Sparkfun RBG LED Matrix backpack by Vanessa Carpenter, Mads Høbye, Daniel Brynolf, Jonas Eriksson, Nicolas Padfield and BARRAGAN.

Demonstrates how to use the Sparkfun RBG LED Matrix backpack showing a small animation made frame by frame. Two types of animation are handled: slide and frame replace.

int bits[8] = { 
  128, 64, 32, 16, 8, 4, 2, 1 };

int clock = 16;  // pin SCK del display
int data = 18;   // pin DI del display
int cs = 19;     // pin CS del display

byte bitmaps[10][8][8];     // Space for 10 frames of 8x8 pixels
byte displayPicture[8][8];  // What is currently ON display.
int currentBitmap = 0;      // current displayed bitmap, per display
int targetBitmap = 1;       // Desired image, for the animation to strive for, per display
int step;                   // animation step, usually from 0 to 8, per screen
int stepDelay = 19;         // the wait time between each animation frame
unsigned int delayCounter;           // holder for the delay, as to not hog to processor, per screen
int animationStyle = 0;     // different types of animation 0 = slide 1 = frame replace
unsigned long lastTime;     // display refresh time

void setup() {
  Serial.begin(115200);  // used for debug

  matrixInit();
  int bitmap = 0;

  // black color for buildings 0
  // sky rotating color 1-7
  
  // bitmap 0
  addLineTobitmap(bitmap,0,1,1,1,1,0,1,1,1);
  addLineTobitmap(bitmap,1,1,1,1,1,0,0,1,1);
  addLineTobitmap(bitmap,2,1,1,1,1,0,0,1,1);
  addLineTobitmap(bitmap,3,1,1,1,1,0,0,1,0);
  addLineTobitmap(bitmap,4,1,0,1,0,0,0,1,0);
  addLineTobitmap(bitmap,5,1,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 1
  bitmap++;
  addLineTobitmap(bitmap,0,2,2,2,2,0,2,2,2);
  addLineTobitmap(bitmap,1,2,2,2,2,0,0,2,2);
  addLineTobitmap(bitmap,2,2,2,2,2,0,0,2,2);
  addLineTobitmap(bitmap,3,2,2,2,2,0,0,2,0);
  addLineTobitmap(bitmap,4,2,0,2,0,0,0,2,0);
  addLineTobitmap(bitmap,5,2,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 2
  bitmap++;
  addLineTobitmap(bitmap,0,3,3,3,3,0,3,3,3);
  addLineTobitmap(bitmap,1,3,3,3,3,0,0,3,3);
  addLineTobitmap(bitmap,2,3,3,3,3,0,0,3,3);
  addLineTobitmap(bitmap,3,3,3,3,3,0,0,3,0);
  addLineTobitmap(bitmap,4,3,0,3,0,0,0,3,0);
  addLineTobitmap(bitmap,5,3,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 3
  bitmap++;
  addLineTobitmap(bitmap,0,4,4,4,4,0,4,4,4);
  addLineTobitmap(bitmap,1,4,4,4,4,0,0,4,4);
  addLineTobitmap(bitmap,2,4,4,4,4,0,0,4,4);
  addLineTobitmap(bitmap,3,4,4,4,4,0,0,4,0);
  addLineTobitmap(bitmap,4,4,0,4,0,0,0,4,0);
  addLineTobitmap(bitmap,5,4,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 4
  bitmap++;
  addLineTobitmap(bitmap,0,5,5,5,5,0,5,5,5);
  addLineTobitmap(bitmap,1,5,5,5,5,0,0,5,5);
  addLineTobitmap(bitmap,2,5,5,5,5,0,0,5,5);
  addLineTobitmap(bitmap,3,5,5,5,5,0,0,5,0);
  addLineTobitmap(bitmap,4,5,0,5,0,0,0,5,0);
  addLineTobitmap(bitmap,5,5,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 5
  bitmap++;
  addLineTobitmap(bitmap,0,6,6,6,6,0,6,6,6);
  addLineTobitmap(bitmap,1,6,6,6,6,0,0,6,6);
  addLineTobitmap(bitmap,2,6,6,6,6,0,0,6,6);
  addLineTobitmap(bitmap,3,6,6,6,6,0,0,6,0);
  addLineTobitmap(bitmap,4,6,0,6,0,0,0,6,0);
  addLineTobitmap(bitmap,5,6,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 6
  bitmap++;
  addLineTobitmap(bitmap,0,7,7,7,7,0,7,7,7);
  addLineTobitmap(bitmap,1,7,7,7,7,0,0,7,7);
  addLineTobitmap(bitmap,2,7,7,7,7,0,0,7,7);
  addLineTobitmap(bitmap,3,7,7,7,7,0,0,7,0);
  addLineTobitmap(bitmap,4,7,0,7,0,0,0,7,0);
  addLineTobitmap(bitmap,5,7,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  // bitmap 7
  bitmap++;
  addLineTobitmap(bitmap,0,1,1,1,1,0,1,1,1);
  addLineTobitmap(bitmap,1,1,1,1,1,0,0,1,1);
  addLineTobitmap(bitmap,2,1,1,1,1,0,0,1,1);
  addLineTobitmap(bitmap,3,1,1,1,1,0,0,1,0);
  addLineTobitmap(bitmap,4,1,0,1,0,0,0,1,0);
  addLineTobitmap(bitmap,5,1,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,6,0,0,0,0,0,0,0,0);
  addLineTobitmap(bitmap,7,0,0,0,0,0,0,0,0);

  currentBitmap = 7;
  targetBitmap = 7;
  lastTime = millis();
}

void loop() {
  if(currentBitmap == targetBitmap) {
    targetBitmap++;
    targetBitmap%=8;  // there are 8 frames, from 0 to 7
  }

  if((millis() - lastTime) > 70) {
    handleAnimations();
    lastTime = millis();
    Serial.print("currentBitmap: ");
    Serial.print(currentBitmap);
    Serial.print(" targetBitmap: ");
    Serial.println(targetBitmap);
  }
  drawFrame(displayPicture);
}

void drawFrame(byte frame[8][8]) {
  digitalWrite(clock, LOW);  //sets the clock for each display, running through 0 then 1
  digitalWrite(data, LOW);   //ditto for data.
  delayMicroseconds(10);
  digitalWrite(cs, LOW);     //ditto for cs.
  delayMicroseconds(10);
  for(int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      //Drawing the grid. x across then down to next y then x across.
      writeByte(frame[x][y]);  
      delayMicroseconds(10);
    }
  }
  delayMicroseconds(10);
  digitalWrite(cs, HIGH);
}

// prints out bytes. Each colour is printed out.
void writeByte(byte myByte) {
  for (int b = 0; b < 8; b++) {  // converting it to binary from colour code.
    digitalWrite(clock, LOW); 
    if ((myByte & bits[b])  > 0) {
      digitalWrite(data, HIGH);
    } 
    else {
      digitalWrite(data, LOW);
    }
    digitalWrite(clock, HIGH); 
    delayMicroseconds(10);
    digitalWrite(clock, LOW); 
  }
}

void matrixInit() {
  pinMode(clock, OUTPUT); // sets the digital pin as output 
  pinMode(data, OUTPUT); 
  pinMode(cs, OUTPUT); 
}

void handleAnimations() {      
  if(currentBitmap != targetBitmap){
    // the function takes 3 variables
    drawAnimationToDisplay(currentBitmap, targetBitmap, step); 
    delayCounter++;
    if(delayCounter > stepDelay){
      step--;
    }
    if(step < 0){
      step = 7;
      currentBitmap = targetBitmap;
    }
  } 
  else {
    drawBitmapToDisplay(currentBitmap); 
  }
}

void drawBitmapToDisplay(int bitmap) {
  for(int x = 0; x < 8; x++) {
    for (int y = 0 ; y < 8; y++) {
      //copies the bitmap to be displayed ( in memory )
      displayPicture[x][y] = bitmaps[bitmap][x][y];
    }
  }    
}

void drawAnimationToDisplay(int bitmap, int targetBitmap, int step) {  
  switch (animationStyle) {
  case 0:   // slide transition
    for(int x = 0; x < 8-step; x++) {
      for (int y = 0 ; y < 8; y++) {
        displayPicture[x][y] = bitmaps[targetBitmap][x+step][y];
      }
    }
    for(int x = 0; x < step ;x++) {
      for (int y = 0 ; y < 8;y++) {
        displayPicture[8-step+x][y] = bitmaps[bitmap][x][y];
      }
    }
    break;
  case 1:  // frame by frame
    for(int x = 0; x < 8; x++) {
      for (int y = 0 ; y < 8; y++) {
        displayPicture[x][y] = bitmaps[bitmap][x][y];
      }
    }
    break;  
  }
}

void addLineTobitmap(int bitmap, int line, byte a,byte b,byte c, byte d, byte e, byte f,byte g, byte h) {
  bitmaps[bitmap][7][line] = a;
  bitmaps[bitmap][6][line] = b;
  bitmaps[bitmap][5][line] = c;
  bitmaps[bitmap][4][line] = d;
  bitmaps[bitmap][3][line] = e;
  bitmaps[bitmap][2][line] = f;
  bitmaps[bitmap][1][line] = g;
  bitmaps[bitmap][0][line] = h;
}