16x32 LED Matrix not powering/displaying correctly

Using Arduino Displays
1

Hi all, I'm a arduino newbie and I recently got this 16x32 LED Matrix to start playing around with displays w/ the arduino.

I've run into some problems, and I was hoping one of you could lend some of your insight!

The goal is to get the display to run a test example that draws various shapes and then ultimately displays this

1200×900 239 KB
on my Arduino Uno, using this code and the supplied libraries:

// testshapes demo for Adafruit RGBmatrixPanel library.
// Demonstrates the drawing abilities of the RGBmatrixPanel library.
// For 16x32 RGB LED matrix:
// http://www.adafruit.com/products/420

// Written by Limor Fried/Ladyada & Phil Burgess/PaintYourDragon
// for Adafruit Industries.
// BSD license, all text above must be included in any redistribution.

#include <Adafruit_GFX.h>   // Core graphics library
#include <RGBmatrixPanel.h> // Hardware-specific library

#define CLK 8  // MUST be on PORTB! (Use pin 11 on Mega)
#define LAT A3
#define OE  9
#define A   A0
#define B   A1
#define C   A2
RGBmatrixPanel matrix(A, B, C, CLK, LAT, OE, false);

void setup() {

  matrix.begin();
  
  // draw a pixel in solid white
  matrix.drawPixel(0, 0, matrix.Color333(7, 7, 7)); 
  delay(500);

  // fix the screen with green
  matrix.fillRect(0, 0, 32, 16, matrix.Color333(0, 7, 0));
  delay(500);

  // draw a box in yellow
  matrix.drawRect(0, 0, 32, 16, matrix.Color333(7, 7, 0));
  delay(500);
  
  // draw an 'X' in red
  matrix.drawLine(0, 0, 31, 15, matrix.Color333(7, 0, 0));
  matrix.drawLine(31, 0, 0, 15, matrix.Color333(7, 0, 0));
  delay(500);
  
  // draw a blue circle
  matrix.drawCircle(7, 7, 7, matrix.Color333(0, 0, 7));
  delay(500);
  
  // fill a violet circle
  matrix.fillCircle(23, 7, 7, matrix.Color333(7, 0, 7));
  delay(500);
  
  // fill the screen with 'black'
  matrix.fillScreen(matrix.Color333(0, 0, 0));
  
  // draw some text!
  matrix.setCursor(1, 0);   // start at top left, with one pixel of spacing
  matrix.setTextSize(1);    // size 1 == 8 pixels high
  
  // print each letter with a rainbow color
  matrix.setTextColor(matrix.Color333(7,0,0));
  matrix.print('1');
  matrix.setTextColor(matrix.Color333(7,4,0)); 
  matrix.print('6');
  matrix.setTextColor(matrix.Color333(7,7,0));
  matrix.print('x');
  matrix.setTextColor(matrix.Color333(4,7,0)); 
  matrix.print('3');
  matrix.setTextColor(matrix.Color333(0,7,0));  
  matrix.print('2');
  
  matrix.setCursor(1, 9);   // next line
  matrix.setTextColor(matrix.Color333(0,7,7)); 
  matrix.print('*');
  matrix.setTextColor(matrix.Color333(0,4,7)); 
  matrix.print('R');
  matrix.setTextColor(matrix.Color333(0,0,7));
  matrix.print('G');
  matrix.setTextColor(matrix.Color333(4,0,7)); 
  matrix.print("B");
  matrix.setTextColor(matrix.Color333(7,0,4)); 
  matrix.print("*");

  // whew!
}

void loop() {
  // do nothing
}

Here's a preview of my results.

I am using this set up guide from Adafruit, designed specifically for this display. They don't include a schematic, but they have a page showing all the connections, which I've quadruple checked and ensured I've followed correctly.

I believe the problem is either with the outside power supply, the grounds on the board or possibly the scan rate of the display.

I'm going to break up what the instructions say, vs what I've done on each relevant section:

  • Power
  • Connections
  • Code/Library

Part 1: Power
My display requires at least an outside 5v, 2a power supply via a Molex-style header:

Per Adafruit's instructions, I found a 5v/2a DC power source, and wired it directly to the molex:

The guide doesn't specify how to power the Arduino, but I have it being powered through the USB cable to my computer.

Problem: I have not been able to get the display to power through the 5v/2a power supply. When I attach the display to just the arduino and power it through that, I get the results in the video above. However, when I try to attach the display to the 5v/2a power supply via the molex, the display completely stops working.

I'm completely new to circuitry/arduino, so I'm not sure if it's my wiring set up or what.

Part 2: Connections

Using this part of the guide.

I'm pretty sure this part is done correctly, at least per the instructions. My set up is the same as this:
Upper RGB Data
Lower RGB Data
Row Select Lines
LAT Wire
CLK
OE

And my actual board:

And to the display:

Problem: This display requires 4 grounds, but the arduino only has 3 ground spots. I've put two of the grounds in 2 of the GND spots on the board, but the remaining 2 I have connected via the breadboard. I originally tried to ground all 4 via the breadboard, but the display's LEDs started fading. So, I'm wondering if the lack of a 4th ground spot on the Arduino is causing my trouble.

Part 3: Code/Libraries

I don't think I have any issues here, I've properly installed the libraries and I completely understand the code (which is at the top of post).

Here is the code section of the guide if you want to review it.

Anyways, I know this is a big info dump, but I would appreciate any ideas you guys might have!

Thanks!

2

same problem with me :o