Unlike the 'A' series, on the s3is it is not obvious where the memory-mapped hardware register that the USB V+ is connected to is located.
If you use software functions to detect USB change-of-state, there can be an enormous 40 to 72 msec delay before the change is detected !
Function '_kbd_read_keys_r2' seems to look at locations 0xC000001C and C0000024.
Has anyone studied this ?
How can I monitor the USB connection directly at the hardware register ?