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USB Net

Most of radxa products have reserved a USB port as an OTG port, it also a adb debug port when runuing Android. You can consult the port definitions of the corresponding products. You can set up a shared network between two products by connecting their OTG ports. Now officially supported for latest linux and android images.

Preparations​

Cable: Before you start, you will need one USB-A to USB-A cable to connect two SBCs.

Software: If your SBC has not the latest software, connect you SBC to internet and type the following command:

sudo apt update && sudo apt full-upgrade

Service: After updating software, you need to start the radxa-usbnet service:

sudo systemctl enable --now radxa-usbnet

Status: Typing the command to confirm if the service is running:

sudo systemctl status radxa-usbnet.service

The service active status is usually active(exited) when running.

OTG Settings​

At first, connect the two SBC OTG ports by USB-A to USB-A cable. Device identity of this shared network depends on what overlay you enable,the host machine shares the network to device mahine. The host machine enable this overlay:

[*] Set OTG port to Host mode

The device machine enable this overlay:

[*] Set OTG port to Peripheral mode

Reboot after enable options.

To the Host machine​

For sharing the network to device machine, host machine need to connect to the external network, both wired and wireless networks are available. Next, we need to set up a shared adapter for the device machine connection, which can be set on the KDE Desktop and Terminal. This guide you set it on terminal:

Set shared adapter:

Before operating, confirm if there is a new networkcard device:

ip a

The name of it may be different:

3: enxca5bfb533dd4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether ca:5b:fb:53:3d:d4 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::b989:8daf:feb5:f020/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

If there is not a new network card, you may need to set overlay once again.

Network Manager Tool is the recommended tool to manage the network, typing the command to open the interface:

sudo nmtui

After identification, the setting interface appears:

                              NetworkManager TUI

                            Please select an option

                            Edit a connection
                            Activate a connection
                            Set system hostname

                            Quit

                                              <OK>

Select Edit a connection -- <Add> to add a Ethernet adapter: add adapter Of the many options, we only need to fill in two of them:

        Device____  # Enter the third network card name you get by 'ip a', like: enxca5bfb533dd4
        IPv4 CONFIGURATION <Shared> # Change <Automatic> to <Shared>

Save the configuration and return to setting interface to Activate a connection, select the option you just add. It would be following if you apply it right:

                USB Ethernet
                    * Ethernet connection 1

Confirm adapter setting: After you settings, check if there is a IP address of third network card:

ip a

The expected output result is like following:

3: enxca5bfb533dd4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether ca:5b:fb:53:3d:d4 brd ff:ff:ff:ff:ff:ff
    inet 10.42.0.1/24 brd 10.42.0.255 scope global noprefixroute enxca5bfb533dd4
       valid_lft forever preferred_lft forever
    inet6 fe80::e37c:5ced:58a8:ec32/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

If it's similar with your result, time to set up device machine.

To Device machine​

Enable usb network connection: Relative to Host machine, it woulb be easy for device machine settings. At first, enable the Set OTG port to Peripheral mode overlay and start the radxa-usbnet service, reboot. Typing ip a to confirm if a new device named usb0 like the following added:

3: usb0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 76:c7:9d:9e:d5:da brd ff:ff:ff:ff:ff:ff

If not, check previous steps: reopen the overlay (Don't forget to reboot.) and restart the usbnet service.

Set up usbnet adapter: Next, set up the adapter as set up the Host device: Open the Network Manager Tool:

sudo nmtui

Select Edit a connection -- <Add> to add a Ethernet adapter:

Only the Device option should be modify, type 'usb0':

Device usb0

Other options remain default. Save the configuration.

Connect to Host device:

Return to setting interface to Activate a connection, select the option you just add.

                Ethernet (usb0)
                    Ethernet connection 1

It would take a few seconds to connect to Host device.

Check the connection:

Check if usb0 get the IP address like following:

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether f2:44:7d:ac:20:85 brd ff:ff:ff:ff:ff:ff
3: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 76:c7:9d:9e:d5:da brd ff:ff:ff:ff:ff:ff
    inet 10.42.0.46/24 brd 10.42.0.255 scope global dynamic noprefixroute usb0
       valid_lft 3597sec preferred_lft 3597sec
    inet6 fe80::1031:1ee2:bcee:4855/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

If the Host machine connect to ethernet, Device machine can also connect now.