#define btn1 2
bool btnstate1=0;
bool btnprevstate1=0;
void setup() {
Serial.begin(115200);
pinMode(LED_BUILTIN, OUTPUT);
pinMode(btn1, INPUT);
Serial.println("Start Program");
}

static double ti=3000;           // time interval
//  static double pvtime=millis();  // previous time
static double pvtime=0 ;  // previous time
double elaps=0;
void loop() {

  if(digitalRead(btn1) == HIGH){
    btnprevstate1 =1;
        checktray1();
  }
  else{
    btnprevstate1=0;
    
  }
Serial.print("Button 1 Prev =");
Serial.println(btnprevstate1);
Serial.print("pvtime =");
Serial.println(pvtime);
}

void checktray1(){
  btnstate1=digitalRead(btn1);
  if(btnprevstate1 =1){
    //digitalWrite(LED_BUILTIN,HIGH);
    elaps=millis()-pvtime;   // elaps time
    if (elaps>=ti){
       //pvtime=(millis()+ti-elaps);
       elaps=millis()-ti;
       digitalWrite(LED_BUILTIN,LOW);
       //Serial.println(countDown);
     } 
     else{
    digitalWrite(LED_BUILTIN,HIGH);  
     }
   }
  else {
     pvtime=millis();
     //digitalWrite(LED_BUILTIN,HIGH);
  }
   Serial.print("pvtime=");
   Serial.println(pvtime);
   
   Serial.print("elaps=");
   Serial.println(elaps);
}