The 8x8 LED matrix is a building block. There is no processor or circuitry other then then LEDs and the copper traces. It is simply an eight by eight 64-LED matrix on a PCB. The 8x8 has 16 pins on one edge, 8 connect to the rows and the other 8 to the columns. This allows the maker to use their preference of controlling circuitry.
1. After the board is etched and drilled, solder on the jumpers. (Important, for this project the LEDs are on the solder side of the PCB)
2. Next, place the board on a piece of flat (high density) Styrofoam, with the cooper side up.
3. Using a thin material as a spacer, like the thin 1/8” brass strip that is in the photo, place one row of LEDs over the spacer and though the holes.
4. Since the Styrofoam is ridged the LEDs should be able to hold themselves up strait after you remove the spacer. (You must remove the spacer before you solder.)
5. Check the alignment once the spacer is removed, then solder.
6. Only solder one row at a time or you will be more likely to melt a neighbouring LED.
The PCB eps file is available below. See the PCB Notes for some tips on how to use the eps files.
For my initial project with the 8x8 I used the MAX7219 which is controlled by a PIC16F688 using a “SPI” type connection. The MAX7219 does the multiplexing and the current limiting for the LEDs.
1. Serial buffer mode. The PIC receives serially 2-byes of data from my computer at a time. The first byte is the row and the second is a value from 0 to 255 which represents which LEDs will be on.
2. Game mode. A four sided pong game where you try to keep the “ball” from leaving the square. You control the paddle with an optical encoder. (For now the ball only goes from one side to the other.)
The 8x8 is designed to fit into an Ikea RIBBA 9x9” picture frame. I’m going to use mine with a piece of translucent white plastic in place of the glass, to act as a diffuser.
I thought it would be good to have some way to control the spread for the light so that the light from neighbouring LEDs would not mix. To do this I cut out a series of circles in card board using our laser cutter.
They where stacked up and glued together. The photo on the right shows the LEDs in their pockets.
The actual 8x8 PCB just has a set of pin headers. These pin poke out the back of the frame. This way I can change the controller without taking the display apart.
Initially I used the MAX7219 LED controller again, you can see it here on the proto-board.
Here is what the frame looks like when assembled. And on the right when lit. I was pretty happy with the milky white diffuser, since it gave the frame an unassuming look and hide the LEDs well, until they where lit.
Copyright SpikenzieLabs 2019