#define CORRECT_CLOCK 8
void fixDelay(uint32_t ms) {
  delay(ms << CORRECT_CLOCK);
}
void setup() {
  pinMode(13, 1);
  // Pins D5 and D6 - 4 kHz
  TCCR0B = 0b00000010; // x8
  TCCR0A = 0b00000001; // phase correct
}
void loop() {
  digitalWrite(13, !digitalRead(13));
  fixDelay(1000);
}