ESP8266 EEPROM seems not working, saved data are different when I try to read them

Question

I'm working on project which require to save some data into the EEPROM. As I read online the ESP8266 has no real EEPROM, it use a section of FLASH just after the SPIFFS. Due to this read/write is quite different from standard Arduino, you need to call EEPROM.commit(). You also have to call EEPROM.begin(size) (I used size = 512) before start to use it.

I follow different tutorials online and I made some tests but it seems not working at all. When I try to save a value and then read it, values are different. I tried with

EEPROM.write(..)
...
EEPROM.read(..)

and with

EEPROM.put(..)
...
EEPROM.get(..)

but nothing change.

Is there any configuration on the board I need to set into Arduino IDE/Board Configuration?

EDIT: here's the code

void setup() 
{
    Serial.begin(9600);
    Serial.println();

    EEPROM.begin(512);
    EEPROM.write(0, 62);
    EEPROM.write(10, 103);
    //EEPROM.commit();
    EEPROM.end();
    Serial.print("Read at 0:"); Serial.println(EEPROM.read(0), DEC);
    Serial.print("Read at 10:"); Serial.println(EEPROM.read(10), DEC);
}

I always read 0 in the output.

Answer 1

You can read the emulated EEPROM only between begin and end. It works with memory image.

• begin allocates the in-memory image.
• commit writes it to flash.
• end commits and deletes the memory image.

Answer 2

Here is some ESP8266 example code to store and read strings from EEPROM data:

#include <EEPROM.h>

void writeString(char add,String data);
String read_String(char add);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  EEPROM.begin(512);  // Note::

  String data = "Hello World";

  Serial.print("Writing Data:");
  Serial.println(data);

  writeString(10, data);  //Address 10 and String type data
  delay(10);
}

void loop() {
  // put your main code here, to run repeatedly:
  String recivedData;
  recivedData = read_String(10);
  Serial.print("Read Data:");
  Serial.println(recivedData);
  delay(1000);
}

void writeString(char add,String data)
{
  int _size = data.length();
  int i;
  for(i=0;i<_size;i++)
  {
    EEPROM.write(add+i,data[i]);
  }
  EEPROM.write(add+_size,'\0');   //Add termination null character for String Data
}

String read_String(char add)
{
  int i;
  char data[100]; //Max 100 Bytes
  int len=0;
  unsigned char k;
  k=EEPROM.read(add);
  while(k != '\0' && len<500)   //Read until null character
  {    
    k=EEPROM.read(add+len);
    data[len]=k;
    len++;
  }
  data[len]='\0';
  return String(data);
}