     Serial.println(prompt);
     while (!Serial.available());
   }
-  
+
   return Serial.parseInt();
 }
 

// DS3231:  SDA pin   -> Arduino Digital 20 (SDA) or the dedicated SDA1 (Digital 70) pin
//          SCL pin   -> Arduino Digital 21 (SCL) or the dedicated SCL1 (Digital 71) pin

#include <DS3231.h>
#include <SPI.h>
#include <SD.h>

#define SD_PIN 4
#define KEY_FILE "key.txt"

DS3231 rtc(SDA, SCL);
String key = "";

// Gets a UNIX timestamp from the RTC
long getTimestamp() {

void setup() {
  // Set up the serial terminal
  Serial.begin(115200);

  // Set up the button
  pinMode(BUTTON_PIN, INPUT);

  // Set up the real time clock
  rtc.begin();

  // Set up the SD card
  pinMode(10, OUTPUT);
  if (!SD.begin(SD_PIN)) {
