Specifications

1
I2C port
The RAK4270 exposes a I2C port, in which the SDA line is assigned to the pin9, and
SCL line is assigned to pin10. This I2C port allows to control additional slave sensors
with the RAK4270 using I2C protocol. The RAK4270 will be the master. If the I2C port
is used, then external pull-up resistors mus added to the SDA and SCL lines. The
recommended value of the resistors are 10 kOhm.
RF port
The RAK4270 module expose two types of RF antenna: IPEX and PAD. The most
straightforward way is to use the IPEX antenna port. In such case, you just to connect
the antenna to the IPEX connector on the module directly. In the other hand, for
specific needs, customers can design a PCB trace antenna, Chip antenna, SMA
antenna, or spring type antenna. In the latter case, the customer should use the PAD
type antenna port expose by this module. The external antenna should be matched to
the 50 Ohm RF transmission line.
VDD power in
It is recommended to add 4 decoupling capacitors near the module at the entrance of
the power supply pin. The recommended values of the capacitor are C1 =10uF,
C2=10uF, C3=100nF, C4=100nF.