I'd like to flash the eeprom sector with content so that the eeprom already holds data when it boots the first time. How do I upload such an eeprom file like I would do with avrdude on an atmega? Is there a tool that can be installed in the arduino IDE like the data uploader?

  • esptool can download and upload any region of the esp flash
    – Juraj
    Nov 3, 2019 at 14:35
  • @Juraj I can't find any dedicated command line option. Like, for my atmega I would use something like -U eeprom:w.... Do I have to find the address offest myself and if so, where? Actually, where do I find the actual partition table the arduino IDE uses?
    – Sim Son
    Nov 3, 2019 at 14:53
  • I said "flash". the esptool command is read_flash and write_flash. I don't write an answer, because I never tested that.
    – Juraj
    Nov 3, 2019 at 18:47

1 Answer 1


The ESP8266 has no EEPROM.

Instead the flash memory is partitioned into different areas for different purposes. One of those areas is set aside for "EEPROM Emulation" data.

To upload to that area you first need to know where that area is in the flash memory, and that is dependent on what partitioning scheme you are using at the moment.

Once you have worked that out (look in the partition scheme files in the core for more information) you can then use esptool to upload data to the right area of flash.

  • @Juraj I did, yes, but technically I am also correct saying it has no flash, since it relies on an external flash chip :)
    – Majenko
    Nov 3, 2019 at 18:46

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