Help with Multiplex Code

Projects Programming
1

I created an 8x8 matrix. All the LEDS turn on so the hardware must be okay. I tried running an example sketch:

//Pin connected to latch pin (ST_CP) of 74HC595
const int latchPin = 6;
//Pin connected to clock pin (SH_CP) of 74HC595
const int clockPin = 12;
////Pin connected to Data in (DS) of 74HC595
const int dataPin = 7;

int rowArr[8] = {5,4,3,2,8,9,10,11}; // Pins where each Cathode is connected

byte data;
byte dataArray[8];

void setup() {
  //set pins to output because they are addressed in the main loop
  pinMode(latchPin, OUTPUT);
  Serial.begin(9600);
  pinMode(5,OUTPUT);
  pinMode(4,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(2,OUTPUT);
  pinMode(8,OUTPUT);
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(11,OUTPUT);

  //Binary notation as comment
  dataArray[0] = 0xFF; //0b11111111
  dataArray[1] = 0x81; //0b10000001
  dataArray[2] = 0x81; //0b10000001
  dataArray[3] = 0x81; //0b10000001
  dataArray[4] = 0x81; //0b10000001
  dataArray[5] = 0x81; //0b10000001
  dataArray[6] = 0x81; //0b10000001
  dataArray[7] = 0xFF; //0b11111111


  digitalWrite(5,HIGH);
  digitalWrite(4,HIGH);
  digitalWrite(3,HIGH);
  digitalWrite(2,HIGH);
  digitalWrite(8,HIGH);
  digitalWrite(9,HIGH);
  digitalWrite(10,HIGH);
  digitalWrite(11,HIGH);
 
}

void loop() {

  for (int j = 0; j < 8; j++) {
    //load the light sequence you want from array
    data = dataArray[j];
    //ground latchPin and hold low for as long as you are transmitting
    digitalWrite(latchPin, 0);
    //move 'em out
    shiftOut(dataPin, clockPin, data);
    //return the latch pin high to signal chip that it 
    //no longer needs to listen for information
    digitalWrite(latchPin, 1);
    digitalWrite(rowArr[j],LOW);
    delay(100);
    digitalWrite(rowArr[j],HIGH);
  }
}



// the heart of the program
void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
  // This shifts 8 bits out MSB first, 
  //on the rising edge of the clock,
  //clock idles low

  //internal function setup
  int i=0;
  int pinState;
  pinMode(myClockPin, OUTPUT);
  pinMode(myDataPin, OUTPUT);

  //clear everything out just in case to
  //prepare shift register for bit shifting
  digitalWrite(myDataPin, 0);
  digitalWrite(myClockPin, 0);

  //for each bit in the byte myDataOut�
  //NOTICE THAT WE ARE COUNTING DOWN in our for loop
  //This means that %00000001 or "1" will go through such
  //that it will be pin Q0 that lights. 
  for (i=7; i>=0; i--)  {
    digitalWrite(myClockPin, 0);

    //if the value passed to myDataOut and a bitmask result 
    // true then... so if we are at i=6 and our value is
    // %11010100 it would the code compares it to %01000000 
    // and proceeds to set pinState to 1.
    if ( myDataOut & (1<<i) ) {
      pinState= 1;
    }
    else {  
      pinState= 0;
    }

    //Sets the pin to HIGH or LOW depending on pinState
    digitalWrite(myDataPin, pinState);
    //register shifts bits on upstroke of clock pin  
    digitalWrite(myClockPin, 1);
    //zero the data pin after shift to prevent bleed through
    digitalWrite(myDataPin, 0);
  }

  //stop shifting
  digitalWrite(myClockPin, 0);
}

Instead of it lighting up the LEDS according to the Data array, it just turns them all on. Any ideas?

2

I guess there must be a wiring error.
The comments in the code:

int rowArr[8] = {5,4,3,2,8,9,10,11}; // Pins where each Cathode is connected

imply the cathodes of the LEDs are connected to the above pins.
When these pins are HIGH, the LEDs in the corresponding row are off.
This code in your setup() switches them all off:

  digitalWrite(5,HIGH);
  digitalWrite(4,HIGH);
  digitalWrite(3,HIGH);
  digitalWrite(2,HIGH);
  digitalWrite(8,HIGH);
  digitalWrite(9,HIGH);
  digitalWrite(10,HIGH);
  digitalWrite(11,HIGH);

Just to confirm it, put a delay of say 10 Seconds after this code. If the LEDs light during setup, there must be a wiring error.

Post a schematic (a hand drawn one would be OK) for more comments.