====== UART interface using the IO-Port #1 ======
This page introduces how you can UART Interface using the IO-Port #1\\

{{:en:u3:u3ioport_num.png?500|}}

**J4 - 2x4 pins(IO Port #1)**
^ Pin Number ^ Expansion Net Name ^ Export Number ^ Pin Number ^ Expansion Net Name ^ Export Number ^
|1|XEINT_8 (GPX1.0)| #199 |2|1.8V Power| |
|3|XEINT_9 (GPX1.1)| #200 |4|XURXD_0 (UART_0_RXD)| /dev/ttySAC0 | 
|5|XEINT_13 (GPX1.5)| #204 |6|XUTXD_0 (UART_0_TXD)| /dev/ttySAC0 |
|7|Ground| |8|5V0 Power| |

=== How to test your UART0 of IO-Port #1 ===

You need to prepare below items.\\
  * **ODROID-U3**
  * USB-UART Module Kit
  * jumper wire x4
  * serial comunication utility on your Host PC

1. You will connect jumper wire to IO-Port #1.\\
This picture is that jumper is connected.\\

{{:en:u3:u3ioport_wire_connected.jpg?500|}}

**IO-PORT UART Block Diagram**

{{:en:u3:u3ioport_wire.png?500|}}

2. HOST PC setup.\\
You will open USB Module Devices on your HOST PC.\\
**Ubuntu**\\
Install Serial comunication utility.
  sudo apt-get install minicom
After check your usb serial node, Open serial port.
  ls /dev/ttyUSB*
  sudo minicom -b 115200 -D /dev/ttyUSB0


3. Target board(**ODROID-U3**) setup.\\
Set a serial node on your **ODROID-U3**
  stty -F /dev/ttySAC0 115200
  
4. **ODROID-U3** -> HOST PC test.\\
**ODROID-U3**
  echo 1 > /dev/ttySAC0

5. HOST PC -> **ODROID-U3** test.\\
**ODROID-U3**\\
  cat /dev/ttySAC0
HOST PC\\
Send characters via minicom.