LED cube video

And here is the video showing the result.

Source code for LED cube control

The source code for the LED cube control is now available. Basically PORTB and PORTC of the PIC16F57 (which is actually a low end device) are used to control the output. I'm looping one bit through PORTB and one bit through PORTC to address all LED.

Fourth layer picture

This is the LED cube with the fourth layer completed. It worked immediately: I wrote a small program to test individual control of the LED and was succesful at lighting each one individually. Now it is time for the hard part: creating animations.

Fourth layer

The fourth layer is finished, but not attached yet. Hopefully that will happen tomorrow, together with my first animation. Video should be provided.

Third layer

And here is the third layer of the cube. I also rewired the connections so the cathodes and the anodes are each on their own port. One more layer, which doesn't need any more connections, and the circuit is finished.

Pattern

I succeeded in creating a two part pattern loop. An issue was that blanking the image in between each shift caused the LED to be less bright. By adding a delay the impact of the blank could be reduced, however, initially there was too much delay and the pattern seemed to be blinking. The correct code is as follows:

PatternDelay
  call Blank
  movf p1,w
  movwf PORTC
  movf p1+1,w
  movwf PORTB
  call SmallDelay
  call Blank
  movf p2,w
  movwf PORTC
  movf p2+1,w
  movwf PORTB
  call SmallDelay
  decfsz delay+1,f
  goto PatternDelay
  decfsz howlong,f
  goto PatternDelay
  retlw 0

Here the two patterns are in p1 and p2. As you can see it is relatively easy to extend to more patterns. The next step would be to write an application that can find the minimum sets needed to display a certain pattern.

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.