Comments on: ESP32 Flash Memory – Store Permanent Data (Write and Read)

By: Bernie

Bernie — Tue, 12 Aug 2025 22:52:45 +0000

Please correct me if I am wrong. The flash memory is where the code and static data are stored. On the ESP32, the code can be as large as 1063107 bytes, which is what the compiler reports. So why is it that this function only gives us 512 bytes when let’s say 20% of flash memory is unused?

By: Sara Santos

Sara Santos — Thu, 05 Oct 2023 14:06:31 +0000

In reply to Bunty.

Hi.
I think this will help: https://forum.arduino.cc/t/eeprom-storing-numbers-larger-then-256/317188
Regards,
Sara

By: Bunty

Bunty — Thu, 05 Oct 2023 12:07:26 +0000

i want store 1500 string in ESP32 EEPROM each String size is 12 byte its possible

By: Mehdi

Mehdi — Tue, 12 Sep 2023 07:22:58 +0000

Hi
Can use EEPROM and ESP32 like flash memory(micro sd card), and use for example this code:File MyFile = SD.open(dfName, “r”);
thanks

By: Sara Santos

Sara Santos — Mon, 14 Aug 2023 09:10:34 +0000

In reply to Talha Khan.

Hi.
Here’s your answer: https://playground.arduino.cc/Code/EEPROMWriteAnything/
Regards,
Sara

By: Talha Khan

Talha Khan — Fri, 11 Aug 2023 11:40:26 +0000

If I wanted to write a value of more than 255 in a register, what can I do? Is it even possible?

By: Hadrian

Hadrian — Mon, 31 Jul 2023 19:04:22 +0000

Hi Sara, I’ve been serching for tutorials on how to use external SPI flash memory chips, but have only found some about EEPROM. I would like, if it is possible, to use a flash memory chip as if it was an SD card to write and read strings. I really don’t know if there are any libraries that that allow to do this. I have previously used the internal memory on the ESP32 with the SPIFFS file system, but as far as I understand that it’s not the same as hooking up an external SPI flash memory module. My objective is to store G-code. Perhaps it could be more complicated than I think it is since there’s less information available about this topic.

By: Maxim Kachurovskiy

Maxim Kachurovskiy — Sun, 07 May 2023 12:04:00 +0000

Beware EEPROM.commit() – it takes 30ms and during that time interrupts aren’t handled. They get processed once commit is done.

All except the first interrupt that happen during those 30ms are ignored.

https://github.com/espressif/arduino-esp32/issues/8169

By: Fritz

Fritz — Wed, 19 Oct 2022 11:04:38 +0000

In reply to Imre.

I know there’s an Arduino library called EEPROMex.h which permits managing of floats in EEPROM.
I don’t know if this library Is compatibile in ESP32…

By: Sara Santos

Sara Santos — Sun, 31 Oct 2021 12:34:49 +0000

In reply to Tamarni Harris.

Hi.
It already does that automatically.
Regards,
Sara