Expansion connectors
VCC (3.0V, max 100mA)
GND
VCOM (unregulated VBAT or VUSB, max 1A)
VUSB (both for input and output)
I2C (400kHz)
SPI
2 x UART
4 x GPIO/CS for SPI
1-wire bus for expansion identification
2 x GPIO connected to nRF51
ECCN/HTS
