I'm trying to develop my own OS kernel from scratch for the raspberry pi and I want to be able to debug my code from my computer over putty through a cable. Now I've did a little googling and found out that everybody is using a special cable with a microcontroller on it that does what I'm trying to do but connects to the reasberry Pi's gpio pins instead of its USB port. I was told by someone that the hardware needed to communicate between the RPI and a standard PC already exists on the on the RPI and that I should be able to connect my RPI directly through USB port to my computer's USB port without a special cable containing additional hardware on it and without any Linux USB drivers. Is this true and how do I go about doing this. To clarify I want to get a UART console from rasberry pi over standard USB cable without any OS or drivers installed on the PI.