SDK 1.8 / PX4 1.18: VOXL ESC telemetry is valid in PX4 but MAVLink reports all motors offline

[simiken1234]

Hardware: Custom drone, VOXL 2 M0054
SKU: TF-M0054-4-V1-C11

Software version:

system-image: 1.8.09-M0054-14.1a-perf-20261009
hw platform:  M0054
voxl-suite:   1.8.0

Relevant packages:
voxl-px4            1.18.0-1.0.9
voxl-mavlink-server 1.4.21-202610161525
voxl-px4-params     0.9.35
voxl-esc            1.6.5

Configuration / services:

ESC=VOXL_ESC

voxl-px4            Enabled, Running
voxl-mavlink-server Enabled, Running

What I am trying to do:

View normal ESC health and telemetry in QGroundControl's ESC Status Overview.

What actually happens:

QGC shows ERR and all four motors as offline. The vehicle can still arm, motors can be spun from the Actuators page, and flight-control outputs work.

PX4 itself receives valid ESC telemetry. px4-listener esc_status shows all four ESCs online and fresh:

esc_online_flags: 15 (0b1111)
esc_armed_flags: 15 (0b1111)
esc_count: 4
esc_connectiontype: 1

ESC 0-3: fresh timestamps, 12.497-12.513 V, 32-39 C,
         esc_errorcount: 0, failures: 0

However, each of the four reports has:

actuator_function: 0

I captured the MAVLink packets leaving the VOXL for the GCS. ESC_INFO and ESC_STATUS are transmitted, so this is not a voxl-mavlink-server forwarding issue. But they contain:

ESC_INFO:   count=4, info=0 (all ESCs offline)
ESC_STATUS: RPM/voltage/current all zero

I traced this to the PX4 MAVLink ESC stream: it now remaps and exports telemetry only for reports with actuator_function set to Motor1..MotorN. The voxl_esc driver publishes valid esc_status telemetry and online flags, but does not populate esc_status.esc[i].actuator_function, so all reports are filtered out before MAVLink serialization.

This appears to be a regression caused by the PX4 MAVLink ESC stream change in commit efbc9e64 (mavlink: esc: fix ESC_STATUS and ESC_INFO message emission, November 2025). That commit is included in the installed v1.18.0-1.0.9 source tag. Before that change, the MAVLink stream forwarded the esc_status arrays and esc_online_flags directly, so it did not depend on actuator_function.

Steps to reproduce:

1. Boot a VOXL 2 using the versions above with ESC=VOXL_ESC.

2. Connect QGroundControl to voxl-mavlink-server on UDP port 14550.

3. Open the ESC Status Overview. All four motors show offline / ERR.

4. On the VOXL, run:

   px4-listener esc_status
   

5. Observe that ESC telemetry and online flags are valid, while actuator_function is 0 for ESC 0-3.

Logs / pictures:

I can provide the full voxl-version, voxl-inspect-services, px4-listener esc_status output, and the MAVLink packet capture.

Could you confirm whether voxl_esc should populate each esc_status.esc[i].actuator_function from the configured VOXL_ESC_FUNC1..4 motor mapping, and provide or point me to a fix for the SDK 1.8 / PX4 1.18 package?

[Eric Katzfey]

Thanks for reporting this! A fix is has been pushed. You can find an updated voxl-px4 package here: http://voxl-packages.modalai.com/dists/qrb5165/dev/binary-arm64/voxl-px4_1.18.0-1.0.13-202610190909_arm64.deb