Patrick, I know that there are some issues… And the for now no documentation is available… But I have also good news, today I have finished the software (bitbanged) I2C interface, it uses the USART TX/RX pins for communication
The GPIO user application automatically identifies the attached device and display some report including decoded variables from sensors, so far these devices are supported:
DS1820 - oneWire temperature sensor
DHT11 - humidity & temperature sensor
BMP085 - I2C barometric sensor (temperature & pressure)