Simple image display for YFRobot 8x8 Dot Matrix display (controller with dual serial 74HC595 chips)

gistfile1.txt

/*
Simple image display for YFRobot 8x8 Dot Matrix display (controller with dual serial 74HC595 chips)
Author: Andy Qua
Date: 22nd Jan 2022
*/

int dataPin = 10;             // The Serial Data Pin to the Shift Register (SER on board)
int latchPin = 8;             // The Latch Pin to the Shift Register (RCK on board)
int clockPin = 7;             // The Clock Pin to the Shift Register (SRCK on board)

// Our images
byte images[][8] = {{
  // Smile
  B00000000,
  B11100111,
  B10100101,
  B11100111,
  B00000000,
  B10000001,
  B01111110,
  B00000000
},
{
  B00011000,
  B00100100,
  B01000010,
  B11111111,
  B10000001,
  B10011001,
  B10011001,
  B11111111,
}};

int columnPositions[8] = { 1, 2, 4, 8, 16, 32, 64, 128 };
int counter = 0;
int imageNr = 0;

void setup()
{
  pinMode(dataPin, OUTPUT);    // Configure Digital Pins
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
}


void loop() {
    // Every 1000 iterations round the loop switch images
    if ( counter == 1000 ) {
      counter = 0;
      imageNr = imageNr == 1 ? 0 : 1;
    }
    counter += 1;

    // Pointer to the image we want to draw
    byte *image = images[imageNr];

    // Draw image
    for ( int row = 0 ; row < 8 ; ++row )
    {
        int rowVal = image[row];

        // We invert the rowVal as 0 is on and 1 is off!
        writeOutput(~rowVal, columnPositions[row]);
    }

}

void writeOutput( int rowVal, int col  )
{
  digitalWrite(latchPin, LOW);                    // Pull latch LOW to send data
  shiftOut(dataPin, clockPin, MSBFIRST, rowVal);  // Send the row data byte
  shiftOut(dataPin, clockPin, MSBFIRST, col);     // Send the column data byte
  digitalWrite(latchPin, HIGH);                   // Pull latch HIGH to finish sending data
}