SIGSEGV -> Communication exception -> No DepthAI device found!

nalzok

I was playing with my (potentially broken) OAK-D-IoT-75, and suddenly got the following error (I even have a crash dump in case you want to have a look, but this forum doesn't appear to support attachments?)

$ python3 depthai_demo.py
Using depthai module from:  /Users/nalzok/.local/lib/python3.9/site-packages/depthai.cpython-39-darwin.so
Depthai version installed:  2.10.0.0.dev+7a0749a61597c086c5fd6e579618ae33accec8df
Available devices:
[0] 14442C10418059D700 [X_LINK_UNBOOTED]
USB Connection speed: UsbSpeed.HIGH
Enabling low-bandwidth mode due to low USB speed... (speed: UsbSpeed.HIGH)
Creating MJPEG link for ColorCamera node and color xlink stream...
Creating MJPEG link for StereoDepth node and disparity xlink stream...
fish: Job 1, 'python3 depthai_demo.py' terminated by signal SIGSEGV (Address boundary error)

I run the command again to see if the problem is reproducible, and I got

$ python3 depthai_demo.py
Using depthai module from:  /Users/nalzok/.local/lib/python3.9/site-packages/depthai.cpython-39-darwin.so
Depthai version installed:  2.10.0.0.dev+7a0749a61597c086c5fd6e579618ae33accec8df
Available devices:
[0] 14442C10418059D700 [X_LINK_UNBOOTED]
USB Connection speed: UsbSpeed.HIGH
Enabling low-bandwidth mode due to low USB speed... (speed: UsbSpeed.HIGH)
Creating MJPEG link for ColorCamera node and color xlink stream...
Creating MJPEG link for StereoDepth node and disparity xlink stream...
Traceback (most recent call last):
  File "/Users/nalzok/Developer/depthai/depthai_demo.py", line 234, in <module>
    pv.prepare_frames(callback=callbacks.on_new_frame)
  File "/Users/nalzok/Developer/depthai/depthai_helpers/managers.py", line 261, in prepare_frames
    packet = queue.tryGet()
RuntimeError: Communication exception - possible device error/misconfiguration. Original message 'Couldn't read data from stream: 'disparity' (X_LINK_ERROR)'

Then I tried a third time

$ python3 depthai_demo.py
Using depthai module from:  /Users/nalzok/.local/lib/python3.9/site-packages/depthai.cpython-39-darwin.so
Depthai version installed:  2.10.0.0.dev+7a0749a61597c086c5fd6e579618ae33accec8df
Traceback (most recent call last):
  File "/Users/nalzok/Developer/depthai/depthai_demo.py", line 113, in <module>
    device_info = conf.getDeviceInfo()
  File "/Users/nalzok/Developer/depthai/depthai_helpers/config_manager.py", line 280, in getDeviceInfo
    raise RuntimeError("No DepthAI device found!")
RuntimeError: No DepthAI device found!

All subsequent attempts to run the demo lead to the error RuntimeError: No DepthAI device found!. I pressed the reset button several times, did a few power cycles, and even reinstalled the whole virtual environment, but the DepthAI device still cannot be found, so I guess the device is completely bricked now?

Brandon

nalzok May be. Sorry about the trouble. I think the new device is on its way to you.

nalzok

Brandon That’s fine. Let me know if you need some diagnostic information from the broken device. I mean, understanding the failure pattern might be helpful to quality assurance 🙂

erik

Thanks for reporting @nalzok ! So this is very interesting. One thing I would try is forcing the USB2 mode (python3 depthai_demo.py --usb_speed usb2). Are you using an USB hub? If so, could you try connecting the device directly to the computer? If none of these help, could you please share the hardware specs you are using (OS, CPU, motherboard)?
Thanks again, Erik

nalzok

Well, so I just reconnected the device once more, and suddenly everything works now. I can even see a depth map!

The output seems a little weird though: there is a lot of noise even if I point the camera directly to the ceiling (especially during the startup). Moreover, when I wave my hand in front of the camera, the depth map shows two interleaving hands.

I will try to do a calibration later (I don't have a printer available right now, and my screen is not big enough).

Brandon

Thanks. So big/blank surfaces (called "low visual interest" in the CV community) give passive disparity depth a hard time.

So you'll find if you post at things that have more texture (visual interest) it will do better.

So my suspicion is that one of the cameras on the bare PCB (why we should have included an enclosure) was just barely disconnected. It's super easy to accidentally do. And picking it up by the connector actually can accidentally fix this. So that is likely what happened.

nalzok

Brandon One more question: I can hear the camera making a soft "click" sound each time I run the demo. Is that normal?

Brandon

Yes. That's normal. This particular module does that during init - it's the autofocus going fully to one extent.