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

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My Robot Education Sdn. Bhd. (Robotedu.my) was founded in 2015 as the first robotics education centre in Malaysia to provide Arduino-based robotics courses for youths. Our vision is to be able to provide robotics education to every youth in Malaysia.