Data Sheet

FSC‐BT646Datasheet
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 ShenzhenFeasycomTechnologyCo.,Ltd   www.feasycom.com
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4.6SerialInterfaces
4.6.1UART
FSC‐BT646provides onechannelsof UniversalAsynchronous Receiver/Transmitters(UART)(Full‐duplexasynchronous
communications).TheUARTControllerperformsaserial‐to‐parallelconversionondatareceivedfromtheperipheraland
aparallel‐to‐serialconversionondatatransmittedfromtheCPU. 
ThisisastandardUARTinterfaceforcommunicatingwithotherserialdevices.TheUART interfaceprovidesa simple
mechanismforcommunicatingwithotherserialdevicesusingtheRS232protocol.
Whenthemoduleisconnectedtoanotherdigitaldevice,UART_RXandUART_TXtransferdatabetweenthetwodevices.
Theremainingtwosignals,UART_CTSandUART_RTS,canbeusedtoimplementRS232hardwareflowcontrolwhere
bothareactivelowindicators.
Thismoduleoutputisat3.3VCMOSlogiclevels(tracksVCC).LevelconversionmustbeaddedtointerfacewithanRS‐
232levelcompliantinterface.
SomeserialimplementationslinkCTSandRTStoremovetheneedforhandshaking.WedonotrecommendlinkingCTS
andRTSexceptfortestingandprototyping.IfthesepinsarelinkedandthehostsendsdatawhentheFSC‐BT646deasserts
itsRTSsignal,thereissignificantriskthatinternalreceivebufferswilloverflow,whichcouldleadtoaninternalprocessor
crash.Thisdropstheconnectionandmayrequireapowercycletoresetthemodule.Werecommendthatyouadhere
tothecorrectCTS/RTShandshakingprotocolforproperoperation.
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Table3:PossibleUARTSettings
Parameter PossibleValues
Baudrate
Minimum 1200baud(≤2%Error)
Standard 115200bps(≤1%Error)
Maximum 921600bps(≤1%Error)
Flowcontrol  RTS/CTS,orNone
Parity  None,OddorEven
Numberofstopbits  1/1.5/2
Bitsperchannel  5/6/7/8
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Whenconnectingthemoduletoahost,pleasemakesuretofollow.
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Figure4:UARTConnection
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