int B_pin = 8; //Khai bao chan nut bam button
long TDT, TDHT; //Khai bao khoang thoi gian
float KTG;
void setup() {
  // put your setup code here, to run once:
pinMode(B_pin, INPUT_PULLUP);
Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
if(digitalRead(B_pin) == 0){
  while(digitalRead(B_pin) == 0) { //delay de
    delay(10);
  }
  TDHT = millis();
  KTG = (float)(TDHT - TDT)/1000; //float giup hien thi 2 so thap phan sau dau phay vi TDHT va TDT la so nguyen
  Serial.print("KTG between two presses: ");
  Serial.print(KTG);
  Serial.print("\n");
  TDT = TDHT;
}
}