EEPROM Library

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1#include <EEPROM.h>

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1EEPROM.read(address)

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1#include <EEPROM.h>
2
3int a = 0;
4int value;
5
6void setup()
7{
8  Serial.begin(9600);
9}
10
11void loop()
12{
13  value = EEPROM.read(a);
14
15  Serial.print(a);
16  Serial.print("\t");
17  Serial.print(value);
18  Serial.println();
19
20  a = a + 1;
21
22  if (a == 512)
23    a = 0;
24
25  delay(500);
26}

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1EEPROM.write(address, value)

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1#include <EEPROM.h>
2
3void setup()
4{
5  for (int i = 0; i < 255; i++)
6    EEPROM.write(i, i);
7}
8
9void loop()
10{
11}

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1EEPROM.update(address, value)

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1#include <EEPROM.h>
2
3void setup()
4{
5  for (int i = 0; i < 255; i++) {
6    // this performs as EEPROM.write(i, i)
7    EEPROM.update(i, i);
8  }
9  for (int i = 0; i < 255; i++) {
10    // write value "12" to cell 3 only the first time
11    // will not write the cell the remaining 254 times
12    EEPROM.update(3, 12);
13  }
14}
15
16void loop()
17{
18}

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1EEPROM.get(address, data)

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1#include <EEPROM.h>
2
3struct MyObject{
4  float field1;
5  byte field2;
6  char name[10];
7};
8
9void setup(){
10
11  float f = 0.00f;   //Variable to store data read from EEPROM.
12  int eeAddress = 0; //EEPROM address to start reading from
13
14  Serial.begin( 9600 );
15  while (!Serial) {
16    ; // wait for serial port to connect. Needed for Leonardo only
17  }
18  Serial.print( "Read float from EEPROM: " );
19
20  //Get the float data from the EEPROM at position 'eeAddress'
21  EEPROM.get( eeAddress, f );
22  Serial.println( f, 3 );  //This may print 'ovf, nan' if the data inside the EEPROM is not a valid float.
23
24  // get() can be used with custom structures too.
25  eeAddress = sizeof(float); //Move address to the next byte after float 'f'.
26  MyObject customVar; //Variable to store custom object read from EEPROM.
27  EEPROM.get( eeAddress, customVar );
28
29  Serial.println( "Read custom object from EEPROM: " );
30  Serial.println( customVar.field1 );
31  Serial.println( customVar.field2 );
32  Serial.println( customVar.name );
33}
34
35void loop(){ /* Empty loop */ }

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1EEPROM.put(address, data)

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1#include <EEPROM.h>
2
3struct MyObject {
4  float field1;
5  byte field2;
6  char name[10];
7};
8
9void setup() {
10
11  Serial.begin(9600);
12  while (!Serial) {
13    ; // wait for serial port to connect. Needed for native USB port only
14  }
15
16  float f = 123.456f;  //Variable to store in EEPROM.
17  int eeAddress = 0;   //Location we want the data to be put.
18
19
20  //One simple call, with the address first and the object second.
21  EEPROM.put(eeAddress, f);
22
23  Serial.println("Written float data type!");
24
25  /** Put is designed for use with custom structures also. **/
26
27  //Data to store.
28  MyObject customVar = {
29    3.14f,
30    65,
31    "Working!"
32  };
33
34  eeAddress += sizeof(float); //Move address to the next byte after float 'f'.
35
36  EEPROM.put(eeAddress, customVar);
37  Serial.print("Written custom data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");
38}
39
40void loop() {   /* Empty loop */ }

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1EEPROM[address]

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1#include <EEPROM.h>
2
3void setup(){
4
5  unsigned char val;
6
7  //Read first EEPROM cell.
8  val = EEPROM[ 0 ];
9
10  //Write first EEPROM cell.
11  EEPROM[ 0 ] = val;
12
13  //Compare contents
14  if( val == EEPROM[ 0 ] ){
15    //Do something...
16  }
17}
18
19void loop(){ /* Empty loop */ }

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1EEPROM.length()