EEPROM Update

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

The purpose of this example is to show the EEPROM.update() method that writes data only if it is different from the previous content of the locations to be written. This solution may save execution time because every write operation takes 3.3 ms; the EEPROM has also a limit of 100.000 write cycles per single location, therefore avoiding rewriting the same value in any location will increase the EEPROM overall life.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_update

Click press the "upload" button (see the button with right arrow mark).

/***
EEPROM Update method Stores values read from analog input 0 into the EEPROM.
These values will stay in the EEPROM when the board is
turned off and may be retrieved later by another sketch. If a value has not changed in the EEPROM, it is not overwritten
which would reduce the life span of the EEPROM unnecessarily. Released using MIT licence.
***/ #include <EEPROM.h> /** the current address in the EEPROM (i.e. which byte we're going to write to next) **/
int address = 0; void setup() {
/** EMpty setup **/
} void loop() {
/***
need to divide by 4 because analog inputs range from
0 to 1023 and each byte of the EEPROM can only hold a
value from 0 to 255.
***/
int val = analogRead(0) / 4; /***
Update the particular EEPROM cell.
these values will remain there when the board is
turned off.
***/
EEPROM.update(address, val); /***
The function EEPROM.update(address, val) is equivalent to the following: if( EEPROM.read(address) != val ){
EEPROM.write(address, val);
}
***/ /***
Advance to the next address, when at the end restart at the beginning. Larger AVR processors have larger EEPROM sizes, E.g:
- Arduno Duemilanove: 512b EEPROM storage.
- Arduino Uno: 1kb EEPROM storage.
- Arduino Mega: 4kb EEPROM storage. Rather than hard-coding the length, you should use the pre-provided length function.
This will make your code portable to all AVR processors.
***/
address = address + 1;
if (address == EEPROM.length()) {
address = 0;
} /***
As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an
EEPROM address is also doable by a bitwise and of the length - 1. ++address &= EEPROM.length() - 1;
***/ delay(100);
}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMUpdate

EEPROM EEPROM Update library

EEPROM Put

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

The purpose of this example is to show the EEPROM.put() method that writes data on EEPROM using also the EEPROM.update() that writes data only if it is different from the previous content of the locations to be written. The number of bytes written is related to the datatype or custom structure of the variable to be written.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_put

Click press the "upload" button (see the button with right arrow mark).

/***
eeprom_put example. This shows how to use the EEPROM.put() method.
Also, this sketch will pre-set the EEPROM data for the
example sketch eeprom_get. Note, unlike the single byte version EEPROM.write(),
the put method will use update semantics. As in a byte
will only be written to the EEPROM if the data is actually
different. Written by Christopher Andrews 2015
Released under MIT licence.
***/ #include <EEPROM.h> struct MyObject {
float field1;
byte field2;
char name[10];
}; void setup() { Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
} float f = 123.456f; //Variable to store in EEPROM.
int eeAddress = 0; //Location we want the data to be put. //One simple call, with the address first and the object second.
EEPROM.put(eeAddress, f); Serial.println("Written float data type!"); /** Put is designed for use with custom structures also. **/ //Data to store.
MyObject customVar = {
3.14f,
65,
"Working!"
}; eeAddress += sizeof(float); //Move address to the next byte after float 'f'. EEPROM.put(eeAddress, customVar);
Serial.print("Written custom data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");
} void loop() {
/* Empty loop */
}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMPut

EEPROM EEPROM Put library

EEPROM Iterations

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

The purpose of this example is to show how to go through the whole EEPROM memory space with different approaches. The code provided doesn’t run on its own but should be used as a surce of code snippets to be used elsewhere.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_read

Click press the "upload" button (see the button with right arrow mark).

/***
eeprom_iteration example. A set of example snippets highlighting the
simplest methods for traversing the EEPROM. Running this sketch is not necessary, this is
simply highlighting certain programming methods. Written by Christopher Andrews 2015
Released under MIT licence.
***/ #include <EEPROM.h> void setup() { /***
Iterate the EEPROM using a for loop.
***/ for (int index = 0 ; index < EEPROM.length() ; index++) { //Add one to each cell in the EEPROM
EEPROM[ index ] += 1;
} /***
Iterate the EEPROM using a while loop.
***/ int index = 0; while (index < EEPROM.length()) { //Add one to each cell in the EEPROM
EEPROM[ index ] += 1;
index++;
} /***
Iterate the EEPROM using a do-while loop.
***/ int idx = 0; //Used 'idx' to avoid name conflict with 'index' above. do { //Add one to each cell in the EEPROM
EEPROM[ idx ] += 1;
idx++;
} while (idx < EEPROM.length()); } //End of setup function. void loop() {}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMIteration

EEPROM EEPROM Iterations library

EEPROM Get

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

The purpose of this example is to show how the put and get methods provide a different behaviour than write and read, that work on single bytes. Getting different variables from EEPROM retrieve a number of bytes that is related to the variable datatype.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_get

Click press the "upload" button (see the button with right arrow mark).

/***
eeprom_get example. This shows how to use the EEPROM.get() method. To pre-set the EEPROM data, run the example sketch eeprom_put.
This sketch will run without it, however, the values shown
will be shown from what ever is already on the EEPROM. This may cause the serial object to print out a large string
of garbage if there is no null character inside one of the strings
loaded. Written by Christopher Andrews 2015
Released under MIT licence.
***/ #include <EEPROM.h> void setup() { float f = 0.00f; //Variable to store data read from EEPROM.
int eeAddress = 0; //EEPROM address to start reading from Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.print("Read float from EEPROM: "); //Get the float data from the EEPROM at position 'eeAddress'
EEPROM.get(eeAddress, f);
Serial.println(f, 3); //This may print 'ovf, nan' if the data inside the EEPROM is not a valid float. /***
As get also returns a reference to 'f', you can use it inline.
E.g: Serial.print( EEPROM.get( eeAddress, f ) );
***/ /***
Get can be used with custom structures too.
I have separated this into an extra function.
***/ secondTest(); //Run the next test.
} struct MyObject {
float field1;
byte field2;
char name[10];
}; void secondTest() {
int eeAddress = sizeof(float); //Move address to the next byte after float 'f'. MyObject customVar; //Variable to store custom object read from EEPROM.
EEPROM.get(eeAddress, customVar); Serial.println("Read custom object from EEPROM: ");
Serial.println(customVar.field1);
Serial.println(customVar.field2);
Serial.println(customVar.name);
} void loop() {
/* Empty loop */
}  

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMGet

EEPROM EEPROM Get library

EEPROM CRC

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

A CRC is a simple way of checking whether data has changed or become corrupted. This example calculates a CRC value directly on the EEPROM values. This CRC is like a signature and any change in the calculated CRC means a change in the stored data. The purpose of this example is to highlight how the EEPROM object can be used just like an array.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_crc

Click press the "upload" button (see the button with right arrow mark).

/***
Written by Christopher Andrews.
CRC algorithm generated by pycrc, MIT licence ( https://github.com/tpircher/pycrc ). A CRC is a simple way of checking whether data has changed or become corrupted.
This example calculates a CRC value directly on the EEPROM values.
The purpose of this example is to highlight how the EEPROM object can be used just like an array.
***/ #include <Arduino.h>
#include <EEPROM.h> void setup() { //Start serial
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
} //Print length of data to run CRC on.
Serial.print("EEPROM length: ");
Serial.println(EEPROM.length()); //Print the result of calling eeprom_crc()
Serial.print("CRC32 of EEPROM data: 0x");
Serial.println(eeprom_crc(), HEX);
Serial.print("\n\nDone!");
} void loop() {
/* Empty loop */
} unsigned long eeprom_crc(void) { const unsigned long crc_table[16] = {
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
}; unsigned long crc = ~0L; for (int index = 0 ; index < EEPROM.length() ; ++index) {
crc = crc_table[(crc ^ EEPROM[index]) & 0x0f] ^ (crc >> 4);
crc = crc_table[(crc ^ (EEPROM[index] >> 4)) & 0x0f] ^ (crc >> 4);
crc = ~crc;
}
return crc;
}  

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMCrc 

EEPROM EEPROM CRC library

EEPROM Write

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

This example illustrates how to store values read from analog input 0 into the EEPROM using the EEPROM.write() function. These values will stay in the EEPROM when the board is turned off and may be retrieved later by another sketch.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_write

Click press the "upload" button (see the button with right arrow mark).

 

/* * EEPROM Write
*
* Stores values read from analog input 0 into the EEPROM.
* These values will stay in the EEPROM when the board is
* turned off and may be retrieved later by another sketch.
*/ #include <EEPROM.h> /** the current address in the EEPROM (i.e. which byte we're going to write to next) **/
int addr = 0; void setup() {
/** Empty setup. **/
} void loop() {
/***
Need to divide by 4 because analog inputs range from
0 to 1023 and each byte of the EEPROM can only hold a
value from 0 to 255.
***/ int val = analogRead(0) / 4; /***
Write the value to the appropriate byte of the EEPROM.
these values will remain there when the board is
turned off.
***/ EEPROM.write(addr, val); /***
Advance to the next address, when at the end restart at the beginning. Larger AVR processors have larger EEPROM sizes, E.g:
- Arduno Duemilanove: 512b EEPROM storage.
- Arduino Uno: 1kb EEPROM storage.
- Arduino Mega: 4kb EEPROM storage. Rather than hard-coding the length, you should use the pre-provided length function.
This will make your code portable to all AVR processors.
***/
addr = addr + 1;
if (addr == EEPROM.length()) {
addr = 0;
} /***
As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an
EEPROM address is also doable by a bitwise and of the length - 1. ++addr &= EEPROM.length() - 1;
***/ delay(100);
}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMWrite

EEPROM EEPROM Write library

EEPROM Read

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

This example illustrates how to read the value of each byte EEPROM using the EEPROM.read() function, and how to print those values to the serial window of the Arduino Software (IDE).

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_read

Click press the "upload" button (see the button with right arrow mark).

/*
* EEPROM Read
*
* Reads the value of each byte of the EEPROM and prints it
* to the computer.
* This example code is in the public domain.
*/ #include <EEPROM.h> // start reading from the first byte (address 0) of the EEPROM
int address = 0;
byte value; void setup() {
// initialize serial and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
} void loop() {
// read a byte from the current address of the EEPROM
value = EEPROM.read(address); Serial.print(address);
Serial.print("\t");
Serial.print(value, DEC);
Serial.println(); /***
Advance to the next address, when at the end restart at the beginning. Larger AVR processors have larger EEPROM sizes, E.g:
- Arduno Duemilanove: 512b EEPROM storage.
- Arduino Uno: 1kb EEPROM storage.
- Arduino Mega: 4kb EEPROM storage. Rather than hard-coding the length, you should use the pre-provided length function.
This will make your code portable to all AVR processors.
***/
address = address + 1;
if (address == EEPROM.length()) {
address = 0;
} /***
As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an
EEPROM address is also doable by a bitwise and of the length - 1. ++address &= EEPROM.length() - 1;
***/ delay(500);
}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMRead

EEPROM EEPROM Read library

EEPROM Clear

The microcontroller on the Arduino have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

This example illustrates how to set of all of those bytes to 0, initializing them to hold new information, using the EEPROM.write() function.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_clear

Click press the "upload" button (see the button with right arrow mark).

/*
* EEPROM Clear
*
* Sets all of the bytes of the EEPROM to 0.
* Please see eeprom_iteration for a more in depth
* look at how to traverse the EEPROM.
*
* This example code is in the public domain.
*/ #include <EEPROM.h> void setup() {
// initialize the LED pin as an output.
pinMode(13, OUTPUT);

/***
Iterate through each byte of the EEPROM storage. Larger AVR processors have larger EEPROM sizes, E.g:
- Arduno Duemilanove: 512b EEPROM storage.
- Arduino Uno: 1kb EEPROM storage.
- Arduino Mega: 4kb EEPROM storage. Rather than hard-coding the length, you should use the pre-provided length function.
This will make your code portable to all AVR processors.
***/ for (int i = 0 ; i < EEPROM.length() ; i++) {
EEPROM.write(i, 0);
} // turn the LED on when we're done
digitalWrite(13, HIGH);
} void loop() {
/** Empty loop. **/
}

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMClear

EEPROM EEPROM Clear library