Powering Arduino Uno buy cutting a USB cable and soldering to USB socket at PCB

Hello all ,

Long time reader first time poster. I have a project which I have a Uno and a RPi communicating via i2c , I am using a portable mobile phone power bank to power both Arduino and RPi from USB/micro USB ports.

But I need to free up the USB port on the arduino to be able to connenct with my computer . I read it's not safe to connect 5v directly to arduino 5v pin.

Can I simply cut a USB wire from my power supply and solder red and black wires to USB socket at PCB (is this called back feeding) ? if I do that, do I have to make sure I use a USB cable with 5V disconnected for data transfer?

Thanks

"I read it's not safe to connect 5v directly to arduino 5v pin."

Baloney. Add a diode from 5V (anode) to Vin (cathode) so the regulator is not reverse driven. http://www.ti.com/lit/ds/symlink/lm1117-n.pdf See page 11.