If a USB Cable is being used between two devices, are the power wires needed

datapowerusb

I am trying to figure out a way to give power to an android tablet and a DSLR camera at the same time (for a photo booth).

I was able to purchase an AC adaptor "battery" plugin for the camera, but the DSLR needs to be plugged in to the tablet via an OTG data cable (USB).

My question is; Can I open the USB cable and cut the two power cables (red and black), then wire them to a mobile device wall wart charger?

Basically, I want to open the USB cord and not cut the data cables so that the camera and tablet are still connected via data, but I want to remove the red and black wires going to the camera (so the camera does not get power). Instead, I want the power wires going from the tablet to go to AC power via a mobile device wall wart charger.
will this ruin any data transfer? Does the data need to be transferred with the power for information to be sent?

I think I've over-explained enough, but please ask if I haven't made sense.

Best Answer

Yes the power and ground lines are needed. The ground line is needed because the OTG feature works by grounding the ID pin the the USB plug. If the ID pin is left floating then the object configures as a device. If the pin is grounded then the object configures as a host. The power line is needed because most if not all devices use the presence of power as a trigger to initiate USB enumeration. If no power is present then the object will not check the data lines to see if something is present.

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