Use the HDMI breakout beard and plug in the Headless Ghost.

Follow the pinout described in the datasheet of the headless ghost for correct wiring.

• Breakout Pin 15 ---SCL--> Pin 2 (BCM) or Pin 3 (Standard) RPi
• Breakout Pin 16 ---SDA--> Pin 3 (BCM) or Pin 5 (Standard) RPi
• Breakout Pin 17 ---GND--> GND RPi
• Breakout Pin 18 ---3.3V--> 3.3V RPi

Be careful with pull-up resistors and voltage!!!

I can directly attach my adapter to the Pi because:

1. the E²PROM supports input voltages from 1.7V up to 5.5V (depending on I²C frequency)
2. every Raspberry Pi from Model B+ on has internal pull-up resistors to 3.3V

Therefore I can operate at 3.3V which is the voltage level the I²C lines are already pulled up to internally.

For use with different microcontrollers or E²PROM use level shifters.