Non-volatile memory on ESP32-PICO-V3

[alessandro]

Hello,

we are using the ESP32-PICO-V3 in our custom PCB and we would like to expand the amount of non-volatile memory available.

One option we are considering is to add an SD card.
In that case, is it possible to use for the SD card the same pins used for the internal flash?

Another option would be to use an external SPI flash memory.
I have two questions here:
1) again, can we use the same pins used for the internal flash?
2) what's the biggest flash size we can add?

Keep in mind that we don't want to extend the code space, we can use the internal 4MB flash for that. The external flash (or SD card) would be used only as non-volatile storage.

Thanks

[becorey]

Datasheet says:

Pins CMD/IO11 and CLK/IO6 are used for connecting the embedded flash, and are not recommended for other
uses. For details, please see Section 5 Schematics.

You should probably use SPI on other GPIO pins for your sd card.

Spi flash vs sd card has typical tradeoffs, size of your device, number of writes before flash wears out, sd card is replaceable, etc.

[alessandro]

Thanks!
In the end, we will probably not go for an SD card due to space constraints. So we are now looking at SPI flash chips.
It seems that NOR flash is well supported in the IDF, also in terms of having a filesystem on it (i.e. SPIFFS), while NAND flash seems not to be supported at all. Correct me if I'm wrong.

Regarding NOR flash, there should be no limit on the size supported, right?
We are thinking of using an external 2Gbit NOR flash on different GPIOs from the ones used for the internal one.