External I2C bus / NFC

Connector pinout

Pin	Signal	Voltage
1	VCC	+5.0V
2	I2C SCL	+3.3V
3	I2C SDA	+3.3V
4	NFC IO	+3.3V
5	GND	GND

RDDRONE-FMUK66 Rev. C schematic

RDDRONE-FMUK66 Rev. B schematic

Rev. B (and older boards) are not supported anymore. This information is left for reference.