# FAQ

1、Why do I get the following error when running `python3 examples/depth_viewer.py` on Jetson Nano?

```bash
illegal instruction (core dumped)
```

Answer: Check your OpenCV installation. If you encounter the same error when running

```python
import cv2
```

export OPENBLAS_CORETYPE=ARMV8 (or whatever the actual hardware is) before launching python should hopefully get around
this. For example:

```bash
OPENBLAS_CORETYPE=ARMV8 python
```

If you would like to make this export permanent, you should open your .bashrc file by typing on the terminal:

```bash
nano ~/.bashrc
```

and add the following line at the end of the file:

```bash
export OPENBLAS_CORETYPE=ARMV8
```

Refer to [this post](https://stackoverflow.com/questions/65631801/illegal-instructioncore-dumped-error-on-jetson-nano)
for more information on how to resolve the issue.


2、 Why do I get the following error when running `python3 examples/depth_viewer.py`?

```text
 msg:failed to open usb device!  error: OB_USB_STATUS_ACCESS
  - type:St13runtime_error
[2023-07-04 17:09:19.891859][warning][117523][EnumeratorLibusb.cpp:342] failed to create usb device at index: 1, url:2-1.4.1-6
[2023-07-04 17:09:20.391989][error][117523][DeviceLibusb.cpp:109] failed to open usb device!  error: OB_USB_STATUS_ACCESS
[2023-07-04 17:09:20.392032][warning][117523][EnumeratorLibusb.cpp:342] Execute failure! A std::exception has occurred!
  - where:342#createUsbDevice
  - msg:failed to open usb device!  error: OB_USB_STATUS_ACCESS
  - type:St13runtime_error
[2023-07-04 17:09:20.392057][warning][117523][EnumeratorLibusb.cpp:342] failed to create usb device at index: 1, url:2-1.4.1-6
[2023-07-04 17:09:20.392072][warning][117523][ObException.hpp:40] usbEnumerator createUsbDevice failed!
Traceback (most recent call last):
  File "depth_viewer.py", line 73, in <module>
    main()
  File "depth_viewer.py", line 34, in main
    device: Device = device_list.get_device_by_index(0)
pyorbbecsdk.OBError: usbEnumerator createUsbDevice failed!
[2023-07-04 17:09:20.403747][info][117523][Context.cpp:81] Context destroyed
```

Answer: The current device does not have permission to access the device， check the PID of the current device

```bash
lsusb | grep 2bc5
```

Your output should look like this

```text
Bus 002 Device 007: ID 2bc5:your_pid_here
```

Edit`/etc/udev/rules.d/99-obsensor-libusb.rules`，add the following line

```bash
SUBSYSTEM=="usb", ATTR{idProduct}=="your_pid_here", ATTR{idVendor}=="2bc5", MODE:="0666", OWNER:="root"  GROUP:="video", SYMLINK+="you_device_name_here"
```

`you_device_name_here` is the name of the device you want to create, for example `Astra`.

Then restart the udev service

```bash
sudo udevadm control --reload-rules && sudo service udev restart && sudo udevadm trigger