LittleFS and Arduino UNO R4 WiFi

Community General Discussion
1

I’ve found conflicting information regarding UNO R4 WiFi compatibility with the LittleFS (or prefixed with 107) library. I’ve found several examples but none will compile. Wondering if there is an error in showing this compatibility. Perhaps something to do with how memory is configured on this board.

2

From what I see, LittleFS is designed to work with those micros that have "extensive" and "internal" flash memory, like the ESP32 or RP2040 (2MB to 16MB, typical, implemented in a QSPI flash chip.) The Renesas chip doesn't have that sort of memory, and the ESP32 WiFi module, while it MIGHT, isn't normally programmed via Arduino (it just runs WiFi software.)

(Hmm. In theory, the ESP32 module has 8MB of flash (if you believe the R4 Uno spec sheet), which seems like a lot for the functions it provides. But I don't see anything that allows you to use that as storage from the Renesas CPU.)

3

You can verify this from table 1-1 in the datasheet for the ESP32-S3-MINI-1-N8 module used on the board:

https://www.espressif.com/en/products/modules#:~:text=WROOM-2.glb-,ESP32-S3-MINI-1,-ESP32-S3-MINI

Ordering Code Flash PSRAM1 Ambient Temp. (°C) Size (mm)
ESP32-S3-MINI-1-N8 8 MB (Quad SPI) - –40 ∼ 85 15.4 × 20.5 × 2.4
4

Seems like I might be right that not really compatible without much jiggering.

5

I agree. It is possible to program the ESP32-S3 "bridge" module on the board, just as you would do with a normal ESP32-based board:

https://docs.arduino.cc/tutorials/uno-r4-wifi/cheat-sheet/#programming-the-esp32-advanced

However, this is a very advanced usage of the board and could result in the board being in a state where it can no longer be used normally. Arduino provides a special firmware that normally runs on the board's "bridge" module, and when a custom sketch is uploaded to the ESP32-S3 that standard firmware is replaced. Likewise, the filesystem of the "bridge" module's flash memory is used to store the network authentication credentials when the board is used as an Arduino Cloud IoT Device. So replacing the firmware or filesystem on the module can result in unexpected impacts on the usability of the board as an UNO R4 WiFi.

Please provide a detailed description of what you are attempting to accomplish. The forum helpers may be able to suggest solutions that don't rely on the use of a littlefs filesystem.