Como usar la memoria EEPROM de tu Arduino UNO

EEPROM.write(0, 9);

EEPROM.read(0);

/*
* Rui Santos
* Complete Project Details https://randomnerdtutorials.com
*/

#include <EEPROM.h>

const int buttonPin = 8; // pushbutton pin
const int ledPin = 4; // LED pin

int ledState; // variable to hold the led state
int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin


// the following variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long lastDebounceTime = 0; // the last time the output pin was toggled
long debounceDelay = 50; // the debounce time; increase if the output flickers

void setup() {
// set input and output
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);

// set initial LED state
digitalWrite(ledPin, ledState);

// initialize serial monitor
Serial.begin (9600);

//check stored LED state on EEPROM using function defined at the end of the code
checkLedState();
}

void loop() {
// read the state of the switch into a local variable
int reading = digitalRead(buttonPin);

if(reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}

if((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer
// than the debounce delay, so take it as the actual current state:

// if the button state has changed:
if(reading != buttonState) {
buttonState = reading;

// only toggle the LED if the new button state is HIGH
if(buttonState == HIGH) {
ledState = !ledState;
}
}
}

// set the LED state
digitalWrite(ledPin, ledState);
// save the current LED state in the EEPROM
EEPROM.update(0, ledState);
// save the reading. Next time through the loop,
// it'll be the lastButtonState
lastButtonState = reading;
}

// Prints and upates the LED state
// when the Arduino board restarts or powers up
void checkLedState() {
Serial.println("LED status after restart: ");
ledState = EEPROM.read(0);
if(ledState == 1) {
Serial.println ("ON");
digitalWrite(ledPin, HIGH);
}
if(ledState == 0) {
Serial.println ("OFF");
digitalWrite(ledPin, LOW);
}
}