Turn your device into an I2C/SMBus terminal. The app allows you to interface with an MCP2221 and easily communicate with I2C/SMBus slaves.
You can also control the MCP2221's pin functions and make use of the on board ADC, Clock Out, DAC and GPIO.
In addition to this, the MCP2221's serial port connection is also controllable from the Serial Terminal part of the app.
The source code for this app can be downloaded from the MCP2221 page: