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OPi PC: USB Hub with external power supply - Any experience?

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Post time 2016-6-3 17:46:21 | Show all posts |Read mode
Hi,

After having some trouble with a bus-powered USB hub on the Orange Pi PC, I am thinking about buying an externally powered hub for connecting my USB devices.

Has anyone of you experience with the voltage feedback that these hubs tend to send to the upstream USB port (the OPi PC, that is)? I see there are dedicated powered USB hubs for the Raspberry Pi, which seem to have the Vbus line cut, because the Raspberry Pi obviously does not like to be powered via the "real" USB host port (I think because it bypasses a fuse).

Will my OPi PC be powered by the voltage fed into the USB host port? Will there be a bias current between the OPi's Vbus regulator and the externally fed hub supply voltage?

If you use an externally powered USB hub on your Orange Pi, please tell us your experience: What OPi model do you use, which USB hub model, are there any problems, is the OPi powered by the hub when the OPi's power supply is actually off/disconnected?

Thank you for sharing your experience!
Mark

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Post time 2016-6-4 01:22:15 | Show all posts
Edited by KY69 at 2016-6-3 14:26

Three of my OPi PCs are running with external HDDs connected to USB ports. One of them uses a 3.5" disk, so it has to be powered, but the other two are using 2.5" HDDs which I first tried to use without connecting them to external power sources. It did not work, so since the enclosures had the option to be connected to an external power supply that's what I did, and now they are all running 24/7 flawlessly. I noticed the few times I rebooted and shutdown restarted the ones connected to the smaller disks that even when the OPis were off they would still be partially powered by the USB port, for instance, if I disconnected the OPi's power supply but left the HDD connected to the USB port (and the HDD powered on), the standby LED on the disk enclosure would still be on (it goes off if the enclosure is powered but not connected to any USB port), and the disk would try to boot the OPi but unsucessfully.

I did not try to use a powered USB hub as you intend to, but I guess the end result as far as partially powering the OPis via a USB port would be the same, so now to sort of answering your question, there seems to be no problem so far. The OPis are running at around 50°C (ranging from the low 30's when untouched for a few hours to sometimes reaching the higher 60's when working with higher loads on the CPU, all in °C). The room temperature is around 20°C, and the OPis are on 24/7. I am using loboris images. This has been going on for a few months now, and there were no anomalies or strange behavior so far.

One more piece of information, the OPis are using each a dedicated 5V5A power supply, so that's why I believed they should be able to handle a 2.5" disk each at first, but I guess that there must be a current limit on the USB ports and that was not enough to properly power the external HDDs.

Empirically there seems to be no problem, in theory I'm sure this is not ideal. If anyone can contribute with a technical electrical explanation would be great.

OPi 2. OPi-PC, OPi+2E, OPi-PC2

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Post time 2020-1-7 16:09:49 | Show all posts
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