Issue: USB MSC with FATFS on nRF54H20 External Flash (Write Error & SCSI Opcode 0xa1)

[kile.gc]

Description: I am implementing USB Mass Storage with a FAT filesystem on external MX25UW63 flash (via EXMIF) using the nRF54H20 DK (NCS v3.2.0).

Setup:

• Board: nRF54H20 DK

• SDK: nRF Connect SDK v3.2.0

• Reference: zephyr/samples/subsys/usb/mass

Configuration:

nrf54h20dk_nrf54h20_cpuapp.overlay:

/delete-node/ &storage_partition;

&exmif {
	status = "okay";
};

&gpio6 {
	status = "okay";
};

&mx25uw63 {
	status = "okay";

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

		storage_partition: partition@0 {
			label = "storage";
			reg = <0x00000000 0x00020000>;
		};
	};
};

/ {
	msc_disk0 {
		compatible = "zephyr,flash-disk";
		partition = <&storage_partition>;
		disk-name = "NAND";
		cache-size = <4096>;
	};
};

nrf54h20dk_nrf54h20_cpuapp.conf:

CONFIG_APP_MSC_STORAGE_FLASH_FATFS=y

Error Log:

*** Booting nRF Connect SDK v3.2.0-5dcc6bd39b0f ***
*** Using Zephyr OS v4.2.99-a57ad913cf4e ***
Area 0 at 0x0 on mx25uw6345g@0 for 131072 bytes
[00:00:00.024,795] <inf> flashdisk: Initialize device NAND
[00:00:00.024,800] <inf> flashdisk: offset 0, sector size 512, page size 65536, volume size 131072
[00:00:00.024,806] <err> flashdisk: Cache too small (4096 needs 65536)
[00:00:00.024,812] <err> fs: fs mount error (-5)
[00:00:00.024,816] <err> main: Failed to mount filesystem
[00:00:00.024,915] <wrn> udc_dwc2: VBUS is not ready, block udc_enable()
[00:00:00.060,241] <wrn> udc_dwc2: Experimental DMA enabled
[00:00:00.060,287] <inf> main: The device is put in USB mass storage mode
[00:00:00.403,512] <inf> usbd_msc: Enable
[00:00:00.403,577] <inf> usbd_msc: Bulk-Only Mass Storage Reset
[00:00:01.456,398] <err> usbd_msc: Unknown SCSI opcode 0xa1

Current Status:

I initially had a cache error, which I resolved by increasing the cache size to 65536. However, I am now facing two issues:

1. Write Failure: When I try to create a file on the disk, the operation fails with the following log:

   [INSERT FILE CREATION ERROR LOG HERE]
   

2. SCSI Error: I also see this error in the logs:

   [00:00:01.594,387] <err> usbd_msc: Unknown SCSI opcode 0xa1
   

Questions:

• What could be causing the file creation/write failure?

• What does Unknown SCSI opcode 0xa1 mean in this context? Is it critical?

Any advice is appreciated.

[Simonr]

Hi again

1. That must be because a 4096 cache size is too small for the FS.

2. I see from the log here that the device is initialized as a NAND device, but the external flash you're using ( the MX25UW63) is a NOR flash series device. Or have you just named the disk NAND? You're using the onboard external flash device, correct? If so, can you check in the nRF Connect for Desktop board configurator app that the External flash is powered by setting the switch here to ON 

Best regards,

Simon

[kile.gc]

Hi Simonr,

Thanks for the help. I tried turning on the External Flash power in the board configurator, but I’m still getting the same error.

A few follow-up points:

1. Cache Size: Thanks for explaining the cache. I’m still confused why other Nordic devices work fine with a smaller cache. Is this because of the MCU I'm using, or is it because of the Flash chip itself?

2. NAND Name: The "NAND" name in the log is just a label I gave the disk so the device knows where to mount the USB. It's not actually a NAND flash.

3. Project Files: I’ve attached my project files. Could you try running this on your side to see if you get the same error?

0020.mass.zip

Best regards,
Kittitouch