Fast 8x8 LED dot matrix + SN74HC595 + Arduino Uno R3 counter

matrix.fzz

matrix.ino

inline void activateCol(byte n)   __attribute__((always_inline));
inline void setbit(byte value)    __attribute__((always_inline));
inline void shift()               __attribute__((always_inline));
inline void latch()               __attribute__((always_inline));
inline void clear()               __attribute__((always_inline));

byte buffer[8];


void setup() {
  DDRD |= B11111100;
  DDRB |= B00111111;
  PORTD = (PORTD & B00000011) | B11100000;
  PORTB = (PORTB & B11000000) | B00111111;
  TIMSK0 = 0;
  clear();
}

void loop() {  
  for (unsigned long counter = 0; counter < 0xFFFFFFFF; counter++) {
    *((long*)buffer) = counter;
    draw(buffer);
  }
  
}

  ////////////////////////
 // LED MATRIX HELPERS //
////////////////////////


//
// Optimized block draw
//


inline void draw(const byte *data) {
  setbit(true);
  shift();
  setbit(false);
  for (byte row = 0; row < 8; row++) {
    byte arr = data[row];
    latch();
    for (int col = 1; col < 0x200; col <<= 1) {
      bool on = arr & 0x1;
      arr >>= 1;
      activateCol(on ? col : 0x0);
    }
    shift();
  }
  //latch();
}

//
// Direct addressing
//

inline void activateCol(byte n) {
  byte val = ~n;
  PORTD = PORTD & B00011111 | (val << 5);
  PORTB = PORTB & B11100000 | (val >> 3);
}

  ////////////////////////////
 // SHIFT REGISTER CONTROL //
////////////////////////////

inline void setbit(bool value) {
  PORTD = PORTD & B11111011 | (value << 2);
}

inline void shift() {
  PORTD |= B00010000;
  PORTD &= B11101111;
}

inline void latch() {
  PORTD |= B00001000;
  PORTD &= B11110111;
}

inline void clear() {
  PORTB &= B11011111;
  PORTB |= B00100000;
}