Comments on: ESP32 Save Data Permanently using Preferences Library

By: Stefano

Stefano — Wed, 12 Mar 2025 08:40:41 +0000

Great tutorial: really easier and faster than SPIFF that I used in past… many thanks!!

By: Sara Santos

Sara Santos — Fri, 06 Dec 2024 10:28:03 +0000

In reply to Uwe.

Hi.
Thanks for noticing.
It’s fixed now.
Regards,
Sara

By: Uwe

Uwe — Wed, 04 Dec 2024 20:38:40 +0000

Hi,
thanks for this very useful help.
There is a small typo:
gettULong64 instead of getULong64 in the “Get a Key Value (Read Value)” section.
Br
Uwe

By: Patrick

Patrick — Tue, 15 Oct 2024 08:12:15 +0000

I would like to ask how much read/write cycle is ESP is capable of?

Because i am planning to make a product counter with ESP

daily count: 1800 pcs

trigger :1 million pcs

My concer is how to ensure the data is preserved

Thanks

By: Xylopyrographer

Xylopyrographer — Fri, 24 May 2024 05:35:30 +0000

In reply to Allen Mulvey.

Preferences uses a portion of the on-board flash as its namespace. Thus when the flash is erased, so is the space used by the Preferences library. This is how it has always been.

For more detail, see the Resources section at the end of the Preferences Tutorial on the arduino-esp32 GitHub site at: https://docs.espressif.com/projects/arduino-esp32/en/latest/tutorials/preferences.html

By: Allen Mulvey

Allen Mulvey — Mon, 20 May 2024 23:49:21 +0000

This article is a little old and these things change fast. Using the Arduino IDE and setting “Erase all flash before sketch upload” to enabled now (May 2024) deletes the preferences.

Thanks again for all your work.

By: jorge medina

jorge medina — Mon, 29 Jan 2024 10:29:27 +0000

Antes que nada gracias por todos sus aportes, siempre son el impulso suficiente para desarrollar proyectos con cada nueva tecnología que ocupo, asi que de nuevo muchas gracias!! Hoy recurro a ustedes para obtener ayuda respecto a la compilación de la biblioteca en VisualStudioCode, ya que no encuentro solución en ningún sitio. El problema es que al compilar aparece el error “For ESP32 devices, please use the native Preferences library”. Este error se presenta con la versión de biblioteca 2.1.0 y 2.0.0, las dos únicas versiones de esta. Tambien probé cambiar la version de framework, desde la 6.5 hasta la 4.4, y da el error con todas las combinaciones entre versiones de framework y biblioteca.

By: Bravo J.

Bravo J. — Sat, 27 Jan 2024 07:42:05 +0000

Very nice tutorial.
I have one question: Do the stored data survive an OTA update where both the program and files stored in littleFS are updated?

By: Ilija Iliev

Ilija Iliev — Sat, 25 Nov 2023 15:13:00 +0000

In reply to Mal Oldis. Hello Mal Oldis, When you use Arduino IDE, there is configuration options for the device. By default 4MB are splitted in 2 parts: for NVM and for code flash. Usually 1.5 MB is NVM emulation but you can extend or remove it depend on your needs. Also can burn bootloader, add OTA, etc.

By: Mal Oldis

Mal Oldis — Fri, 24 Nov 2023 22:44:25 +0000

Hi Sara and Roi. I have been using preferences extensively but am a bit concerned about it’s limits. How do I determine what the memory limits are? Also in your preferences guide, you mention the use of preferences.end();. I am not sure when to use it.
Thanks so much.