RGB LED Matrix

Do you want to create animations, games, or other fun activities that displays electronic color or want to place a colorful electronic “happy new year” on your wall? Phillip Burgess project on RGB LED matrix panels can bring this fantasy into reality. LED matrix panels are especially seen on walls or on buildings displaying electronic banners, animations or short video clips. 

 

To start this fancy project, he bought some packets from factory, one was 512 bright RGB LEDs arranged in a 16×32 grid on the front and the other had 1024 LEDs in a 32×32 grid. For one set for input and one for output that was backed with a PCB and IDC connectors. Apart from this, he had 12 16-bit latches which was used to drive the display with a 1:8 (16×32) or 1:16 (32×32) scan

 

 

Further, there is a requirement of 12 or 13 digital pins for panels comprising of 6 bit data, 6 or 7 bit control. This is accompanied by 5V power supply, at least a couple amps per panel. You will also need 2A or larger regulated 5V adapters and either a terminal block DC jack, or solder a jack from our DC extension cord. 

 

For your information, the designing of these displays are generally driven by FPGAs or other high speed processors and also they do not have built in PWM control of any kind. Therefore, you have to redraw the screen over ‘manually’ PWM to design the whole thing. After squeezing 12-bit color that is 4096 colors on a 16 MHz Arduino Uno, this display would really shine if driven by an FPGA, CPLD, Propeller, XMOS or other high speed multi-processor controller.

 

Further on an Arduino Uno or Mega, 12 digital pins are required and about 800 bytes of RAM to hold the 12-bit color image that stands double for the 32×32 matrix. 

 

 

There are 512 RGB LEDs in a 16×32 matrix but it is not possible to drive all 512 at once. As it will require a lot of current and would be really expensive to accumulate all pins together. Therefore, the matrix is divided into 8 sections that are interleaved to look better when refreshed, otherwise the stripes will be seen more clearly. On the PCB is 12 LED along with 16 outputs and they are constant current and can be controlled at once. In the design section, 192 outputs can control one line at a time, with each of 192 R, G and B LEDs either on or off. An FPGA or microcontroller determines the selection of section to currently draw.

 

The only drawback with this technique is absence of PWM control built in, despite being very fast and simple. If you want full color, you need to draw the entire matrix over and over again at very high speeds to PWM the matrix manually as the controller can only set the LEDs on or off. Therefore, you have to be a very fast controller if you want to do a lot of colors and motion video.

 

For elaborated and explained details, you can visit the blog of Phillip Burgess and try out some exciting video electronic walls.