Holtek BS82B12A-3 - Page 122

Rev. 1.20 122 January 23, 2015 Rev. 1.20 123 January 23, 2015
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
Bit2 TXBRK:Transmitbreakcharacter
0:Nobreakcharacteristransmitted
1:Breakcharacterstransmit
TheTXBRKbitistheTransmitBreakCharacterbit.Whenthisbitis"0",thereare
nobreakcharactersandtheTXpinoperatesnormally.Whenthebitis"1",thereare
transmitbreakcharactersandthetransmitterwillsendlogiczeros.Whenthisbitis
equalto"1",afterthebuffereddatahasbeentransmitted,thetransmitteroutputisheld
lowforaminimumofa13-bitlengthanduntiltheTXBRKbitisreset.
Bit1 RX8:Receivedatabit8for9-bitdatatransferformat(readonly)
Thisbitisonlyusedif9-bitdatatransfersareused,inwhichcasethisbitlocationwill
storethe9thbitofthereceiveddataknownasRX8.TheBNObitisusedtodetermine
whetherdatatransfersarein8-bitor9-bitformat.
Bit0 TX8:Transmitdatabit8for9-bitdatatransferformat(writeonly)
Thisbitisonlyusedif9-bitdatatransfersareused,inwhichcasethisbitlocation
willstorethe9thbitofthetransmitteddataknownasTX8.TheBNObitisusedto
determinewhetherdatatransfersarein8-bitor9-bitformat.
UCR2 register
TheUCR2registeristhesecondofthetwoUARTcontrolregistersandservesseveralpurposes.One
ofitsmainfunctionsistocontrolthebasicenable/disableoperationoftheUARTTransmitterand
ReceiveraswellasenablingthevariousUARTinterruptsources.Theregisteralsoservestocontrol
thebaudratespeed,receiverwake-upenableandtheaddressdetectenable.Furtherexplanationon
eachofthebitsisgivenbelow.
Bit 7 6 5 4 3 2 1 0
Name TXEN RXEN BRGH ADDEN WAKE RIE TIIE TEIE
R/W R/W R/W R/W R/W R/W R/W R/W R/W
POR 0 0 0 0 0 0 0 0
Bit7 TXEN:UARTTransmitterenabledcontrol
0:UARTtransmitterisdisabled
1:UARTtransmitterisenabled
ThebitnamedTXENistheTransmitterEnableBit.Whenthisbitisequalto"0",the
transmitterwillbedisabledwithanypendingdatatransmissionsbeingaborted.In
additionthebufferswillbereset.InthissituationtheTXpinwillbeusedasanI/Oor
otherpin-sharedfunctionalpin.
IftheTXENbitisequalto"1"andtheUARTENbitisalsoequalto"1",the
transmitterwillbeenabledandtheTXpinwillbecontrolledbytheUART.Clearing
theTXENbitduringatransmissionwillcausethedatatransmissiontobeabortedand
willresetthetransmitter.Ifthissituationoccurs,theTXpinwillbeusedasanI/Oor
otherpin-sharedfunctionalpin.
Bit6 RXEN:UARTReceiverenabledcontrol
0:UARTreceiverisdisabled
1:UARTreceiverisenabled
ThebitnamedRXENistheReceiverEnableBit.Whenthisbitisequalto"0",the
receiverwillbedisabledwithanypendingdatareceptionsbeingaborted.Inaddition
thereceivebufferswillbereset.InthissituationtheRXpinwillbeusedasanI/Oor
otherpin-sharedfunctionalpin.IftheRXENbitisequalto"1"andtheUARTENbit
isalsoequalto"1",thereceiverwillbeenabledandtheRXpinwillbecontrolledby
theUART.ClearingtheRXENbitduringareceptionwillcausethedatareceptionto
beabortedandwillresetthereceiver.Ifthissituationoccurs,theRXpinwillbeused
asanI/Oorotherpin-sharedfunctionalpin.