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int x = 12;     // binary: 1100
int y = 10;     // binary: 1010
int z = x ^ y;  // binary: 0110, or decimal 6

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// Note: This code uses registers specific to AVR microcontrollers (Uno, Nano, Leonardo, Mega, etc.)
// it will not compile for other architectures
void setup() {
  DDRB = DDRB | 0b00100000;  // set PB5 (pin 13 on Uno/Nano, pin 9 on Leonardo/Micro, pin 11 on Mega) as OUTPUT
  Serial.begin(9600);
}

void loop() {
  PORTB = PORTB ^ 0b00100000;  // invert PB5, leave others untouched
  delay(100);
}