Example of using external flash that is on nRF5340dk ?

[IvanR]

Im having trouble setting up and using flash on nRF5340dk. 

Is there any example on how to use LittleFS on external flash that is on the dev kit?

[Amanda Hsieh]

Hi, 

Here is the example https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/subsys/fs/littlefs.  

Please duplicate this https://github.com/nrfconnect/sdk-zephyr/blob/main/samples/subsys/fs/littlefs/boards/nrf52840dk_nrf52840_qspi.conf  config file and rename it to nrf5340dk_nrf5340_cpuapp.conf.

Duplicate https://github.com/nrfconnect/sdk-zephyr/blob/main/samples/subsys/fs/littlefs/boards/nrf52840dk_nrf52840_qspi.overlay overlay file, rename it to nrf5340dk_nrf5340_cpuapp.overlay and update with the following content:

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

/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_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>;
		};
	};
};

Then, you could get the output like this

Regards,
Amanda H.

[IvanR]

Thank you, It's working. I can now see all 8mb of flash. But there is an issue. 

When running the littlefs example I get 

Area 0 at 0x0 on mx25r6435f@0 for 8388608 bytes - Which is correct

but when I transfer that code, exact code, to my app I get 

Area 2 at 0xfa000 on flash-controller@39000 for 24576 bytes

Ive been going over whats different but cant find it, Maybe Im missing something?

I also tried moving my code to littlefs example and everything was going fine until I added

CONFIG_SYS_HEAP_RUNTIME_STATS=y to prj.conf. 

It switched to flash  flash-controller@39000, after commenting it out it stayed with flash and I cant get it to go back to mx25??

[IvanR]

Ok, an Update. As soon as I add 

CONFIG_BT=y to nrf5340dk_nrf5340_cpuapp.conf

the example stops working.

Been testing for hours now removing and adding line by line and as soon BT is enabled the example falls apart.

[Amanda Hsieh]

Hi, 

Have a look at this post. 

-Amanda H.

[IvanR]

nrf5340dk_nrf5340_cpuapp.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_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 0x00800000>;
		};
	};
};

added CONFIG_PM_PARTITION.... to prj.conf

CONFIG_MAIN_STACK_SIZE=2048

# Let __ASSERT do its job
CONFIG_DEBUG=y

CONFIG_LOG=y
CONFIG_LOG_MODE_MINIMAL=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

pm_static.yml is:

littlefs_storage:
address: 0
end_address: 0x800000
placement:
before:
- end
region: external_flash
size: 0x800000

Now Im getting:

I: LittleFS version 2.5, disk version 2.0
I: FS at mx25r6435f@0:0x0 is 6 0x1000-byte blocks with 512 cycle
I: sizes: rd 16 ; pr 16 ; ca 64 ; la 32
I: /lfs1 mounted
I: Automount /lfs1 succeeded
*** Booting Zephyr OS build v3.2.99-ncs2 ***
Sample program to r/w files on littlefs
Area 1 at 0x0 on mx25r6435f@0 for 24576 bytes
/lfs1 automounted
/lfs1: bsize = 16 ; frsize = 4096 ; blocks = 6 ; bfree = 3

at least its on mx25, but the size is wrong, it should be 8mb

[IvanR]

found what was wrong. There were several issues. First and most stupid was that directive in CMakeLists.txt was set to root of project and not to boards folder.

set(PM_STATIC_YML_FILE ${CMAKE_CURRENT_SOURCE_DIR}/boards/pm_static.yml).

Next it could not find where the partition was so the device was added to pm_static.yml

littlefs_storage:
  address: 0x0
  end_address: 0x800000
  placement:
    before:
      - end
  device: mx25r64
  region: external_flash
  size: 0x800000
  filesystem: littlefs

And at the end the the 

CONFIG_PM_PARTITION_REGION_LITTLEFS_EXTERNAL=y 

was removed from prj.conf. 

Now it works....