Help Coding a Direct Drive LED Matrix

Other Hardware LEDs and Multiplexing
1

Hi all,
I running a Mega 2560, to run a 16x16 LED Matrix. Transistors control each row and column, and there are 100k resistors to limit current to the board. Here's a schematic. http://i.imgur.com/nhjtxMx.png I was hoping to Direct Drive the matrix as seen here.Arduino Playground - DirectDriveLEDMatrix After Playing around with it for a bit, I managed to make the letters scroll correctly, but only on the bottom 15 rows, and the brightness isn't good enough. The letters are also upside down. I believe the issue is with the int pins[55] portion. Removing or adding pins makes the matrix not work at all. Here's the code.

[Here's the Code]
#include <FrequencyTimer2.h>
#define SPACE { \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ,0}, \
}

#define H { \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
}

#define I { \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
  {1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0}, \
}
byte col = 0;
byte leds[16][16];

int pins[55]= {-1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35,36,37,38,39,40,41,42,43,44,45,46,47,
48,49,50,51,52,53,54};

int cols[16] = {pins[23], pins[25], pins[27], pins[29], pins[31], pins[33], pins[35], pins[37], 
                pins[39], pins[41], pins[43], pins[45], pins[47], pins[49], pins[51], pins[53]};

int rows[16] = {pins[22], pins[24], pins[26], pins[28], pins[30], pins[32], pins[34], pins[36], 
                pins[38], pins[40], pins[42], pins[44], pins[46], pins[48], pins[50], pins[52]};

const int numPatterns = 3;
byte patterns[numPatterns][16][16] = {H,I,SPACE};
 
int pattern = 0;

void setup()
{
  for (int i = 1; i<= 32; i++) {
    pinMode(pins[i], OUTPUT);
  }
  for (int i = 1; i <= 32; i++) {
    digitalWrite (cols[i - 1], LOW);
  }
  for (int i = 1; i <= 32; i++) {
    digitalWrite (rows[i - 1], LOW);
  }
  
  clearLeds();
  
  FrequencyTimer2::disable();
  FrequencyTimer2::setPeriod(2000);
  FrequencyTimer2::setOnOverflow(display);
  
  setPattern(pattern);
  
  
  // put your setup code here, to run once:
   
}

void loop()
{
  pattern = ++pattern % numPatterns;
  slidePattern(pattern, 60);
}
void clearLeds() {
  for (int i = 0; i < 16; i++){
    for (int j = 0; j < 16; j++){
      leds[i][j] = 0;
    }
  }
}
void setPattern(int pattern) {
  for (int i = 0; i < 16; i++) {
    for (int j = 0; j < 16; j++) {
      leds[i][j] = patterns[pattern][i][j];
    }
  }
}
void slidePattern(int Pattern, int del) {
  for (int l = 0; l < 16; l++) {
    for (int i = 0; i <15; i++) {
      for (int j = 0; j < 16; j++) {
        leds[j][i] = leds[j][i+1];
      }
    }
   for (int j = 0; j < 15; j++) {
     leds[j][15] = patterns[pattern][j][0 + l];
    }
    delay(del);
  }
}

void display() {
  digitalWrite(cols[col], LOW);
  col++;
  if (col == 16) {
    col = 0;
  }
  for (int row = 0; row < 16; row++) {
    if (leds[col][15 - row] == 1) {
      digitalWrite(rows[row], HIGH);
    }
    else {
       digitalWrite(rows[row], LOW);
    }
  }
  digitalWrite(cols[col], HIGH);
}

[/Here's the Code]

Any help is appreciated. Thanks

2

and there are 100k resistors to limit current to the board.

No there is nothing to limit the current through the LEDs.
Using common emitters circuit to drive the rows is silly, you will never get a voltage of greater than 4.3V. You need a PNP top level switch.

I was hoping to Direct Drive the matrix as seen here.Arduino Playground - HomePage

Bad tutorial that exceeds current limits on the arduino.

The letters are also upside down

Just the way you wired it up / defined the arrays.

3

Any explanation for the lack of brightness? It seems to predictably fade after the first 5 rows?

4

Disregard that last post. The issue was in the setup portion of the code, working fine now. Thanks for your help.