User's Manual

M2SD50NBT
Datasheet
 7

4 BLUETOOTHFUNCTIONALDESCRIPTION
TheM2SD50NBTBluetooth(BT)blockisbasedontheCSR8811A08anddescribedintheTable2.
Table2:Bluetoothfunctions
Feature Description
HCI‐UARTInterface
TheUARTInterfaceisastandardhigh‐speedUARTinterface.Itoperatesupto4Mbps,
supportingBluetoothHCIUARTinterface.
PCMorI2SInterface
 ContinuousPCMencodedaudiodatatransmission andreceptionoverBluetooth
 Processoroverheadreductionth roughhardwaresupportforcontinual
transmissionandreceptionofPCMdata
 Abi‐directionaldigitalaudiointerfacethatroutesdirectlyintothebasebandlayer
ofthefirmware.ItdoesnotpassthroughtheHCIprotocollayer
 HardwareonCSR8811forsendingdatatoandfromaSCOconnection
 UptothreeSCOconnectionsonthePCMinterfaceatanyonetime
 PCMinterfacemaster,generatingPCM_SYNCandPCM_CLK
 PCMinterfaceslave,acceptingexternallygeneratedPCM_SYNCandPCM_CLK.
 Variousclockformatsincluding:
– *LongFrameSync
– *ShortFrameSync
 GCItimingenvironments
 13‐bitor16‐bitlinear,8‐bitμ‐laworA‐lawcompandedsampleformats
 Receivesandtransmitsonanyselectionofthreeofthefirstfourslotsfollowing
PCM_SYNC
 ThePC Mconfiguration optionsareenabledbysettingSKEY_PCM_CONFIG32 
CPUandMemory
 Usesa16‐bitRISCMCUforlowpowerconsumptionandefficientuseofmemory.
TheMCU,interruptcontroller,andeventtimerruntheBluetoothsoftwarestack
andcontroltheBluetoothradioandhostinterfaces.
 56KBofon‐chipRAMisprovidedtosupportthe
RISCMCUandissharedbetween
theringbuffersusedtoholdvoice/dataforeachactiveconnectionandthe
general‐purposememoryrequiredbytheBluetoothstack.
 5MbofInternalROMmemoryisavailableontheCSR8811.Thismemoryis
providedforsystemfirmware,storingCSR8811settingsand
programcode.
Build‐inStandard
WLANCoexistence
TheM2SD50NBTint e rnallysupportsthestandardWLANcoexistenceinterface
throughtheWLAN_ACTIVE,BT_PRIORITY,andBT_ACTIVEpins.
ReferenceClock
TheBTblockisconfiguredfor26MHzreferenceclockfrequency.Theclocksourceis
providedtoBTinternallyfromtheWLANblockondemandfromBT_CLK_REQ.
Note: TheWLANblockmustbeinitializedpriorbeforeBTclocksharingisenabled.
BTLowEnergy
SupportsLowEnergyspecificationwhichallowsforconnectionstodeviceswithsingle
modeLEfunction(suchasawatch,sensor,andHID).Theimplementationisoptimized
forcoexistencewithWLAN .
BT_RFKILL
TheNGFFpin‐54isconnectedto(BT_PWD_L)resetsandpowersdowntheBTblock.
Holdingthepin‐54atLowstateturnsofftheentireBTblock;allstateinformationis
lost.Toensureafullreset,theresetsignalsh ouldbeassertedforaperiodgreater
thanfive
milliseconds.