Clearing EEPROM

Question

I'm trying to clear my EEPROM and am using this code:

#include <EEPROM.h>
void setup()
{
// write a 0 to all 4096 bytes of the EEPROM
for (int i = 0; i < 4096; i++)
EEPROM.write(i, 0);

delay(9999999);
}

void loop()
{
}

I don't see a problem with it but it is ineffective. Am I missing something?

Answer 1

The tutorial here is very clear about how to clear the contents of the Atmel's EEPROM. I only see 2 major difference. The tutorial finds the size of the EEPROM through a function call. Probably much safer. And there is no call to a delay() function.

The tutorial does include lighting up an LED when finished. And @Edgar Bonet is correct that erasing an EEPROM (altering each floating gate with in the chip) does take time. And you have no way to known when the EEPROM clearing is finished in your code.

It is possible you are forcing your code to stop before it is finished. In which case it would appear the EEPROM is not completely cleared.

Answer 2

Thank you all for helping me out. This is what I ended up using (ESP8266 1.0 12E with Arduino IDE):

#include <EEPROM.h>
#include <ESP8266WiFi.h>

void setup()
{
  Serial.begin(115200);
  EEPROM.begin(512);
  delay(5000);
  Serial.println("clearing EEPROM...");
  // write a 0 to first 1000 bytes of the EEPROM
  for (int i = 0; i < 1000; ++i) {
    EEPROM.write(i, -1);
 }
  EEPROM.commit();
  delay(5000);
  Serial.println("Reading EEPROM ssid");
  String esid;
  for (int i = 0; i < 64; ++i)
  {
    esid += char(EEPROM.read(i));
  }
  Serial.print("SSID: ");
  Serial.println(esid);
  Serial.println("Reading EEPROM pass");
  String epass = "";
  for (int i = 64; i < 128; ++i)
  {
    epass += char(EEPROM.read(i));
  }
  Serial.print("PASS: ");
  Serial.println(epass);
}

void loop()
{
}

It's probably longer than it has to be but I pulled stuff from other sketches I've worked on and prioritize function over form. This writes a "-1" to the first 1000 bytes and then prints the first 128 bytes. Since I am only concerned about the first 50 bytes or so this was sufficient for my needs.