ESP32 - EEPROM Size

ESP32 - Read EEPROM Size

The EEPROM is one type of Non-Volatile Memories(NVM), which means the data stored in it doesn’t get lost even after the board is turned off.

The ESP32 microcontroller has a Flash memory area that can be interfaced with Arduino EEPROM libraries using a sector (4 kilobytes) of flash memory. The total flash memory size for most of the modules is 4MB, but some board will have 8MB or 16 MB

Step 1: Connect Board to Laptop

Step 2: ESP32 EEPROM size Example Code

Select boar ESP32 DEV Module from Tools >> Boards menu, then select appropriate com port. Upload this program to ESP32.

#include <Wire.h>

#define I2C_SDA_PIN 23

#define I2C_SCL_PIN 19

void eepromSize() {

Serial.println("Discovering eeprom sizes 0x50..0x57");

uint8_t adr = 0x50, i;

uint16_t size;

char buf[64];

while (adr < 0x58) {

i = 0;

size = 0x1000; // Start at 4k

i += sprintf_P(&buf[i], PSTR("0x%02X: "), adr);

if (i2cReady(adr)) { // EEPROM success

uint8_t zeroByte;

Wire.beginTransmission(adr);

Wire.write((uint8_t)0);

uint8_t err = Wire.endTransmission();

if (err == 0) { // no error

err = Wire.requestFrom(adr, (uint8_t)1);

if (err == 1) { // got the value of the byte at address 0

zeroByte = Wire.read();

uint8_t saveByte, testByte;

do {

if (i2cReady(adr)) {

Wire.beginTransmission(adr);

Wire.write(highByte(size));

Wire.write(lowByte(size));

Wire.endTransmission();

err = Wire.requestFrom(adr, (uint8_t)1);

if (err == 1) {

saveByte = Wire.read();

Wire.beginTransmission(adr);

Wire.write(highByte(size));

Wire.write(lowByte(size));

Wire.write((uint8_t)~zeroByte);

err = Wire.endTransmission();

if (err == 0) {

if (!i2cReady(adr)) {

i += sprintf_P(&buf[i], PSTR(" notReady.\n"));

Serial.print(buf);

adr++;

break;

}

Wire.beginTransmission(adr);

Wire.write((uint8_t)0);

err = Wire.endTransmission();

if (err == 0) {

err = Wire.requestFrom(adr, (uint8_t)1);

if (err == 1) {

testByte = Wire.read();

} else {

testByte = ~zeroByte;

}

} else {

testByte = ~zeroByte;

}

} else {

testByte = ~zeroByte;

}

if (!i2cReady(adr)) {

i += sprintf_P(&buf[i], PSTR(" notReady.\n"));

Serial.print(buf);

adr++;

break;

}

Wire.beginTransmission(adr);

Wire.write(highByte(size));

Wire.write(lowByte(size));

Wire.write((uint8_t)saveByte);

Wire.endTransmission();

} else testByte = ~zeroByte;

if (testByte == zeroByte) {

size = size << 1;

}

} while ((testByte == zeroByte) && (size > 0));

if (size == 0) {

i += sprintf_P(&buf[i], PSTR("64k Bytes"));

} else {

i += sprintf_P(&buf[i], PSTR("%dk Bytes"), size / 1024);

}

if (!i2cReady(adr)) {

i += sprintf_P(&buf[i], PSTR(" notReady3.\n"));

Serial.print(buf);

adr++;

continue;

}

Wire.beginTransmission(adr);

Wire.write((uint8_t)0);

Wire.write(zeroByte);

err = Wire.endTransmission();

} else i += sprintf_P(&buf[i], PSTR("Read 0 Failure"));

} else i += sprintf_P(&buf[i], PSTR("Write Adr 0 Failure"));

} else i += sprintf_P(&buf[i], PSTR("Not Present."));

Serial.println(buf);

adr++;

}

bool i2cReady(uint8_t adr) {

uint32_t timeout = millis();

bool ready = false;

while ((millis() - timeout < 100) && (!ready)) {

Wire.beginTransmission(adr);

ready = (Wire.endTransmission() == 0);

}

return ready;

}

void setup() {

Serial.begin(115200);

Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN); //sda - 23, scl - 19

Serial.println("EEPROM size");

eepromSize();

}

void loop() {}

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