#include <SoftwareSerial.h>
#define rxPin 0
#define txPin 1

SoftwareSerial Serial(rxPin, txPin);

int pressLength = 0; //the value for how long the button is pushed down  
 
int One = 100; //define the *minimum* length of time, in milli-seconds, that the button must be pressed for a particular option to occur

int buttonPin = 3; // button is on pin 3

void setup() {
  
  pinMode(rxPin, INPUT); //rx is the input
  pinMode(txPin, OUTPUT); //tx is the output
  pinMode(buttonPin, INPUT_PULLUP); //the button is a input pullup (to activate internal resistor)

  Serial.begin(9600); 
}

void loop(){

  while (digitalRead(buttonPin) == LOW ){ 
 
    delay(100);  
    pressLength = pressLength + 100;   
}

 if (pressLength >= One){
        
    Serial.println(pressLength);
  }
  
 pressLength = 0; //reset the pressLength every loop 

}