Doubts about Internal Flash, External Flash and PSRAM in Arduino Nano ESP32

Official Hardware Nano Family Nano ESP32
1

I have an Arduino Nano ESP32 board.

Arduino mentions the following here:

Nano ESP32 packs Wi-Fi®/Bluetooth® connectivity, 8 MB of internal and 16 MB of external flash memory, 512 kB RAM.

and the following here:

384 kB ROM
512 kB SRAM
16 MB of Flash (external, provided via GD25B128EWIGR)
8 MB of PSRAM

I am beginner and don't have much idea about how RAM, ROM, PSRAM, Flash work and what are their uses.

I have few doubts:

  1. Is internal flash of no use (built-in but never used) since everything is managed by external flash? If yes, why Arduino mentioned it on box and documentation?
  2. If there is any role of internal flash, what is that? Did the documentation use PSRAM instead of Internal Flash by mistake or PSRAM is completely different?

Thanks in advance.

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It uses the NORA-W106-10B module which has the esp32 along with 8MB of flash and 8MB of PSRAM. The board also has 16MB of external flash. In the documentation I don't see anything about the use of the 8MB of internal flash, so I assume it is ignored and only the external flash is used.

PSRAM is PseudoStatic RAM. It is dram (dynamic ram) that has onboard refresh so that is can be used like sram (static ram). It has higher density than sram and is easier to use than dram. On the Arduino esp32 it can be used as additional ram with some restrictions and lower performance compared to internal ram.

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Thanks @kumardeo for pointing out this! The store page indeed contains confusing details - I have submitted a request for it to be fixed ASAP.

The information in the Datasheet and Cheat Sheet is correct:

  • there is no "internal flash", neither in the CPU or the NORA module;
  • there's a 512kB RAM inside the ESP32-S3 CPU;
  • the 8MB PSRAM is soldered over the CPU inside the NORA-W106 module;
  • the 16MB Flash is an external chip mounted on the board.
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Thanks :slight_smile: