Heart on a bare 8x8 matrix, on an Arduino Uno

// A bare 8x8 LED matrix, no driver chip: sixteen pins, one row at a time.
//
//   1088AS: rows R1..R8 are the cathodes, columns C1..C8 the anodes
//   columns C1..C8 -> pins 2 to 9, each through its own 220 ohm
//   rows R1..R8    -> pins 10, 11, 12, 13, A0, A1, A2, A3
//
// A row is selected by pulling it LOW; a dot in it lights when its column is
// HIGH. Only one row is ever on, for two milliseconds, so each column pin
// carries one LED's current and the whole picture is redrawn about 60 times
// a second. The eye does the rest.

const uint8_t COLUMN_PINS[8] = {2, 3, 4, 5, 6, 7, 8, 9};
const uint8_t ROW_PINS[8] = {10, 11, 12, 13, A0, A1, A2, A3};

// One byte a row, the left column in the top bit.
const uint8_t BIG[8] = {0x00, 0x66, 0xFF, 0xFF, 0xFF, 0x7E, 0x3C, 0x18};
const uint8_t SMALL[8] = {0x00, 0x00, 0x24, 0x7E, 0x7E, 0x3C, 0x18, 0x00};

void drawFor(const uint8_t *picture, unsigned long ms) {
  unsigned long start = millis();
  while (millis() - start < ms) {
    for (uint8_t r = 0; r < 8; r++) {
      for (uint8_t c = 0; c < 8; c++) digitalWrite(COLUMN_PINS[c], (picture[r] >> (7 - c)) & 1);
      digitalWrite(ROW_PINS[r], LOW);
      delay(2);
      digitalWrite(ROW_PINS[r], HIGH);
    }
  }
}

void setup() {
  for (uint8_t i = 0; i < 8; i++) {
    pinMode(COLUMN_PINS[i], OUTPUT);
    pinMode(ROW_PINS[i], OUTPUT);
    digitalWrite(ROW_PINS[i], HIGH);  // every row off
  }
}

void loop() {
  drawFor(BIG, 400);
  drawFor(SMALL, 250);
  delay(150);  // dark between beats
}