Unable to use LittleFS on External Flash on nrf9160

RE: Unable to use LittleFS on External Flash on nrf9160

Ben_R831 — Wed, 28 Jun 2023 15:58:01 GMT

Hello Vidar,

Awesome. That makes sense. Tried the static partition file, and it worked nicely. I also realized I read the datasheet wrong and that the external flash chip has 64Mbit (8MB) verses 64MByte.

Thank you for your help,

Ben

RE: Unable to use LittleFS on External Flash on nrf9160

Vidar Berg — Wed, 28 Jun 2023 08:51:53 GMT

Hello Ben,

The external flash region gets added when you have set the 'pm-ext-flash' property, as explained in the External Flash of the partition manager documentation. However, it does not automatically place the littlefs partition within it. We added the CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL symbol in v2.1.0 to allow the partition to be added automatically.

For v1.7.1, you need to define the partition yourself. You can do this by creating a file named 'pm_static.yml' that contains the following:

littlefs_storage:
  region: external_flash
  address: 0x0
  size: 0x10000
external_flash:
  address: 0x10000
  size: 0x7F0000
  device: MX25R64
  region: external_flash

Then place the file in your project directory so it gets picked up by the build system (Static Configuration).

Tip: you can use the "Memory report" button in VS code if you want to view the memory layout, or "$ west build -t partition_manager_report" if you are building from the command line.

Best regards,

Vidar

RE: Unable to use LittleFS on External Flash on nrf9160

Ben_R831 — Tue, 27 Jun 2023 23:43:35 GMT

One interesting observation is that automount or mounting in main does use the external flash. However, mounting via shell via the "fs mount" command uses the internal flash.

RE: Unable to use LittleFS on External Flash on nrf9160

Ben_R831 — Tue, 27 Jun 2023 23:36:47 GMT

Hello Vidar,

Thank you for the response. I tried your device overlay. At first it didn't work as expected. However, I noticed that it did not define the pins and it marked the mx25r64 as disabled. I made slight modifications and I got it to work.

Here is the overlay:

/*
 * Copyright (c) 2019 Peter Bigot Consulting, LLC
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 /delete-node/ &storage_partition;

 /* Configure partition manager to use mx25r64 as the external flash device */
 / {
	 chosen {
		 nordic,pm-ext-flash = &mx25r64;
	 };
 };

 &spi3 {
	status = "okay";
	sck-pin = <13>;
	mosi-pin = <11>;
	miso-pin = <12>;
	 cs-gpios = <&arduino_header 16 GPIO_ACTIVE_LOW>, /* D10 */
			<&gpio0 25 GPIO_ACTIVE_LOW>;
	 mx25r64: mx25r6435f@1 {
		 compatible = "jedec,spi-nor";
		 status = "okay";
		 reg = <1>;
		 spi-max-frequency = <8000000>;
		 label = "MX25R64";
		 jedec-id = [c2 28 17];
		 sfdp-bfp = [
			 e5 20 f1 ff  ff ff ff 03  44 eb 08 6b  08 3b 04 bb
			 ee ff ff ff  ff ff 00 ff  ff ff 00 ff  0c 20 0f 52
			 10 d8 00 ff  23 72 f5 00  82 ed 04 cc  44 83 68 44
			 30 b0 30 b0  f7 c4 d5 5c  00 be 29 ff  f0 d0 ff ff
		 ];
		 size = <67108864>;
		 has-dpd;
		 t-enter-dpd = <10000>;
		 t-exit-dpd = <35000>;
	 };
 };
 
 
 / {
	 fstab {
		 compatible = "zephyr,fstab";
		 lfs1: lfs1 {
			 compatible = "zephyr,fstab,littlefs";
			 mount-point = "/lfs1";
			 partition = <&lfs1_part>;
			 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_part: partition@0 {
			 label = "storage";
			 reg = <0x00000000 0x00010000>;
		 };
	 };
 };

prj.conf (changed slightly... added PM_EXTERNAL_FLASH)

# Optionally force the file system to be recreated
#CONFIG_APP_WIPE_STORAGE=y

# fs_dirent structures are big.
CONFIG_MAIN_STACK_SIZE=2048

# Let __ASSERT do its job
CONFIG_DEBUG=y

CONFIG_LOG=y

CONFIG_FLASH=y
CONFIG_FLASH_MAP=y
CONFIG_FLASH_PAGE_LAYOUT=y

CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=y

# CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL=y


CONFIG_FLASH=y
CONFIG_LOG=y
#CONFIG_FS_LOG_LEVEL_DBG=y
CONFIG_HEAP_MEM_POOL_SIZE=16384
CONFIG_SHELL=y
CONFIG_SHELL_LOG_LEVEL_INF=y
CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_SHELL=y
CONFIG_FILE_SYSTEM_LITTLEFS=y
CONFIG_FLASH_MAP=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

CONFIG_PM_EXTERNAL_FLASH=y
CONFIG_PM_EXTERNAL_FLASH_DEV_NAME="MX25R64"

And this worked for the "_ns" build target which is perfect.

For the logs, does this verify it is using the external flash? (I do notice the MX25R64 indicated, and the size is about 8MB, so it seems correct.) Is there a way to increase the size (as the chip has 64MB)?

*** Booting Zephyr OS build v2.6.99-ncs1  ***
Area 0 at 0x0 on MX25R64 for 8388608 bytes
/lfs1 automounted
/lfs1: bsize = 16 ; frsize = 4096 ; blocks = 2048 ; bfree = 2046
/lfs1/boot_count stat: 0
        fn 'boot_count' siz 4
/lfs1/boot_count read count 4: 4
/lfs1/boot_count seek start: 0
/lfs1/boot_count write new boot count 5: 4
/lfs1/boot_count close: 0
/lfs1 opendir: 0
  F 4 boot_count
End of files
/lfs1 unmount: 0
[00:00:00.203,002] <inf> littlefs: littlefs partition at /lfs1
[00:00:00.203,063] <inf> littlefs: LittleFS version 2.2, disk version 2.0
[00:00:00.204,986] <inf> littlefs: FS at MX25R64:0x0 is 2048 0x1000-byte blocks with 512 cycle
[00:00:00.204,986] <inf> littlefs: sizes: rd 16 ; pr 16 ; ca 64 ; la 32
[00:00:00.208,312] <inf> littlefs: /lfs1 mounted
[00:00:00.208,312] <inf> littlefs: Automount /lfs1 succeeded
[00:00:00.256,896] <inf> littlefs: /lfs1 unmounted

Thanks,

Ben

RE: Unable to use LittleFS on External Flash on nrf9160

Vidar Berg — Tue, 27 Jun 2023 12:32:46 GMT

Hello Ben,

I tried to do the same with the littlefs sample using the following device tree overlay:

/*
 * Copyright (c) 2019 Peter Bigot Consulting, LLC
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/delete-node/ &storage_partition;

/* Configure partition manager to use mx25r64 as the external flash device */
/ {
    chosen {
        nordic,pm-ext-flash = &mx25r64;
    };
};

&spi3 {
	cs-gpios = <&arduino_header 16 GPIO_ACTIVE_LOW>, /* D10 */
		   <&gpio0 25 GPIO_ACTIVE_LOW>;
	mx25r64: mx25r6435f@1 {
		compatible = "jedec,spi-nor";
		status = "disabled";
		reg = <1>;
		spi-max-frequency = <8000000>;
		label = "MX25R64";
		jedec-id = [c2 28 17];
		sfdp-bfp = [
			e5 20 f1 ff  ff ff ff 03  44 eb 08 6b  08 3b 04 bb
			ee ff ff ff  ff ff 00 ff  ff ff 00 ff  0c 20 0f 52
			10 d8 00 ff  23 72 f5 00  82 ed 04 cc  44 83 68 44
			30 b0 30 b0  f7 c4 d5 5c  00 be 29 ff  f0 d0 ff ff
		];
		size = <67108864>;
		has-dpd;
		t-enter-dpd = <10000>;
		t-exit-dpd = <35000>;
	};
};


/ {
	fstab {
		compatible = "zephyr,fstab";
		lfs1: lfs1 {
			compatible = "zephyr,fstab,littlefs";
			mount-point = "/lfs1";
			partition = <&lfs1_part>;
			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_part: partition@0 {
			label = "storage";
			reg = <0x00000000 0x00010000>;
		};
	};
};

But I realized the CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL symbol didn't get introduced until SDK v2.1.0: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/releases/release-notes-2.1.0.html#scripts.

Would it be an option to upgrade to a more recent version? If not, I think the solution will be to create a static partition file with your partition in external flash (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/scripts/partition_manager/partition_manager.html#configuring-static-partitions) or cherry-pick the changes from SDK 2.1.0.

Another post with a similar question: Using LittleFS with mx25r64 and nRF Connect VS Code

Also, for reference, here are instructions on how to add external flash from the latest SDK documentation:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/working_with_nrf/nrf91/nrf9160.html#adding-the-configuration-and-devicetree-option

Best regards,

Vidar

EDIT: I see now that the overlay for the spi3 node should be redundant if you build for revision 0.14.0 of the board (default): https://github.com/nrfconnect/sdk-zephyr/blob/main/boards/arm/nrf9160dk_nrf9160/nrf9160dk_nrf9160_common_0_14_0.dtsi#L40. Prior versions did not include the flash IC so it was not defined in the device tree either.