EEPROM.length() always returns zero if using the default global EEPROM instance

[hideakitai]

Hardware:

Board: ESP32 Dev Module
Core Installation version: 1.0.6, 2.0.0
IDE name: Arduino IDE
Flash Frequency: 80Mhz
PSRAM enabled: No
Upload Speed: 921600
Computer OS: Windows 10

Description:

EEPROM.length() always returns zero if using the default global EEPROM instance. Using my own instance, like the eeprom_class example, I can get the length defined in the constructor (_user_defined_size) not the size defined in begin(size) (_size). Related to #2280.

Sketch: (leave the backquotes for code formatting)

#include "EEPROM.h"

void setup() {
  Serial.begin(115200);
  delay(1000);

  EEPROM.begin(0x100);
  Serial.println(EEPROM.length());  // always zero for global EEPROM instance
}

void loop() {
}

Expected behavior

EEPROM.length() should return the available size of EEPROM even if using the global instance.

Possible improvements

I have created two pull requests. If it looks good for you, please consider merging one of them.

#5774 Add EEPROM::capacity() method to get _user_defined_data and EEPROM::length() returns _size

• capacity() method returns _user_defined_size that is set by the constructor
• length() returns _size that is the true available size of EEPROM

#5775 Remove _user_defined_size and just use _size

I think this is better because _user_defined_size seems to be redundant for me. Just using _size is much clear.

• _user_defined_size is removed because it is redundant in the current code
• length() returns _size that is the true available size of EEPROM