dtokez:
I was wondering about a similar effect I had seen at a shopping centre over christmas. I think there were more LED's than 20 though and the motion looked extremely fluid. I will upload the video I took when I get home
This is possible if you use more pins:
Formula is Number of charlieplexed LED's = N * (N-1)
2 IO Ports allows 2 LEDs, LEDs = 2 * ( 2 - 1 )
3 IO Ports allows 6 LEDs, LEDs = 3 * ( 3 - 1 )
5 IO Ports allows 20 LEDs, LEDs = 5 * ( 5 - 1 )
6 IO Ports allows 30 LEDs, LEDs = 6 * ( 6 - 1 )
7 IO Ports allows 42 LEDs, LEDs = 7 * ( 7 - 1 )
8 IO Ports allows 56 LEDs, LEDs = 8 * ( 8 - 1 )
9 IO Ports allows 72 LEDs, LEDs = 9 * ( 9 - 1 )
10 IO Ports allows 90 LEDs, LEDs = 10 * ( 10 - 1 )
And so on...
Only restriction is you number of IO pins on your IC