BC9824 datasheet(8/22 Pages) HOLTEK

8 / 22 page

Rev. 1.00

October 20, 2015

BC9824

• Payload

Thepayloadistheuserdefinedcontentofthe

packet.Itcanbe0to32byteswide,anditis

transmittedon-airasitisuploaded(unmodified)to

thedevice.

TheBC9824providestwoalternativesforhandling

payloadlengths,staticanddynamicpayloadlength.

Thestaticpayloadlengthofeachofsixdatapipes

canbeindividuallyset.

Thedefaultalternativeisstaticpayloadlength.

Withstaticpayloadlengthallpacketsbetweena

transmitterandareceiverhavethesamelength.

StaticpayloadlengthissetbytheRX_PW_Px

registers.Thepayloadlengthonthetransmitter

sideissetbythenumberofbytesclockedintothe

TX_FIFOandmustequalthevalueintheRX_

PW_Pxregisteronthereceiverside.Eachpipehas

itsownpayloadlength.

DynamicPayloadLength(DPL)isanalternativeto

staticpayloadlength.DPLenablesthetransmitter

tosendpacketswithvariablepayloadlengthtothe

receiver.Thismeansforasystemwithdifferent

payloadlengthsitisnotnecessarytoscalethe

packetlengthtothelongestpayload.

WithDPLfeaturetheBC9824candecodethepay-

loadlengthofthereceivedpacketautomatically

insteadofusingtheRX_PW_Pxregisters.The

MCUcanreadthelengthofthereceivedpayload

byusingthecommand:R_RX_PL_WID.

InordertoenableDPLtheEN_DPLbitinthe

FEATUREregistermustbeset.InRXmodethe

DYNPDregisterhastobeset.APTXthattransmits

toaPRXwithDPLenabledmusthavetheDPL_P0

bitinDYNPDset.

• CRC

TheCRCistheerrordetectionmechanisminthe

packet.ThenumberofbytesintheCRCisset

bytheCRCObitintheCONFIGregister.Itmay

beeither1or2bytesandiscalculatedoverthe

address,PacketControlField,andPayload.

Thepolynomialfor1byteCRCisX8+X2+X+1.

Initialvalueis0xFF.

Thepolynomialfor2byteCRCisX16+X12+X5+

1.Initialvalueis0xFFFF.

NopacketisacceptedbyreceiversideiftheCRC

fails.

Packet Handling

BC9824usesburstmodeforpayloadtransmission

andreceive.

ThetransmitterfetchespayloadfromTXFIFO,au-

tomaticallyassemblesitintopacketandtransmits

thepacketinaveryshortburstperiodwith1Mbpsor

2Mbpsairdatarate.

Aftertransmission,ifthePTXpackethastheNO_

ACKflagset,BC9824setsTX_DSandgivesanactive

lowinterruptIRQtoMCU.IfthePTXisACKpacket,

thePTXneedsreceiveACKfromthePRXandthen

assertstheTX_DSIRQ.

Thereceiverautomaticallyvalidatesanddisassembles

receivedpacket,ifthereisavalidpacketwithinthe

newpayload,itwillwritethepayloadintoRXFIFO,

setRX_DRandgiveanactivelowinterruptIRQto

MCU.

Whenautoacknowledgeisenabled(EN_AA=1),the

PTXdevicewillautomaticallywaitforacknowledge

packetaftertransmission,andre-transmitoriginal

packetwiththedelayofARDuntilanacknowledge

packetisreceivedorthenumberofre-transmission

exceedsathresholdARC.Ifthelateronehappens,

BC9824willsetMAX_RTandgiveanactivelowin-

terruptIRQtoMCU.Twopacketlosscounters(ARC_

CNTandPLOS_CNT)areincrementedeachtime

apacketislost.TheARC_CNTcountsthenumber

ofretransmissionsforthecurrenttransaction.The

PLOS_CNTcountsthetotalnumberofretransmis-

sionssincethelastchannelchange.ARC_CNTis

resetbyinitiatinganewtransaction.PLOS_CNTis

resetbywritingtotheRF_CHregister.Itispossible

tousetheinformationintheOBSERVE_TXregister

tomakeanoverallassessmentofthechannelquality.

ThePTXdevicewillretransmitifitsRXFIFOisfull

butreceivedACKframehaspayload.

AsanalternativeforPTXdevicetoautoretransmitit

ispossibletomanuallysettheBC9824toretransmit

apacketanumberoftimes.Thisisdonebythe

REUSE_TX_PLcommand.

Whenautoacknowledgeisenabled,thePRXdevice

willautomaticallychecktheNO_ACKfieldinre-

ceivedpacket,andifNO_ACK=0,itwillautomati-

callysendanacknowledgepackettoPTXdevice.If

EN_ACK_PAYisset,andtheacknowledgepacket

canalsoincludependingpayloadinTXFIFO.

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