PX4 -> QGC connection through USB for VOXL2

[Alex Kushleyev]

@bendraper , If you see an ethernet connection to VOXL2 show up on your Windows host, then the usb gadget is properly configured on VOXL2. Perhaps something else is going on. Are you assigning a static ip on your host that is on the same subnet as VOXL2?

You should try to repeat the same test on a linux machine (or virtual machine) to see if you can get a working connection.

Alex

[bendraper]

@Alex-Kushleyev Yea I can get a connection on a linux machine with no issue. I do need to get it working on a Windows machine for my purposes though. I definitely have the static IP setup correctly. I tried populating the gateway and also not populating it. I confirmed in powershell that there is indeed a route present for that traffic, but they do not want to communicate with each other. Some quick research seems to suggest Windows is very finicky with the CDC NCM protocol and it is more suited to work with an RNDIS interface. Were you able to ping/ssh to a voxl via an ethernet interface on the usb-c port to a windows machine using just the commands you listed above in this post?

[Alex Kushleyev]

@bendraper , I just tried this on a Windows 11 VM and even though i was able to see a network device appear in the VM and i configured the IPv4 properties, I cannot ping or ssh. It seems consistent with what you are seeing.

[bendraper]

@Alex-Kushleyev It looks like someone on the forums maybe had success setting up the interface as an RNDIS gadget. I'll try to mess with it some more but let me know if you find a solution. Thanks!

[Alex Kushleyev]

@bendraper , I will ask around.

[bendraper]

@Alex-Kushleyev So I can see a gadget functionality called gsi.rndis (I'd expect something called rndis.0 or something but maybe that is irrelevant) but when I change the line in /sbin/usb/compositions/901D to use gsi.rndis instead of ncm.0, my network interface on windows disappears and I can no longer ADB. I'd imagine there's something at the kernal level that doesn't like that but I'm out of my wheelhouse there. Setting it back to ncm.0 returns to the previous state but still cannot ping. Wireshark doesn't even see anything happening over that interface

[Zachary Lowell 0]

Hi All - gonna spend a bit of time looking into this today so I can get some context on the problem.

Zach

[qt]

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[qt]

This post is deleted!

[qt]

@Alex-Kushleyev
That's not perfect but I created a shell script based on https://docs.modalai.com/qgc-via-adb/ for the drone configuraiton.
For my PC configuration, I created an udev rule to force an interface name since usb0 is renamed in "enx******". My udev rule can only work with my drone (I think). To define IP address, I add a conf file in /etc/systemd/network/
I have only tested on my linux and it works perfectly :

#!/usr/bin/env bash
set -euo pipefail

# See ModalAI doc : https://docs.modalai.com/qgc-via-adb/

UDEV_RULE_DRONE="/etc/udev/rules.d/80-usb-ncm.rules"
UDEV_RULE_PC="/etc/udev/rules.d/99-voxl-usb-ncm.rules"
SYSTEMD_CONF_PC="/etc/systemd/network/10-voxl0.network"

USB_COMP_QUALCOM="/sbin/usb/compositions/901D"

# Network configuration
USB_IFACE="usb0"
USB_NET="192.168.7.0/24"
PC_IP="192.168.7.1"
DRONE_IP="192.168.7.2"
NM_CONN_NAME="voxl-usb-ncm"

show_help() {
    echo "Usage: $0 [--pc] [--drone] [--uninstall]"
    echo
    echo "Enable USB NCM networking for ModalAI VOXL / Starling 2 Max"
    echo
    echo "Options:"
    echo "  --pc         Configure host PC only"
    echo "  --drone      Configure drone via adb only"
    echo "  --uninstall  Remove configuration"
    echo "  --help       Show this help"
    echo
    echo "Defaults: if neither --pc nor --drone is provided, both are processed."
}

do_pc_install() {
    echo "[INFO][PC] Installing udev rule for VOXL USB NCM"

    cat > "$UDEV_RULE_PC" <<EOF
SUBSYSTEM=="net", ACTION=="add", ATTRS{idVendor}=="05c6", ATTRS{idProduct}=="901d", ATTRS{serial}=="890d035c", NAME="voxl0"
EOF

    echo "[INFO][PC] Creating systemd-networkd config for voxl0"

    cat > "$SYSTEMD_CONF_PC" <<EOF
[Match]
Name=voxl0

[Network]
Address=${PC_IP}/24
LinkLocalAddressing=no
IPv6AcceptRA=no
EOF

    echo "[INFO][PC] Reloading udev rules"
    udevadm control --reload-rules
    udevadm trigger

    echo "[INFO][PC] Restarting systemd-networkd"
    systemctl restart systemd-networkd

    echo "[INFO][PC] PC installation complete"
}

do_pc_uninstall() {
    echo "[INFO][PC] Removing PC configuration"

    if [ -f "$UDEV_RULE_PC" ]; then
      rm -f "$UDEV_RULE_PC"
      echo "[INFO][PC] Removed udev rule"
    fi

    if [ -f "$SYSTEMD_CONF_PC" ]; then
      rm -f "$SYSTEMD_CONF_PC"
      echo "[INFO][PC] Removed systemd-networkd config"
    fi

    echo "[INFO][PC] Reloading udev rules"
    udevadm control --reload-rules
    udevadm trigger

    echo "[INFO][PC] Restarting systemd-networkd"
    systemctl restart systemd-networkd

    echo "[INFO][PC] PC uninstallation complete"
}

do_drone_install() {
    echo "[INFO][DRONE] Enabling USB NCM networking on VOXL via adb"

    adb root
    adb remount

    echo "[INFO][DRONE] Updating USB composition in Qualcomm script \
$USB_COMP_QUALCOM configure the usb gadget with \
the addition of the function NCM"
    echo "[INFO][DRONE] In $USB_COMP_QUALCOM, \
add the line 'ln -s functions/ncm.0 configs/c.1/f3 2>/dev/null | true' \
just after the line 'ln -s functions/ffs.adb configs/c.1/f2'"
    
    adb shell "sed -i '/ln -s functions\\/ffs.adb configs\\/c.1\\/f2/a \
    \\        ln -s functions\\/ncm.0 configs\\/c.1\\/f3 2>\\/dev\\/null | true' \
    $USB_COMP_QUALCOM"

    echo "[INFO][DRONE] Creating udev rule $UDEV_RULE_DRONE for usb0 with IP ${DRONE_IP}"
    
    adb shell "cat << 'EOF' > $UDEV_RULE_DRONE
ACTION==\"add\", SUBSYSTEM==\"net\", KERNEL==\"usb0\", \
RUN+=\"/bin/sh -c 'sleep 2; /sbin/ifconfig usb0 ${DRONE_IP} netmask 255.255.255.0 up'\"
EOF"

    echo "[INFO][DRONE] NCM enabled — reboot required"
}

do_drone_uninstall() {
    echo "[INFO][DRONE] Removing NCM configuration"

    adb root
    adb remount

    echo "[INFO][DRONE] Removing udev rule $UDEV_RULE_DRONE"
    adb shell "rm -f $UDEV_RULE_DRONE || true"

    echo "[INFO][DRONE] Reverting USB composition (901D)"
    adb shell "
    sed -i '/ln -s functions\\/ncm.0 configs\\/c.1\\/f3/d' \
    $USB_COMP_QUALCOM
    "

    echo "[INFO][DRONE] USB NCM configuration removed"
    echo "[INFO][DRONE] Reboot required to fully apply changes"
}


# Arg parsing
TARGET_PC=false
TARGET_DRONE=false
DO_UNINSTALL=false

for arg in "$@"; do
  case "$arg" in
    --help) show_help; exit 0 ;;
    --pc) TARGET_PC=true ;;
    --drone) TARGET_DRONE=true ;;
    --uninstall) DO_UNINSTALL=true ;;
    *)
      echo "[ERROR] Unknown argument: $arg";
      show_help;
      exit 1 ;;
  esac
done

# Default to both if none selected
if ! $TARGET_PC && ! $TARGET_DRONE; then
  TARGET_PC=true
  TARGET_DRONE=true
fi

# Execute
if $DO_UNINSTALL; then
  $TARGET_PC && do_pc_uninstall
  $TARGET_DRONE && do_drone_uninstall
else
  $TARGET_PC && do_pc_install
  $TARGET_DRONE && do_drone_install
fi

echo "[INFO] All done."
``