EEPROM in Arduino

1024 bytes that survive power loss.

// EEPROM survives power loss: 1024 bytes of remember-me.
#include <EEPROM.h>

const int THRESHOLD_ADDR = 0;

void setup() {
  Serial.begin(9600);
  int saved = EEPROM.read(THRESHOLD_ADDR);
  Serial.print("Saved threshold: ");
  Serial.println(saved);
  // update only writes when the value changed -- cells wear out.
  EEPROM.update(THRESHOLD_ADDR, 180);
}

void loop() {
}

How it works

1. #include <EEPROM.h> brings in the persistent store.
2. EEPROM.read recovers the byte saved last session.
3. update writes only on change — cells wear out.

Keywords and builtins used here

• EEPROM
• Serial
• begin
• const
• int
• loop
• print
• println
• read
• setup
• void

The run, in numbers

Lines

16

Characters to type

362

Tokens

65

Three-star pace

65 tpm

At the three-star pace of 65 tokens a minute, this run takes about 60 seconds.

Type this snippet

Step 3 of 3 in Data, step 21 of 27 in Language basics.

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