Pulse and frequency counting using direct input on Timer1

Other Hardware Science and Measurement
2

svenkarlsen:
I would really appreciate if someone with an instrument would take the time to load the following few lines of code on a "naked" Uno, and report what the output frequency is:

void loop() {

PORTD = B00100000; // sets digital pin 5 HIGH
  PORTD = B00000000; // sets digital pin 5 LOW
}

1.066666MHz

void loop() {
  while (true)
  {
    PORTD = B00100000; // sets digital pin 5 HIGH
    PORTD = B00000000; // sets digital pin 5 LOW
  }
}

[/quote]
4.0000MHz

void loop() {
  while (true)
  {
    PORTD = B00100000; // sets digital pin 5 HIGH
    PORTD = B00000000; // sets digital pin 5 LOW
    PORTD = B00100000; // sets digital pin 5 HIGH
    PORTD = B00000000; // sets digital pin 5 LOW
    PORTD = B00100000; // sets digital pin 5 HIGH
    PORTD = B00000000; // sets digital pin 5 LOW
    PORTD = B00100000; // sets digital pin 5 HIGH
    PORTD = B00000000; // sets digital pin 5 LOW
  }
}

[/quote]
6.40000MHz