Hi Charlie
The I2C, Valve Driver, SNES and DDS modules can only be powered by a compatible Bpod state machine. Currently, this only includes the pocket state machine prototype, but will include all subsequent state machine hardware, beginning with Bpod State Machine v1.0 to be released this fall.
How did you get your I2C module? FYI, we recently updated the board design, to include a critical bug fix. When powered by USB, an added diode prevents unnecessary current drain through the 5V regulator of the state machine power interface. I *strongly recommend updating to the new board if possible. If you purchased the board from our assembly service, we should have sent you an updated board in the mail. Please contact sales if you have not received it.
I2C1 should be a valid action, if the I2C module was detected by the state machine. Click the magnifying glass icon on the Bpod console, to see a list of recognized events and output actions. If the I2C module and its events are not visible, try clicking the "refresh" icon. If your Bpod console does not look like the one pictured, you need to update your software and firmware using the Gen2 repository.
-Josh