VOXL 2 IO User Guide

Table of contents

1. Overview
   1. Summary
   2. PX4 Version Requirement
2. Limitations
   1. Supported Mixers and Airframe Setup
   2. UART ESC Compatibility
   3. PX4 Parameters
   4. Spektrum RC Binding
   5. PWM ESC Calibration
   6. VOXL 2 Firmware Update
3. Wiring Guides
   1. Host Connection
      1. VOXL 2 as Host (M0054)
      2. RB5-Flight as Host (M0052)
   2. RC Connections
      1. Using S.BUS (FrSky R-XSR)
      2. Using S.BUS (Graupner GR-16)
      3. Using Spektrum (DSMX)
   3. PWM Connection
4. Modes and LED Patterns
   1. Bootloader Mode
   2. Application Running in Waiting Mode
   3. Application Running in Standard Mode
   4. Firmware Update Mode
   5. Communication Error Mode

Overview

Summary

The VOXL 2 IO board requires a host running PX4 running the px4io module, such as VOXL 2. The IO board provides PWM outputs (8) and expands the native Spektrum RC support by adding S.BUS support (and provides passthrough Spektrum as well).

The IO board is powered from and communicates via VOXL 2’s RC port. The VOXL 2 communicates to the VOXL 2 IO board using a UART connection.

PX4 Version Requirement

ModalAI built PX4 1.12.31 is required for VOXL 2 IO and available in from the dev pkg manager package

Limitations

Supported Mixers and Airframe Setup

Airframe selection via QGroundControl is not supported.

The VOXL 2 IO has validated against quad_x and hex_x airframes only. In the current release, configuring the mixer is done manually by editing the /usr/lib/rfsa/adsp/quad_x_io.main.mix file.

Quad:

R: 4x 10000 10000 10000 0

Hex:

R: 6x 10000 10000 10000 0

UART ESC Compatibility

VOXL 2 IO has not been validated to be used in parallel to the ModalAI UART ESC yet to expose additional PWM channels while also using the ModalAI UART ESC.

PX4 Parameters

The defaults set by voxl-px4-set-default-parameters.config. Ensure you vehicle is configured correctly.

CBRK_IO_SAFETY 22027
PWM_MAIN_MAX   2000
PWM_MAIN_MIN   1060
PWM_MAIN_RATE   400
PWM_MAIN_DISARM 900

Spektrum RC Binding

The Spektrum bind feature invoked via QGroundControl does not work and needs to be ran manually from VOXL2. To enable Spektrum bind:

Connect to VOXL 2’s shell:

adb shell

Run the following commands to put Spektrum RC in bind mode.

px4-qshell px4io safety_on
px4-qshell px4io bind dsmx8

PWM ESC Calibration

NOTE: the following feature is still in beta.

For this process to work, you need to have physical access to J1 (PWM output port).

Use with caution, as this will be setting PWM outputs which could spin motors inadvertently.

REMOVE ALL PROPS. REPEAT: REMOVE ALL PROPS

Using the Sentinel drone with PWM based ESCs as an example:

• Power off the drone
• Remove the PWM cable from VOXL 2 IO connector J1
• Power on the drone
• adb or ssh onto the drone
• get prepared to re-attach the cable (but not yet)

After you do the next step, you have 10 seconds to connect the PWM cable back to J1.

• from the terminal, run px4-qshell pwm cal_backdoor

Note: you will see an timeout error message, this is OK, for example:

voxl2:/$ px4-qshell pwm cal_backdoor
INFO  [qshell] Send cmd: 'pwm cal_backdoor'
ERROR [qshell] command timed out
ERROR [qshell] Command failed

• re-attach the cable, ESCs will make a short power on jingle
• in 10 seconds, a set of beeps being lasting several seconds
• after the jingles are done, you are done

Here’s the waveform generated over time:

And the same in video, for fun ;)

VOXL 2 Firmware Update

The Firmware Update feature from host to VOXL 2 IO is currently not supported.

Wiring Guides

Host Connection

VOXL 2 as Host (M0054)

From VOXL2, connect J19 pins 9-12 to VOXL2 IO J4 pins 1-4 as shown here:

RB5-Flight as Host (M0052)

RC Connections

Using S.BUS (FrSky R-XSR)

In the following example, the FrSky R-XSR receiver is being used with MCBL-00065-1:

Using S.BUS (Graupner GR-16)

In the following example, the Graupner GR-16 receiver is being used has had it’s channel 8 setup as SBUS with MCBL-00064-1:

Using Spektrum (DSMX)

In the following example, the Spektrum SMX-SPM9745 receiver is being used with MCBL-00005-1:

PWM Connection

In the following example, the PWM Breakout Board (MCCA-M0022) and cable (MCBL-00004-1) are used to expose PWM based actuation:

Modes and LED Patterns

The VOXL 2 IO board can be in the following modes accompanied with a unique LED pattern.

• Bootloader Mode
• Application Running in Waiting Mode
• Application Running in Standard Mode
• Firmware update mode
• Communication error mode

Bootloader Mode

For the first 200ms after power on, the VOXL 2 IO is in bootloader mode. The serial firmware update could be performed during this time.

Note: this mode is very short lived an almost not perceptible to the eye.

Application Running in Waiting Mode

When the system is running and communications with VOXL 2 have not started and it is waiting, the following LED pattern can be seen.

Application Running in Standard Mode

When the system is running, the following LED pattern can be seen.

Firmware Update Mode

When the system is in firmware update mode, the following LED pattern can be seen.

Communication Error Mode

When communication errors occur, the following LED pattern can be seen.

Note: early RB5 based releases showed this mode when acting as an RC passthrough.