Hey @shimizuakihiko - quick clarification first: the OAK devices shows up as USB2 only in bootloader. After DepthAI sends firmware it disconnects and re-enumerates as USB3.
You can check speed like this:
import depthai as dai
d=dai.Device()
print(d.getUsbSpeed())
If it still reports HIGH on the Pi 4, this points to the host side. The device always tries SuperSpeed if the host negotiates it. I know some Pi 4 running ubuntu had problems with VL805 controller. I think rpi-eeprom-update should fix this, but check online... Two more things you can try:
-Try the camera on a desktop/laptop USB3 port. Does it come up as SUPER there?
-Power it through a powered USB3 hub or a USB-C Y-splitter (data to the Pi, power from a separate 5 V source) to rule out Pi power/negotiation quirks.
Thanks,
Oskar
