UDC

There is a USB client on handheld Vita devices. It uses a proprietary multi-connector on the OLED (PCH-1XXX) units and a micro-USB on the LCD (PCH-2XXX) units.

PCH-1XXX Pinout

Because of the existence of the USB ethernet adaptor, that means there exists a way to use the port in host mode probably through USB OTG or something similar.

Pin	Name	Description
1	Power?	No known use (N/C on cables, USB ethernet), goes to SN99057 pins 31-32
2	Power?	Same net as pin 1
3	Host detect?	GND on Vita and charger cable, connected to something on USB ethernet adapter
4	Digital audio out	To audio codec IC
5	Digital audio out	Same net as pin 4
6	UART RX	See UART Console
7	UART TX	See UART Console
8	UART CTS	See UART Console
9	UART RTS	See UART Console
10	Audio?	To audio codec IC
11	?Headset GND?	To Syscon (C11), connected on USB Ethernet
12	?Headset?	To Syscon (F9), connected on USB Ethernet
13	?	To Syscon (G4)
14	?GND?	GND on Vita and USB ethernet adapter, N/C on charging cable
15	?Peripheral Detect?	To large ceramic chip, 125K pull-down
16	GND	GND on Vita, N/C on USB ethernet and charging cable
17	VCC	+5V VDC
18	VCC	Same net as pin 17
19	GND	GND on Vita and charging cable, N/C on USB ethernet
20	D-	USB Data
21	D+	USB Data

PCH-2XXX Pinout

Port is a standard micro-USB Type B. Highly likely that USB OTG is supported in hardware although there's no evidence that it's enabled in software.

Pin	Name	Description
1	VCC	+5V VDC
2	D+	USB Data
3	D-	USB Data
4	ID	USB OTG
5	GND	Ground