User Guide

Figure4.S P IW riteCom m and
T heSi4455contains an internalM CU which controls alltheinternalfu nctions oftheradio.For
SPIread com m ands ,a typicalcom m u nication flow ofcheckingclear-to-s end(C T S)is u s ed to
m akes u retheinternalM C U has execu tedthecom m and andpreparedthedata to beou tpu t
ov ertheSDO pin.Figu re5 dem ons trates thegeneralflow ofan SPIread com m and.Oncethe
CT S v alu ereads FFh,then theread datais ready to beclocked ou t to thehos t M C U .T he
typical tim e for a v alid FFh C T S reading is 20 μ s . Figu re 6 dem ons trates the rem aining read
cycleafterCT S is s et to FFh.T heinternalM CU willclock ou t theSDO data on thenegativ e
edges o thehos t M CU s hou ld proces s theSDO data on theris ingedgeofSC L K .
Figure5.S P IR eadCom m and -CheckCT S Value
Figure6.S P IR eadCom m and-CheckO utR eadData