uses a custom-designed PCB that packs four status LEDs, a shift register, stepper motor drivers, and headers for inputs and outputs. An Arduino Nano runs the firmware that takes in characters from the serial terminal and converts them into split card movements using some clever math.
In the future Madison plans to add the capability for WiFi control along with a web server. But even now the project looks great, and you can read more about it here in its write-up.