Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Mon, 23 Jun 2025 08:48:38 GMT

Hi Khalil,

That's great news. I will close this case then 🙂

Best regards,

Hieu

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Khalil Tawosli — Mon, 23 Jun 2025 00:28:29 GMT

Hi Hieu,

I can confirm that the LittlefFS mount on the external SPI flash is successfully completed and now is functionning as expecetd.

Thank you verry much for you support and guidance throughout the process.

Best Regards,

Khalil

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Fri, 20 Jun 2025 14:42:53 GMT

Hi Khalil,

It seems adding CONFIG_PM_OVERRIDE_EXTERNAL_DRIVER_CHECK=y will fix it.

Ref: Little FS on external FLASH with nrf9161dk and NCS 2.8.0

Regards,

Hieu

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Khalil Tawosli — Tue, 17 Jun 2025 04:25:10 GMT

Hi Hieu,

I've attached all relevant project files in a zip file format. The project is based on the original littlefs filesystem sample project.

Cheers,

Khalil

devzone.nordicsemi.com/.../0383.littlefs.zip

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Mon, 16 Jun 2025 13:47:00 GMT

Hi Khalil,

Could you please share your current generated partitions.yml, and all code lines relevant to mounting the FS?

Best regards,

Hieu

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Khalil Tawosli — Mon, 16 Jun 2025 03:08:10 GMT

Hi Hieu,

Thank you again for looking into my issue and for your latest suggestion — it successfully resolved the build warning.

However, I’m still encountering the same runtime error -ENODEV (-19) when attempting to mount the LittleFS partition.

Here’s the full terminal output:

Following is the terminal printout string:
I: littlefs partition at /lfs1
I: LittleFS version 2.9, disk version 2.1
E: can't open flash area 1
E: fs mount error (-19)
E: Automount /lfs1 failed: -19
*** Booting nRF Connect SDK v3.0.1-9eb5615da66b ***
*** Using Zephyr OS v4.0.99-77f865b8f8d0 ***
Sample program to r/w files on littlefs
E: FAIL: unable to find flash area 1: -2

I'm using the nRF54L15DK development board, and when I read the external flash JEDEC ID, it returns [c2 28 17], which correctly identifies the MX25R64 chip — confirming that there is no hardware connectivity issue.

Please let me know what else I should check or modify to get past this runtime mount error.

Best regards,
Khalil

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Fri, 13 Jun 2025 18:09:38 GMT

Hello Khalil,

My apology. It seems there was some syntax change. and the affiliation line should no longer be written the way I sent you. Could you please replace

  affiliation:
    -disk

with

  affiliation: disk

Please make that replacement and retry from the pm_static.yml step.

[quote user="Khalil Tawosli"]P.S.: I removed /delete-node/ &storage_partition; line from app.overlay and tried again. but still filesystem failes to mount[/quote]

As you are using the Partition Manager, the partitioning in the DeviceTree isn't in effect. Ref: Partition Manager.

Best regards,

Hieu

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Khalil Tawosli — Wed, 11 Jun 2025 04:32:52 GMT

Hi Hieu,

Thank you for the clarification.

I’ve carefully gone through your recommended five steps again. Below is a detailed breakdown of what I did:

I removed the pm_static.yml file from the project, along with the previously added app.conf and app.overlay files, otherwise the project wouldn't buld/compile. The project is now the original LittleFS Sample project.
I did a pristine build. No build errors observed
I programmed the NRF54L15DK board. I could see from the consol output the internal flash is mounted correctly and the filesystem operated as expected..
I copied the partitions.yml from the build directory as a new pm_static.yml into the project directory.

In pm_static.yml file, I reconfigured the littlefs partition to external flash.

app:
  address: 0x0
  end_address: 0x15f000
  region: flash_primary
  size: 0x15f000
bootconf:
  address: 0xffd080
  end_address: 0xffd084
  region: bootconf
  size: 0x4
littlefs_storage:
  address: 0x00000000
  end_address: 0x00400000
  region: external_flash
  device: mx25r6435f
  size: 0x400000
  affiliation:
    -disk
  extra_params: {
      disk_name: "littlefs",
      disk_cache_size: 4096,
      disk_sector_size: 512,
      disk_read_only: 0
    }
otp:
  address: 0xffd500
  end_address: 0xffd9fc
  region: otp
  size: 0x4fc
sram_primary:
  address: 0x20000000
  end_address: 0x2002f000
  region: sram_primary
  size: 0x2f000

The project fail to compile at this point, so I added back the app.conf and app.ovrelay files back into the project. It now compiles with the following warning :

   warning: ISO C99 requires whitespace after the macro name
   58 | #define PM_FOREACH_AFFILIATED_TO_-disk(fn)  fn(LITTLEFS_STORAGE)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~

After flashing the console output is as follows:

I: littlefs partition at /lfs1
I: LittleFS version 2.9, disk version 2.1
E: can't open flash area 1
E: fs mount error (-19)
E: Automount /lfs1 failed: -19
*** Booting nRF Connect SDK v3.0.1-9eb5615da66b ***
*** Using Zephyr OS v4.0.99-77f865b8f8d0 ***

For your reference, here's the content of the relevant files:

app.conf:

CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL=y

app.overlay:

/delete-node/ &storage_partition;

/ {
    chosen {
        nordic,pm-ext-flash = &mx25r64;
    };
};

/ {
	fstab {
		compatible = "zephyr,fstab";
		lfs1: lfs1 {
			compatible = "zephyr,fstab,littlefs";
			mount-point = "/lfs1";
			partition = <&lfs1_partition>;
			automount;
			read-size = <16>;
			prog-size = <16>;
			cache-size = <64>;
			lookahead-size = <32>;
			block-cycles = <512>;
		};
	};
};

&mx25r64 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		lfs1_partition: partition@0 {
			label = "lfs1_partition";
			reg = <0x00000000 0x00800000>;
		};
	};
};

Could you please advise which step or file configuration might be incorrect or incomplete?

I'd apprecate your help in resolving this issue.

Best Regards,

Khalil

P.S.: I removed /delete-node/ &storage_partition; line from app.overlay and tried again. but still filesystem failes to mount.

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Tue, 10 Jun 2025 18:59:21 GMT

Hello Khalil,

That was not all the steps I recommended. Could you follow them closely please?

Best regards,

Hieu

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Khalil Tawosli — Fri, 06 Jun 2025 01:29:22 GMT

Thank you, Hieu, for your prompt response.

I tried implementing your suggestion, but unfortunately, the modified LittleFS sample still throws the following runtime error:

Sample program to r/w files on littlefs
E: FAIL: unable to find flash area 1: -2

I: littlefs partition at /lfs1
I: LittleFS version 2.9, disk version 2.1
E: can't open flash area 1
E: fs mount error (-19)
E: Automount /lfs1 failed: -19

Below is the compiled partitions.yaml output after applying your changes:

app:
address: 0x0
end_address: 0x165000
region: flash_primary
size: 0x165000
bootconf:
address: 0xffd080
end_address: 0xffd084
region: bootconf
size: 0x4
external_flash:
address: 0x6000
end_address: 0x800000
region: external_flash
size: 0x7fa000
littlefs_storage:
address: 0x0
device: DT_CHOSEN(nordic_pm_ext_flash)
end_address: 0x6000
placement:
before:
- tfm_storage
- end
region: external_flash
size: 0x6000
otp:
address: 0xffd500
end_address: 0xffd9fc
region: otp
size: 0x4fc
sram_primary:
address: 0x20000000
end_address: 0x2002f000
region: sram_primary
size: 0x2f000

And here's the pm_static.yaml content I'm using:

littlefs_storage:
address: 0xe7600
end_address: 0x800000
region: external_flash
device: mx25r6435f
size: 0x718000
affiliation:
-disk
extra_params: {
disk_name: "littlefs",
disk_cache_size: 4096,
disk_sector_size: 512,
disk_read_only: 0
}

It’s worth noting that the generated partitions.yaml looks exactly the same even when I used a simplified pm_static.yaml like this:

littlefs_ext_storage:
address: 0x00000000
size: 0x00800000
region: external_flash
placement:
before: end

I’m still stuck and wondering if you or anyone else could share a working sample project targeting the nRF54L15-DK that successfully mounts LittleFS on external SPI flash. That would be incredibly helpful for learning and troubleshooting.

Thanks again for your support!

Best regards,
Khalil

RE: Unable to Mount LittleFS File System On External Flash On NRF54L15-DK

Hieu — Thu, 05 Jun 2025 08:14:08 GMT

Hello Khalil,

Could you please follow these steps:

Remove your pm_static.yml from the project
Build pristine once
Verify that features in this build work. Stop here if this step failed.
Copy the partitions.yml from that build directory as a new pm_static.yml
Reconfigure the littlefs partition to external flash, remember to add some properties under the partitions as followed:
affiliation:
-disk
extra_params: {
disk_name: "littlefs",
disk_cache_size: 4096,
disk_sector_size: 512,
disk_read_only: 0
}

Here is an example:
littlefs_storage:
address: 0xe7600
end_address: 0x800000
region: external_flash
device: mx25r6435f
size: 0x718000
affiliation:
-disk
extra_params: {
disk_name: "littlefs",
disk_cache_size: 4096,
disk_sector_size: 512,
disk_read_only: 0
}

Hieu