ST2205U
8. CHIP-SELECT LOGIC (CSL)
TheꢀST2205Uꢀbuildsꢀinꢀoneꢀchipꢁselectꢀsignalꢀ(
)ꢀforꢀ
eachꢀexternalꢀchipꢁselect.ꢀChipꢁselectꢀsignalꢀ
ꢀ canꢀchangeꢀ
CS6
CS0
embeddedꢀ16KꢀbytesꢀmaskꢀROMꢀandꢀsixꢀchipꢁselectꢀsignalsꢀ
multiplexedꢀwithꢀPD5~0ꢀofꢀPortꢁDꢀwhichꢀareꢀusedꢀtoꢀselectꢀ
devicesꢀonꢀtheꢀexternalꢀbus.ꢀThereꢀareꢀtwoꢀoptionsꢀforꢀtheꢀfirstꢀ
16KꢀbytesꢀmemoryꢀwhichꢀareꢀcontrolledꢀbyꢀMMDꢀpin.ꢀTieꢀMMDꢀ
toꢀgroundꢀtoꢀselectꢀnormalꢀmodeꢀandꢀenableꢀinternalꢀROMꢀforꢀ
theꢀfirstꢀ16Kꢀbytesꢀmemory.ꢀConnectꢀMMDꢀtoꢀchipꢁselectꢀofꢀanꢀ
externalꢀdeviceꢀtoꢀselectꢀemulationꢀmodeꢀandꢀdisableꢀinternalꢀ
ROM.ꢀAfterꢀresetꢀcycles,ꢀMMDꢀchangesꢀtoꢀanꢀoutputꢀandꢀ
toꢀbeꢀaddressꢀsignalꢀA23ꢀtoꢀmakeꢀoneꢀsingleꢀdeviceꢀofꢀ16Mꢀ
bytesꢀatꢀ ꢀ possible.ꢀTheꢀaddressꢀrangeꢀofꢀ ꢀ ofꢀhigherꢀ
numberꢀfollowsꢀtheꢀrangeꢀofꢀpreviousꢀoneꢀofꢀlowerꢀnumber.ꢀ
ꢀ
CS5
CSx
Note:ꢀWriteꢀ“1”ꢀtoꢀbitꢀofꢀportꢀdirectionꢀcontrolꢀ
registerꢀPCD,ꢀthenꢀtoꢀbitꢀofꢀportꢀ
functionꢁselectꢀregisterꢀPFDꢀtoꢀactivateꢀtheꢀ
designatedꢀchipꢁselectꢀsignal.
outputsꢀchipꢁselectꢀsignalꢀ
.ꢀReferꢀtoꢀFIGUREꢀ8ꢁ1ꢀforꢀtwoꢀ
CS0
connectionsꢀofꢀdifferentꢀmodes.ꢀ
ꢀ
TwoꢀbitsꢀCSM[1:0]ꢀofꢀportꢀmiscellaneousꢀregisterꢀ(PMCR)ꢀ
selectꢀfourꢀmodesꢀofꢀCSLꢀwhichꢀdefineꢀtheꢀmemoryꢀsizeꢀofꢀ
ꢀ
ꢀ
A. Normal Mode
B. Emulation Mode
FIGURE 8-1 Connections Of MMD/
CS0
ꢀ
ꢀ
Versionꢀ1.0ꢀ
10/32ꢀ
ꢀ ꢀ 6/13/2007ꢀ
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
