// Test fastDigital function timing with a scope.
#include <DigitalIO.h>
const uint8_t PIN = 13;
void setup() {
  fastPinMode(PIN, OUTPUT);
}
void loop() {
  fastDigitalWrite(PIN, HIGH);
  fastDigitalWrite(PIN, LOW);
  fastDigitalToggle(PIN);
  fastDigitalToggle(PIN);
  delay(1);
}