User Guide

T ypicalA pplicationBlockDiagram
MCU
RF module
With
Antenna
NIRQ
SCLK
MISO
MOSI
NSEL
SDN
LDO
VDD
GND
IO
Serial Peripheral Interface
T heSi4455R F m odu lecom m u nicates with thehos t M C U ov era s tandard 4-wires erial
peripheralinterface(SPI):SC L K ,SD I,SDO,andnSE L .T heSPIinterfaceis des igned to
operateat a m axim u m of10M H z.T heSPItim ingparam eters arelis tedin T able1.T hehos t
M C U writes data ov ertheSD Ipin andcan read datafrom thedev iceon theSDO ou tpu t pin.
Figu re4s hows an SPIwritecom m and.T henSE L pin s hou ld go low to initiatetheSPI
com m and.T hefirs t byteofSDIdatawillbeoneoftheAPIcom m ands followed by n bytes of
param eterdatawhich willbev ariabledependingon thes pecificcom m and.T heris ingedges of
SCL K s hou ldbealigned with thecenteroftheSDIdata.
T able1.S erialInterfaceT im ingP aram eters