.. _usb_mass:
USB Mass Storage Sample Application
###################################
Overview
********
This sample app demonstrates use of a USB Mass Storage driver by the Zephyr
project. This very simple driver enumerates a board with either RAM or FLASH
into an USB disk. This sample can be found under
:zephyr_file:`samples/subsys/usb/mass` in the Zephyr project tree.
Requirements
************
This project requires a USB device driver, and either 16KiB of RAM or a FLASH
device.
Building and Running
********************
This sample can be built for multiple boards. The selection between a RAM-based
or a FLASH-based disk can be selected using the ``overlay-ram-disk.conf`` or
the ``overlay-flash-disk.conf`` overlays. In this example we will build the sample
with a RAM-based disk:
.. zephyr-app-commands::
:zephyr-app: samples/subsys/usb/mass
:board: reel_board
:gen-args: -DOVERLAY_CONFIG="overlay-ram-disk.conf"
:goals: build
:compact:
After you have built and flashed the sample app image to your board, plug the
board into a host device, for example, a PC running Linux.
The board will be detected as shown by the Linux journalctl command:
.. code-block:: console
$ journalctl -k -n 17
usb 2-2.4: new full-speed USB device number 29 using xhci_hcd
usb 2-2.4: New USB device found, idVendor=2fe3, idProduct=0100, bcdDevice= 0.11
usb 2-2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 2-2.4: Product: Zephyr MSC sample
usb 2-2.4: Manufacturer: ZEPHYR
usb 2-2.4: SerialNumber: 0.01
usb-storage 2-2.4:1.0: USB Mass Storage device detected
scsi host3: usb-storage 2-2.4:1.0
scsi 3:0:0:0: Direct-Access ZEPHYR ZEPHYR USB DISK 0.01 PQ: 0 ANSI: 0 CCS
sd 3:0:0:0: Attached scsi generic sg1 type 0
sd 3:0:0:0: [sdb] 32 512-byte logical blocks: (16.4 kB/16.0 KiB)
sd 3:0:0:0: [sdb] Write Protect is off
sd 3:0:0:0: [sdb] Mode Sense: 03 00 00 00
sd 3:0:0:0: [sdb] No Caching mode page found
sd 3:0:0:0: [sdb] Assuming drive cache: write through
sdb:
sd 3:0:0:0: [sdb] Attached SCSI removable disk
The disk contains a simple ``README.TXT`` file with the following content:
.. code-block:: console
This is a RAM Disk based USB Mass Storage demo for Zephyr.
Files can be added or removed like with a simple USB disk, of course within
the 16KiB limit.
578ae40761