USB

The OVP8xx VPU devices have two separate USB interfaces:

  1. USB Type A USB 3 interface

  2. USB Type B USB 2 interface

Only the USB-A interface is available to the user. The USB-B interface is only used for debugging by ifm users.

USB-A interface use cases

USB mass storage devices

The USB Typ A interface can be used by the developer or end user to connect USB mass storage devices such as USB sticks and external USB SSD devices.

USB Mass Storage Supported File System Formats

The following file system formats are supported for the external storage devices mentioned above:

  • FAT32

  • EXT4

See the limitations imposed by the use of EXT4 below

Other USB mass storage devices

Other USB mass storage devices that require the installation of additional drivers may be functional if the drivers are installed within the respective Docker software containers. ifm does not provide official support for these devices - the user may use them in development / production use cases at his own risk. Possible compatibility limitations due to updates of the embedded firmware may require updates of the device drivers in the user’s software containers. No continuous compatibility over embedded FW versions is assured.

USB Cameras

From the firmware version 1.4.30 and above, the USB cameras will be assigned to /dev/video0 node by the VPU. USB cameras like webcams are only tested which uses the default v4l2 framework on linux kernel. It should be noted that user cannot access the V4L devices or /dev/video0 node directly on the VPU without Docker container. To make use of the nodes, please pass the respective video device node to the Docker container using the flag --device.

If the USB camera device needs any special drivers, they should be installed in a Docker container and should be tested.

Example: How to use USB web camera on VPU using Docker container

  • Install ffmpeg and v4l-utils in the Docker container by copying the following lines in your Dockerfile.

RUN apt-get update && \
    apt-get install -y ffmpeg \
    v4l-utils

  • Run the Docker container in the interactive mode

$ docker run -ti -v $(pwd):/home/ifm/ --device=/dev/video0:/dev/video0:rwm <docker-image-name>

  • Capture a frame using ffmpeg tool inside Docker container

root@<docker_id>$ ffmpeg -f v4l2 -video_size 1280x720 -i /dev/video0 -frames 1 out.jpg

  • A image out.png will be created in the home folder.

USB hubs

The use of USB hubs is at the user’s own risk.

There is no guarantee of compatibility or support for hubs. They may be functional for standard low power devices. Devices with higher power consumption may overload the power available via the USB-A interface and damage the OVP8xx VPU device.

Advanced “USB network topologies” may not be supported by the OVP8xx VPU devices. The USB interface is defined to be used by a single USB client device.

Other USB devices: USB HID, USB network adapters, …

Other USB devices such as:

  • USB mice

  • USB keyboards,

  • Generic USB input devices such as controllers,

  • USB-to-Ethernet network devices

  • USB sensors are not supported by the OVP8xx VPU device.

These devices may be (partially) functional if their respective drivers are included by default in the embedded Linux OS or are installed in an appropriate Docker software container. There is no guarantee of compatibility or support for such external hardware devices.

Access to external HID USB devices such as USB mice, keyboards, controllers, etc. may be restricted based on OEM oem user groups. The OEM user is not part of the dialout group and is therefore restricted on its interactions with such HID and further USB devices. Adding the OEM user to other groups is not possible. If such access is required, please get in contact with the ifm robotics support team.

The OEM users groups are:

$ groups oem
oem docker systemd-journal

Additional Ethernet interfaces via USB-to-Ethernet adapters are not supported by the OVP8xx VPU devices.

Additional sensor devices, such as generic USB sensors are not supported by the OVP8x VPU devices.

Using a USB drive with the VPU

It is possible to increase the VPU memory size by utilizing USB thumb drives or USB SSDs on the USB-A interface. To use any USB storage device, it is necessary to mount the drive first.

Note

The USB auto mount service mounts your USB mass storage device to /run/media/system/<USB_name>/. See the details below.

Preparing the USB drive

The VPU’s operating system supports two file formats:

  • FAT32

  • EXT4

These can be auto-mounted via the mount command and its respective daemon.

FAT32

For FAT32 formatted devices no additional steps are required. It can be directly mounted via the auto-mount daemon to the VPU.

EXT4

For EXT4 formatted devices the user needs to perform additional steps to match the OEM users uid and gid on the VPU’s embedded OS. Otherwise only read permissions are granted when mounting the USB storage device. This is a design that is introduced by the handling of access rights to EXT4 formatted devices on Linux systems. If you are an experience EXT4 user feel free to skip the following instructions steps:

Format USB mounting preparation (EXT4 only)

Option 1:

“The crude way”

The easiest option is to mount the EXT4 formatted device to your Linux laptop of choice and relax the write and read permissions to be accessible by any user:

  1. Mount the SSD to your laptop

  2. Change the mount point to be accessible by all users:

user@laptop:~$ chmod 777 /media/<mount_point>

Please be aware that the chmod command only affects the existing files within /media/<mount_point>.

Option 2:

“Setting the VPU’s OEM user UID and GID specifically”

Please be aware that setting user specific GID and UID has to be done PER user. This means, that is has to be done for the OEM user on the VPU to write to the device, as well as any specific users created inside your own Docker container.

Below an exemplary workflow is shown for setting the VPU’s OEM users UID and GID.

On the VPU:

  1. Find out the requested users UID and GID on the VPU or inside the Docker container

oem@o3r-vpu-c0:~# id -u oem
989
oemt@o3r-vpu-c0:~# id -g oem
987

On your Linux laptop of choice:

  1. Change the USB mount point on your Linux Laptop via chown

user@laptop:~$ sudo chown 989:987 -R /media/<mount_point>

.. note:: Please be aware that changing the GID and UID mount points may result in missing read access on your laptop. To restore read access on your laptop to the USB storage device, change the GID and UID back to match your personal user accounts ones.

Plug in and mounting

After plugging in the drive, the mount is started by using the command mount

o3r-vpu-c0:~$ mount
proc on /proc type proc (rw,relatime)
none on /dev type devtmpfs (rw,relatime,size=1578060k,nr_inodes=394515,mode=755)
sysfs on /sys type sysfs (rw,relatime)
/dev/mmcblk0p1 on / type ext4 (rw,relatime,data=ordered)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup2 on /sys/fs/cgroup/unified type cgroup2 (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/debug type cgroup (rw,nosuid,nodev,noexec,relatime,debug)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /var/volatile type tmpfs (rw,relatime)
/dev/mmcblk0p33 on /opt/ifm/data type ext4 (rw,relatime,data=ordered)
overlay on /etc/systemd/network type overlay (rw,relatime,lowerdir=/etc/systemd/network,upperdir=/opt/ifm/data/overlayfs/upper/network,workdir=/opt/ifm/data/overlayfs/work/network)
tmpfs on /run/user/989 type tmpfs (rw,nosuid,nodev,relatime,size=392056k,mode=700,uid=989,gid=987)
systemd-1 on /run/media/system/IFM type autofs (rw,relatime,fd=79,pgrp=1,timeout=3,minproto=5,maxproto=5,direct)

If the mount is successful you can find the drive at /run/media/system/<USB_name>/.

o3r-vpu-c0:~$ ls -la /run/media/system/IFM/
total 957660
drwxrwxrwx 6 oem  oem       4096 Jan  1  1970 .
drwxrwxrwx 3 root root        60 Feb  7 15:54 ..
...