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

janderkan

Well-Known Member

Licensed User

Longtime User

• Mar 13, 2021

• #2

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

 

Upvote 0

amorosik

Expert

Licensed User

• Mar 13, 2021

• #3

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?

 

Upvote 0

janderkan

Well-Known Member

Licensed User

Longtime User

• Mar 13, 2021

• #4

Have you tried ?

 

Upvote 0

Cableguy

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #5

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

 

Last edited: Mar 13, 2021

Upvote 0

Daestrum

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #6

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

 

Upvote 0

Cableguy

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #7

From the Link above we can read

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

Click to expand...

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)

 

Upvote 0

Daestrum

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #8

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

 

Upvote 0

Cableguy

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #9

Daestrum said:

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

Click to expand...

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

 

Last edited: Mar 13, 2021

Upvote 0

Cableguy

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #10

See this:
ESP32 - Wikipedia

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

 

Upvote 0

Daestrum

Expert

Licensed User

Longtime User

• Mar 13, 2021

• #11

Probably uses some flash as it has 4MB.

 

Upvote 0

thetahsk

Active Member

Licensed User

Longtime User

• Mar 13, 2021

• #12

amorosik said:

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

Click to expand...

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

 

Upvote 0