====== I2C interface using the GPIO pins ======
This page introduces how you can I2C interface using GPIO pins.\\
{{:en:u3:u3ioport_num.png?500|}}

**Note the GPIO-I2C support 1.8 Volt interface like other IO ports on Exynos processor.**\\
**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| |

<WRAP left round tip 100%>
If your ODROID-U3 have old version kernel you need to update using odroid-utility.
  sudo odroid-utility.sh
</WRAP>
First, You will update the apt-get to install i2c-tools on your **ODROID-U3**.
  sudo apt-get update
  sudo apt-get install i2c-tools
Then, You can see i2c devices with i2cdetec command.
  sudo modprobe i2c-dev
  sudo i2cdetect -l
To use GPIO-I2C you need to load i2c-gpio-custom device driver module.\\
Usage : i2c-gpio-custom bus[0..3]=I2CBUS,SDA,SCL
  sudo modprobe i2c-gpio-custom bus0=4,200,199
  sudo i2cdetect -l