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# Using the USB Host port

Note This section contains Linux BSP documentation for kernel v4.1. Click here for v4.9 BSP documentation.

The USB Host device driver exposes the connected devices through the file system at /dev/bus/usb/.

Linux identifies USB devices as soon as they are plugged in. Depending on the log level, the serial console may display a message reporting that the USB device has been plugged in. For example, plugging in a USB memory stick displays this message:

    sd 1:0:0:0: [sda] 1970176 512-byte logical blocks: (1.00 GB/962 MiB)
    platform fixedregulator.25: Driver reg-fixed-voltage requests probe deferral
    sd 1:0:0:0: [sda] Write Protect is off
    sd 1:0:0:0: [sda] Mode Sense: 0b 00 00 08
    sd 1:0:0:0: [sda] No Caching mode page found
    sd 1:0:0:0: [sda] Assuming drive cache: write through
    sd 1:0:0:0: [sda] No Caching mode page found
    sd 1:0:0:0: [sda] Assuming drive cache: write through
     sda: sda1
    sd 1:0:0:0: [sda] No Caching mode page found
    sd 1:0:0:0: [sda] Assuming drive cache: write through
    sd 1:0:0:0: [sda] Attached SCSI removable disk
    FAT-fs (sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

If no message is displayed on the console, you can view all the system messages by printing the contents of the system log file:

    # cat /var/log/messages

To get a list of the connected USB devices on the USB Host port, use the command lsusb:.

    # lsusb
    Bus 001 Device 004: ID 0781:5530 SanDisk Corp. Cruzer
    Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
    Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

To get more detailed information on the connected USB device, use

    # lsusb -D /dev/bus/usb/001/004

where the first numbered folder corresponds to the bus number and the second to the device number.

### USB memory sticks

Linux automatically mounts USB memory sticks' partitions as /media/sdxN, where x is a letter and N the index of the partition (starting at 1).

If Linux does not automatically mount a partition, you can mount it manually. Use the mount command, passing the corresponding file system type with -t option and the mount point folder; for example, for a FAT32 file system:

    # mkdir /media/myusb
    # mount -t vfat /dev/sda1 /media/myusb

### Other USB input devices

Other USB input devices, such as a mouse or a keyboard, can be used immediately after being connected. For example, connect a keyboard to a USB connector. Then, run the following command to dump the keyboard key events:

    # hexdump /dev/input/event0

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Using the USB Host port updated on 22 January 2018 02:43:37 PM