VOXL 2 - D0006 Architecture (Sentinel)

Table of contents

1. VOXL2 - D0006-C11-M13-T1
   1. Hardware
      1. Summary
      2. Components
      3. HW Block Diagram
      4. HW Theory of Operation
   2. Software
      1. VOXL2 SDK 1.1.3
         1. Summary
         2. MPA Configuration Command
         3. SW Block Diagrams
         4. SW Theory of Operation

VOXL2 - D0006-C11-M13-T1

Hardware

Summary

The D0006-C11-M13-T1 configuration is used in the base Sentinel reference drone model.

• D0006 - Sentinel Family
• C11 - Image Sensor Config 11, QTY2 pair of ov7251 stereo sensors, ov7251 tracking sensor, imx214 hires sensor
• M13 - WiFi modem config
• T1 - DSMX receiver config

Components

The following core hardware is used for that configuration (note in this guide we are excluding the motor, battery, transmitter):

HW Block Diagram

Below describes the compute HW block diagram for the D0006-C11-M13-T1 configuration.

• view this drawing in fullsize, view drawing source (using this tool)
• for more information on connecting the image sensors, see video here and or image here

HW Theory of Operation

Power

The VOXL Power Module (MDK-M0041) accepts 2S-6S batteries as input, and passes this straight through to the VOXL ESC (MDK-M0117) and also regulates the voltage down to 5VDC.

Output form the power module (M0041-J1), the 5V/6A rated regulator powers VOXL2 (MDK-M0054) and provides power monitoring information over I2C (to voxl-px4 over DSP, not apps_proc) through the power connector (M0054-J4).

Debug Connections

Once powered, a user can connect to a linux based terminal though the USBC connector (M0054-J9) using Android Debug bridge (adb).

Additionally, once initially setup over adb, a user can interact with VOXL2 over a network (ssh, voxl-portal) using the Wi-Fi add-on kit (MDK-M0078).

Image Sensors

Two stereo pairs (ov7521, VGA, black and white, 30FPS) connect to VOXL2 (M0054-J6 and M0054-J8) using interposers M0076, M0074 and M0010.

A tracking sensor (ov7521, VGA, black and white, 30FPS) and hires (imx214, 4K, 30FPS) connect to VOXL2 M0054-J7 using the M0084 dual camera flex.

Flight Controller

The VOXL ESC (MDK-M0117) communicates over UART to voxl-px4 between M0117-J2 and M0054-J18.

The VOXL2 GPS/Mag/RC bind assembly (MDK-M0094) is a possible solution for GPS (UART) Mag (I2C) and RC (UART). Both communicate to voxl-px4 over a UART and I2C (exposed from DSP, not apps_proc) This kit uses Ublox Neo-M8N/IST8310 from Holybro.

The RC is Spektrum DSMX (mainly for legacy reasons, as a bunch of past product has used it. For this reason, we continued to use it. The snapdragon processors can’t make a UART RX into an TX at run time. For this reason, we have to use a GPIO to handle binding the RC, hench the little M0094 binding board you see in this assembly.)

Software

The following VOXL2 Platform Releases have been validated with the hardware above

VOXL2 SDK 1.1.3

Summary

MPA Configuration Command

To setup the VOXL SDK to use the above hardware configuration, run the MPA command listed below.

SW Block Diagrams

Below are two block diagrams covering

voxl-camera-server	- view this drawing in fullsize, view drawing source (using this tool)
voxl-px4	- view this drawing in fullsize, view drawing source (using this tool)

SW Theory of Operation

Summary

VOXL2 runs Linux (Ubuntu 18). A collection of user space applications run on bootup as systemd services to facilitate the various requirements of the architecture. These applications (open source, mainly C/C++) communicate between each other using linux named pipes using the light weight Modal Pipe Architecture.

To facilitate installation and setup, ModalAI ships Platform Releases (SDK) that allow a simple setup.

SDK

The VOXL2 SDK is a a zip file that contains an install script, the VOXL2 System Image (kernel, root file system) and the VOXL SDK, which is a collection of open source software packages.

The VOXL SDK comes with a voxl-configure-sku tool that can be used to configure the software to work out of the box on a given hardware architecture, such as this D0006.

voxl-px4

In SDK 1.1.3, voxl-px4 is based off of PX4 1.14 and located in this branch. More developer information is available in the VOXL2 PX4 Developer Guide. More user information is available in the VOXL2 PX4 User Guide.

All communications to ground control stations from voxl-px4 are facilitated through voxl-mavlink-server and voxl-vision-px4 over an IP link. See quick start video.

Below are links to some of the drivers that are called out above.

Other Services

Below are links and summaries of the other services that are expected to be running by default: