int led =10;
int btn=A2;
int btnsta=HIGH;
int ledsta=HIGH;
int btnlast= HIGH;
void setup(){
  pinMode(led, OUTPUT);
  pinMode(btn, INPUT);
}
void loop(){
  // 
  btnsta=digitalRead(btn);
  // quy định khi nhấn nút 
   if(btnsta==HIGH){
    digitalWrite(led,HIGH);
  }else{
     digitalWrite(led,LOW);
   }

}