As you may have heard of my previous projects, I attempted in making an LED matrix game, it worked, but it wasn't that great. This version is a step further from the previous. It has a larger display, 8x8 dual color matrix display, and it has refreshing circuitry to help the PIC micro with displaying the data.
Here are some pics:

cool!!!! make few more of those and put them together and program it like the game "stackers" which is rigged until the machine gets the X amount of wins. nice job

What do you mean by "refreshing circuitry", what did you use? Great job nicely done. Did you cut all the wires yourself? Lots of wires.

Yes, I cut all the wires myself, very time consuming. Anyway, the "refreshing circuits" are two 4514 1 to 16 binary decoders. I used these to save pins, instead of connecting 16 outputs, for the red and green, I connected the red and green to the 4514's, saving me 8 pins. For the ground signals, an inverted 4028 1 to 10 decoder (I didn't have a 7442, which is what I should use next time). The 4028 saves 4 pins. After I have finished making a final prototype of this, I might make a 16x16 dual color version, or maybe even RGB.

EDIT EDIT I accidentally said 4511, its 4514

I never used one of those before. Those could help a lot with a very large cube (6x6x6 anyone?).

When you said "refreshing circuits" I though you had some automatic refresh circuit.

How do those decoders outputs work? Do you get enough current to keep the colors the same when you have red and green on? I had a problem with the 3x3x3 cube where if all the colors were on red would only be shown due to the fact that the red channel needs a lower voltage to start conducting making all the power go through it. That only happens if you source more current then you sink.

When I use the refreshing circuits, the colors stay relatively the same brightness when red and green are on, it also depends on the speed at which the device is multiplexing, that also effects brightness.
The 4514 works like this (small example):

inputs:
0___|\/|___1 -outputs:
0___||||___0
0___||||___0
0___||||___0

Right now all of the inputs currently have a low signal, and as you can see for the outputs, output no. 0 is high, the inputs on the 4514 use the binary system to convert to shifted outputs on the right.


inputs:
1___|\/|___0 -outputs:
0___||||___1
0___||||___0
0___||||___0

Now the first input has a high signal (binary 1) the output is sending a high to output no. 1


binary 2
inputs:
0___|\/|___0 -outputs:
1___||||___0
0___||||___1
0___||||___0

binary3
inputs:
1___|\/|___0 -outputs:
1___||||___0
0___||||___0
0___||||___1

And for the two above, we have binary 2 and 3. You can see by the outputs how it works.
The 4514 has a 'strobe' pin, this pin, I believe when set to high, keeps the output at its current pin no. until the 'strobe' pin is set to low again.

I read the datasheets before.

To keep the brightness at a decent level you need to boost the voltage or current, if you voltage is at lease 5V already. You have to be careful when doing this because if you set it up right then if your system decided to freeze you could burn out the LED that were on. LED can handle a lot higher bursts of currents then constant current. You can get them to almost appear as if they were not multiplexed. You would need to have the code use an interrupt so you have a constant refresh rate like the new 3x3x3 or the 4x4x4 cubes.

The problem I had was only if the red LED and blue or green were on at the same time. Red would take over and mask the other colors.

I do believe that the red LED , whether it's alone, or inside with another LED, is the LED that requires the most Mili amperage and voltage. When I connect some LED's to my breadboard once, I noticed that red was able overcome mostly all of the LED's, it would be a good idea to multiplex each color, rather than have them all on at once.

Red LED have a lower "on" voltage then blue or green and I believe requires more mA like you said. They do not require more voltage but actually less. A red LED will light at a much lower voltage then blue or green.