My +Raspberry Pi
controls three 7 segment modules with only 11 gpios in use. (Normally one would need 24 gpios)
The little java program I wrote for this is cheating a bit ;). It turns on the third segment, sets the number and turns it off. Then it turns on the second segment, sets the number and turns it off. Same for the first segment.
Because this happens so incredibly fast (I have a 1ms sleep between switching segments) you get an optical illusion whereas it seems as if all three segments were online at the same time.
Evidently my oneplusone camera is too good for this cheat and catches a lot of flickering. I could probably get rid of most of the flickering by adding a capacitor (with a diode to prevent back flow into the pi). But hey, proof of concept is everything ;p
This way one could use n number of segments and only use n+8 number of gpios.
Sadly the first element is damaged, the upper right led is dead. :(#gpio #raspberrypi