ESP8266 Community Forum

- Tue Sep 09, 2014 2:30 pm #383

I don't own one yet, I will inform you about that.

Does anyone know a way to modify internal eeprom of the chip?

I have seen the following which looks like a NV data storage, but no guarantee.

Code: Select allsave_user_param(PRIV_PARAM_SAVE_SEC, &plug_param, sizeof(struct plug_saved_param));

Maybe the Mac is stored that alike?
Think it's worth to explore this feature since a module could autonomously recover from a power down situation.

But we don't know so many things about this module. Eg how is the transmitter power configured? Etc...

- Tue Sep 09, 2014 3:05 pm #384 There is a "read_mac_addr_from_otp" symbol at the very beginning of libmain.a, so there is a good chance that the MAC address is stored into OTP ROM and cannot be modified.

As for the save_user_param() function, this is likely a function that uses some SPI Flash sectors to store user data like connection information.

From jonsmirl's post, this looks like the last 16 KB at the end of the first half of 512KB Flash, so 240KB~256KB + Flash start address. As these SPI Flash chips usually have 4KB sectors, this is 4 sector long, so hopefully there is some redundancy to avoid loosing information in case of a power failure just while you are writing to Flash...

- Thu Sep 11, 2014 11:42 pm #468 Just checked. Each of mine have a unique MAC address, I have the old electrodragon ones, without the firmware updaty pins. New ones with those pins are coming in the mail soon.

- Thu Sep 18, 2014 3:17 am #718 This is great, thanks.