#define BP 2
#define LED 13

void setup() {
 pinMode(BP, INPUT_PULLUP);
 pinMode(LED,OUTPUT);
 Serial.begin(9600);
}

bool WAS_PRESSED = false;
void loop() {
 bool pressed = !digitalRead(BP);
 if (!pressed && WAS_PRESSED){
 digitalWrite(LED, !digitalRead(LED));
 }

 WAS_PRESSED = pressed;

}