Starling 2 - VOXL2 IMU Clock Line Failure after Heatsink Maintenance

[LuisRzdearbulo 0]

Hello everyone,
We are running a Starling 2 (SDK 1.8.06) for a commercial pilot deployment. After performing a careful sensor maintenance and mounting the official heatsink back on the VOXL2 (M0054), PX4 is completely blocked and unable to pass pre-flight checks.

The voxl-health-check reports sensor_accel and sensor_gyro as 0, 0, 0 (result: False). Checking journalctl -u voxl-imu-server, we are getting the exact hardware fault described in your official forums:

trying ICM42688 on bus 3 ERROR in test_basic_read, read the same values twice WARNING initializing 42688, clock line may be disconnected, trying to turn it off 42688 IMU works without clock line, this indicates PCB damage

We have already tried loosening the heatsink screws carefully to release any potential mechanical PCB stress, performing cold boots, and restarting the services, but the error persists. The clock line buffer seems permanently damaged, rendering the autopilot blind.

What can we do?

Thank you for your swift support,

[Alex Kushleyev]

@LuisRzdearbulo-0 , can you please let us know which heat sink you mounted to VOXL2? Can you please share a picture?

[LuisRzdearbulo 0]

Hi @Alex-Kushleyev ,

My apologies for the confusion. To be precise: we didn't add any third-party or custom heatsink. However, to replace the damaged 4K and ToF camera flex cables, we did have to unscrew the VOXL 2 board from the frame to access the connectors safely.

Once the new cables were plugged in and the board was screwed back into place, the ICM42688 PCB damage / clock line disconnected error appeared.

I have attached the pictures of the current assembly inside our Starling 2 so you can verify that the M0054 board, the integrated cooling plate, and all camera flex cables are correctly in place and undamaged from the outside.

Given the log and the pictures, what do you propose we do to get the drone operational again?

Regards,
Luis

[LuisRzdearbulo 0]

Hi @Alex-Kushleyev,

I wanted to follow up on this as we are currently in a critical phase of our commercial pilot deployment, and having the Starling 2 grounded is severely impacting our timeline.

Given the voxl-imu-server logs and the pictures provided, is there any specific software workaround, service configuration, or hardware adjustment we can try to restore the IMU functionality?

If you determine that the board requires factory repair or replacement, please let us know how we can expedite the RMA process to get operational again as soon as possible.

Thank you for your support,
Luis

[Alex Kushleyev]

Hello @luisrzdearbulo-0 ,

Since the IMU clock stopped functioning after disassembly / re-assembly of the drone, it is likely that a small component (clock buffer) was damaged in the process. If that is the case, fixing it yourself would be extremely difficult without proper equipment and experience. Also, unfortunately, we do not offer repair services for such cases.

You have two options:

Option 1

configure px4 to use IMU without the clock signal. you need to change the following two files and re-build voxl-px4:

• https://github.com/modalai/px4-firmware/blob/voxl-dev/boards/modalai/voxl2-slpi/src/drivers/icm42688p/ICM42688P.hpp#L63
• as a result, the IMU will use its own built-in clock source, which may be slightly off from real clock, so the samples won't be generated at the true desired rate (8000Hz, for example), however the effect most likely wont be noticeable (many flight controllers do not use IMU clock sync).

Note that if the clock buffer chip is broken, then the second IMU will also not work (which is used for VIO), so the IMU server for the Apps Proc IMU will also need to be re-built with clock disabled : https://gitlab.com/voxl-public/voxl-sdk/services/qrb5165-imu-server/-/blob/master/server/src/icm42688.cpp?ref_type=heads#L54

• as a test, you should check if your apps proc IMU is running or also reporting clock issues (see voxl-imu-server and voxl-inspect-imu on voxl2)

Option 2

replace the VOXL2 board to get back the original functionality - I am afraid there is no other alternative.

Alex

[LuisRzdearbulo 0]

Hi @alex-kushleyev ,

Thank you for the clear guidance and the two options.

We have already applied Option 1 for the Apps Proc IMU:

Rebuilt and installed voxl-imu-server with #define EN_RTC disabled
voxl-inspect-imu imu_apps now reports healthy accel/gyro data (~9.8 m/s² at rest)
No more “clock line / PCB damage” warnings on that path
However, PX4 flight IMU is still down:

px4-listener sensor_accel / sensor_gyro publish no samples
pre_flight_checks_pass: false
Platform: Starling 2 / VOXL2 M0054, system-image 1.8.06, voxl-px4 1.14.0-2.0.133
We are blocked on rebuilding voxl-px4 / SLPI because we do not have access to the Hexagon SDK (asset 184) on our side, and we cannot redistribute it.

Could you please help with one of the following?

Provide a prebuilt voxl-px4 .deb (compatible with our 1.8.06 / 2.0.133 line, or current recommended) with EN_RTC disabled in the SLPI ICM42688P driver, or
Confirm the exact Hexagon SDK package / process we should use if we must build it ourselves, or
If software is not feasible, please advise on the fastest path for VOXL2 board replacement / RMA for this commercial pilot.
Happy to share logs, voxl-version, and package list if useful.

Thanks again for your support,
Luis

[Eric Katzfey]

Our downloads page was recently updated and in the process the Hexagon SDK download file sdk.tgz was locked. We'll get that fixed and let you know when it is ready.