#include <avr/eeprom.h>
 
const int buttonPin = 2;
 
int buttonState = 0;
 
struct settings_t
{
  long alarm;
  int mode;
} settings;
 
void setup()
{
  eeprom_read_block((void*)&settings, (void*)0, sizeof(settings));
    // ...
}
void loop()
{
   
    buttonState = digitalRead(buttonPin);  
 
    // let the user adjust their alarm settings
    // let the user adjust their mode settings
    // ...
    settings.mode = analogRead(A0);  // potentiometer on A0
    // if they push the "Save" button, save their configuration
    if (buttonState == HIGH)  // button attached on digital pin 2
      eeprom_write_block((const void*)&settings, (void*)0, sizeof(settings));
}