B4R Question Heltec Wifi Kit 32 - how to store permanent value ?

[amorosik]

Is it possible, from code, to permanently store information on cards of this type, Heltec wifi kit 32?
For example calibration values, or similar, that must remain stored even in the absence of board power

 

[janderkan]

https://www.b4x.com/android/forum/threads/writing-and-reading-from-the-eeprom.65711/

 

[amorosik]

I don't think there is an eeprom in the Heltec Wifi kit 32 card
There is main flash memory that is written with the program loaded via usb
And in that area I would like to know if it is possible to write / read from program code
Or maybe you meant to tell me that it is possible to use the functions provided for eeprom memory also on the flash memory of the card?

 

[janderkan]

Have you tried ?

 

[Cableguy]

Almost every ESP xxxxx based boards take the expressif board as piggyback. The Expressif boards all have expressif (although it's only a few kilobytes if I'm not mistaken)

Take a good look at the chip side of your board... you should see 3 of them.
The big one is the ESP chip in smd form, another small chip, smaller in size, is your USB controller, and there should be a third, sized between the other 2, 8pin dip chip. That's the eeprom.

In the above photo:
Left most is the ESP, middle is eeprom, right is the USB controller

 

[Daestrum]

The Heltec info says the eeprom use is deprecated and you use Preferences instead. Not tried it tho.
Preferences

 

[Cableguy]

From the Link above we can read

The Preferences library is a wrapper around the Non-volatile storage on ESP32 processor.

And Wikipédia says that a "Non-Volatile Memory" is...
Non-volatile memory - Wikipedia

This brings us back to..... EEPROM ( Electrically Erasable Programmable Read Only Memory)

 

[Daestrum]

It was the 495KB write limit that made me think it wasn't eeprom as that's a lot of storage.

 

[Cableguy]

It was the 495k write limit that made me think it wasn't eeprom as that's a lot of storage.

ESP8266 uses an external EEPROM, maybe the ESP32 uses an "Internal" reserved space that act as one

 

[Cableguy]

See this:
ESP32 - Wikipedia

As you can see, it does have an internal storage of 520Kb

 

[Daestrum]

Probably uses some flash as it has 4MB.

 

[thetahsk]

Is it possible, from code, to permanently store information on cards of this type, Heltec wifi kit 32?
For example calibration values, or similar, that must remain stored even in the absence of board power

Everything is explained here, use the SPIFFS Filesystem for storage.

rESP8266FileSystem (SPIFFS)

ESP8266 comes with built-in file system provisioned on the chip flash. The file system is useful for storing persistent information. The size available varies but on most devices it is more than 1mb. See the table here: https://github.com/esp8266/Arduino/blob/master/doc/filesystem.rst...

www.b4x.com