Free-to-use user area in flash in ESP-12E

[serkam]

Hi

I need to store some configuration data in the external flash of an ESP-12E ( 4 Mbytes of flash ).

I am understanding that the user area in flash begins at 0x3FE000 ( ESP8266 RTOS SDK Getting Started Guide, page 16 ), where blank.bin is flashed.

But, dumping the first 256 bytes of 0x3FE000, I can see some data in this area. I don't know if it is garbage or valid data from somebody.

So, I want to know which block address is really free to use.

Thanks,

Sergio

[pratik]

No! The last 16kB is for use by the SDK. Writing things there may cause SDK to malfunction.
In non-FOTA mode... The area available for use by user is after irom0.text finishes.
i.e. for 4MB flash, if irom0.text is flashed at 0x10000 and has a length of 0x32000, then your free area is between 0x42000 to 0x3FC000