Can I plug USB data lines directly from slave device to the Omega2?



  • I am looking at using the USB_DM and USB_DP (along with 5v & ground) to connect to a web cam.

    After seeing https://community.onion.io/topic/2284/my-omega-2-2-dock-new/19 I realized that I might have voltage mismatch issue...the 3.3v Omega2 and the 5v webcam. Am I wrong about this?

    Am I going to damage the Omega2 if I do this?



  • Yep. You certainly can connect D+ and D- directly to slave USB device. However, you still have to power slave device with +5v ( according to USB standard). So there are 2 options: a) power with step-up converter b) power with external +5v power supply.



  • @Kris-Kelvin Awesome, thanks for the good news.

    What I'm doing, is taking a female micro-usb cable (cutting the end off of a micro-usb extension cable) for incoming power from a regular phone charger, running the 5v through the LD1117 as suggested in the omega2 docs. I was then intending to also run the 5v to another female end, this time of a USBA extension cable (also snipped off), and then plugging a USB camera and other devices into that. But I got worried about the voltage mismatch, thinking that the USB slave device might send back the full 5v. (Some things I read talked about 5V is actually more than intended, so that the voltage drop from the wire length could be absorbed.



  • @Allnight said in Can I plug USB data lines directly from slave device to the Omega2?:

    But I got worried about the voltage mismatch, thinking that the USB slave device might send back the full 5v. (Some things I read talked about 5V is actually more than intended, so that the voltage drop from the wire length could be absorbed.

    Only if it is improperly implemented or you allow the signal lines to connect before the ground, something USB connectors are physically designed to avoid, but that could conceivably happen with other custom wiring schemes.

    USB uses 5v power, but the signalling is 3.3v, or lower.


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