Issues with D435i over USB 2.0
Hi, I'm working on an application where I'm trying to run a D435i in a pressure tight enclosure and due to the interconnect limitations, must run at USB2.0 speeds. We've had a couple of issues, the first being power negotiation with the host. We've found adding a USB2.0 Hub seems to resolve the power negotiation for the most part, the other issue we're having is a drop out after a while. Everything will work for an hour or so and then on the host machine, we get reports that the USB device is resetting and it does this perpetually, we can't get a data feed back, even with a full power cycle. We're still trying to hunt down the cause, could be power draw related or an issue with the USB hub but figured I'd check if anyone here had recommendations for best practice to get the camera to send data at 2.0 speeds while keeping the host USB controller happy.
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Hi Andrew Edwards Instead of using a USB 2 hub, you could try using a USB 2 cable instead of the official USB 3 one supplied with the camera and connecting the camera directly to your computer's USB port. Because a USB 2 cable lacks extra wires that enable a device to operate at USB 3 speed, the camera should operate in USB 2 mode when attached to a USB 2 cable.
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Hi Marty, the issue we had with this setup seemed to be related to host's USB controller and power negotiation. The host would limit the available power to USB 2.0 spec (500mA) which caused issues with the camera. The addition of a "dumb" USB hub in the middle seemed to resolve that issue.
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Thanks very much for the additional information.
USB hubs have their own dedicated USB controllers, which will likely be a different brand to the USB controller that the computer's manufacturer chose for their built-in ports. And some USB controllers work better with RealSense cameras than others.
If your enclosure was able to use a mains electricity powered (active) USB 3.1 hub then it would be more stable than an unpowered (passive) hub as it would draw power from the mains socket instead of the computer's USB port (which in turns draws from the computer's power supply unit). The hub would also have its own USB controllers independent of the ones on the computer.
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