ESP-WROOM-02D-N2 16Mbit(512KB+512KB) or 16Mbit(1024KB+1024KB)?

[pieterc]

Hi there!

I programmed the module with ESP8266_NonOS_AT_Bin_V1.7.4 FW. I used the following esptool.py command:

esptool --port COM27 write-flash -fm qio -fs 2MB-c1 \
0x000000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\boot_v1.7.bin \
0x001000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\at\1024+1024\user1.2048.new.5.bin \
0x101000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\at\1024+1024\user2.2048.new.5.bin \
0x1FB000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\blank.bin \
0x1FC000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\esp_init_data_default_v08.bin \
0x1FE000 ESP8266_NonOS_AT_Bin_V1.7.4\bin\blank.bin

The bootloader reported the following:
2nd boot version : 1.7(5d6f877)
SPI Speed : 40MHz
SPI Mode : QIO
SPI Flash Size & Map: 16Mbit(512KB+512KB)

I discovered that I had to use "-fs 2MB-c1" and then the SPI Flash Size & Map was correctly reported as 16MBit(1024KB+1024KB).

Why is "2MB-c1" the correct option? Is there a document that I can read that explains this?

The old version of the flash_download_tool.exe allowed a FLASH SIZE choice, e.g. "16MBit" or "16MBit-C1" but the latest version that I tried did not. I suspect that it detects the flash size as 2MB and then uses the wrong SPI Flash Map. Can you confirm this?

Is the SPI Flash Mode stored at address 0x000002 and the SPI Flash size and frequency stored at address 0x000003?

Thanks in advance,
Pieter