I have a MultiWii Flight Control Board with a 4 pin connector marked J2 (pin 1-GND, pin 2-3.3V, pin 3-SCL, pin 4-SDA). My GPS module has a 4 pin connector marked (pin 1-GND, pin 2-RXD, pin 3-TXD, pin 4 VCC). What pin goes to what between the 2 modules for power and communications?