Figures

Today I tried to create the first figure on the LED cube, an O. In order to do this I had to switch between two patterns, two dots at the bottom in the middle and at the top in the middle, and two dots to the left in the middle and at the right in the middle. The trick was ensuring that the screen is blank in between, because any transistion LED will seem lit as well. The code became:

Display
  call Blank
  movlw 96
  movwf PORTC
  movlw 6+96
  movwf PORTB
  call Blank
  movlw 144
  movwf PORTC
  movlw 9+144
  movwf PORTB
  goto Display
Blank
  movlw 240
  movwf PORTC
  clrf PORTB
  retlw 0

Next step would be to have the delay loop automatically switch between two patterns... Although I might need more than two for complex figures. At 20 MHz it is completely invisible that such switching is taking place, except for the LED being slightly dimmer. Biggest problem is still that the bottom LED make it seem like the LED at the top are slightly lit. I might need to reduce their transparancy somehow.