ModalAI VOXL2 + Smart Radio Integration Guide: Smart Radio VOXL Integration

ModalAI VOXL2 + Smart Radio Integration Guide: Smart Radio VOXL Integration

Smart Radio VOXL Integration

Updating VOXL Firmware

Older versions of VOXL’s firmware do not include the necessary USB-Ethernet driver required by the Smart Radio Helix. Make sure to update your VOXL firmware following the instructions on the website [3].

Smart Radio VOXL Setup

Fig. 1 is a system diagram showing how a Helix Smart Radio can be connected to a VOXL-based robot system. The Helix (and Wearable/OEM) variants of the Smart Radio include a USB Device port which can be connected directly to VOXL’s USB Host port. Other versions of the Smart Radio will require a USB to Ethernet adapter as described in ModalAI’s documentation [4]. 

As VOXL handles the connection to the px4 flight controller, it is not necessary to setup the Serial port on the Smart Radio. After connecting the hardware, Modify the IP address of the host machine running QGC so that it is on the subnet, for example with netmask In order to configure the IP address, you will need to access VOXL’s shell. You can do that by connecting your PC to the USB 3.0 Micro B port on the VOXL. After that, follow the steps below.

In order to access VOXL’s shell, run

# On host machine

adb shell

From VOXL’s shell, run



You will be asked which modem you are using.

What type of modem are you using?

Choose the Doodle Labs Smart Radio. You may then select between the default IP address ( or a custom one.

Enter the IP address you would like to the VOXL to use on the Doodle network:

Note: The chosen IP address must be of the form: 10.220.XXX.XXX, where XXX is a 3 digit number


Default -


1) default

2) custom

If you choose a custom IP address, you will need to modify the Smart Radios’ IP addresses to be on the same subnet as VOXL and the QGC host machine. Once you have made your selection, VOXL will configure it’s networking to enable the connection to the Smart Radio network on boot up.

Making new interface file /etc/network/interfaces

reloading systemd services

enabling voxl-modem systemd service

starting voxl-modem systemd service

DONE configuring voxl-modem

Once this is complete, running ifconfig should display a new interface, eth0
, with the IP address which you selected.

Connect to QGC from VOXL. VOXL uses voxl-vision-px4 to connect VOXL to the hostmachine running QGC. If you have not yet run voxl-configure-vision-px4, then you can do so now, and you will be asked a series of questions including the IP address of the host machine running QGC. Otherwise you can edit the voxl-vision-px4 configuration file and update qgc-ip

vi /etc/modalai/voxl-vision-px4.conf

You will then need to restart the voxl-vision-px4

systemctl restart voxl-vision-px4

Next you need to enable voxl-mavlink-server. You can do so by running voxl-configure-mavlink-server. If you plan on editing the configuration, you can edit the file /etc/modalai/voxl-mavlink-server.conf
. After that, restart the service with

systemctl restart voxl-mavlink-server

At this point, VOXL should automatically connect to QGroundControl.


ModalAI,, 10-8-2021

ModalAI Technical Docs – VOXL,, 10-8-2021


ModalAI Using USB to Ethernet with VOXL,, 10-8-2021

Additional References