EEPROM read and write string

arduino uno ATmega328P EEPROM read write string

Read and write a word in the EEPROM with a null-terminated string to detect the end of word.

Code

Download code

#include <EEPROM.h>
String greeting = "hello";
int addr = 0;

void setup() {
  Serial.begin(115200);

  Serial.println("");
  Serial.println("");

  Serial.print("Word to write: ");
  Serial.println(greeting);
  Serial.print("Word length to write: ");
  Serial.println(greeting.length());

  // Write to EEPROM
  for (int index = 0; index < greeting.length(); index++) {
    EEPROM.write(addr, greeting[index]);
    delay(10);

    Serial.print("Writing ");
    Serial.print(greeting[index]);
    Serial.print(" in address ");
    Serial.println(addr);

    addr++;
  }

  EEPROM.write(addr, '\0');
  EEPROM.read(addr);

  Serial.println("");
  Serial.println("Begin reading back the array: ");
  int currentAddr = 0;
  char readChar = "";
  String readGreeting = "";

  while (readChar != '\0') {
    Serial.print("Reading ");

    readChar = EEPROM.read(currentAddr);
    delay(10);
    if (readChar != '\0') {
      readGreeting += readChar;
    }

    currentAddr++;

    Serial.print(readChar);
    Serial.print(" in address ");
    Serial.println(currentAddr);
  }

  Serial.print("Final string read from EEPROM: ");
  Serial.println(readGreeting);
}

void loop() {}

Makefile

.PHONY: lint compile upload clean

flash: lint compile upload clean

lint:
	cpplint --extensions=ino --filter=-legal/copyright *.ino

compile:
	arduino-cli compile --fqbn arduino:avr:uno ./

upload:
	arduino-cli upload -p /dev/cu.usbmodem14* --fqbn arduino:avr:uno ./

clean:
	rm -f .*.hex
	rm -f .*.elf

Serial console

Serial output from the firmware.

References

EEPROM Write tutorial