I'm using a Raspberry Pi Zero as a USB device, i.e. it is connected and powered via the OTG USB port to a USB host (in this case another Raspberry Pi, but it could be a PC or any other USB host):

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However with this setup I can't unplug the device without unpowering it. If instead I power the Raspberry Pi Zero with an external power source (via GPIO or via USB PWR IN) I can't also connect the USB host, because two discrete 5V power sources would power the Raspberry Pi Zero and this would be bad, I guess.

Question 1: how can I power my Raspberry Pi Zero from a power source, while being able to safely plug and unplug the USB OTG host?

Question 2: in the specific scenario with two Raspberries, if I power both boards with the same power supply (so the 5V would be already shared), would it be still bad to have power from USB OTG and USB PWR IN at the same time?

Question 3: what happens if I cut the VBUS conductor inside the OTG cable? The device board would still be detected by the host? The GND conductor has to be cut as well?

1 Answer 1


The proper way to do this would be to disconnect the positive supply wire in the USB cable, or USB port. The ground would still need to be connected in order for USB data transfer to occur.

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