XRT74L73 Datasheet, PDF (256/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
FIGURE 93. FLOW CHART DEPICTING THE FUNCTIONALITY OF THE LAPD RECEIVER
SSTTAARRTT
ENABLE THE LAPD RECEIVER
This is done by writing the value “0xFC into the
RxLAPD Control Register (Address = 0x18)
LAPD Receiver begins reading in the DL bits
from each inbound DS3 frame
DDooeses
thteheLLAAPPDD
RReceecievievrerddeteetcetct66
NO
cocnosnesceuctuitvieve
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11
YES
AABBOORRTTSSeqequuenencece
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ththeeLLAAPPDD
RReceecievivererddeteetcetct77
cocnonsesceucutitvivee
ZZereorsos
YES
??
NO
FFlalgagSSeqequuenencece
LLAAPPDDRReceecievivererisisreraedadininggininaaLLAAPPDD
MMesessasgaegeFFrarmame,ec, ocnotnatianiinnigngaaPPMMDDLL
MMesessasgage.e.
DDooeses
NO
ththeeLLAAPPDD
RReceecievivererdedteetcetct66
cocnosnesceuctuitvieve
ZZereoros _s
??
YES
EEnnddofofMMesessasgagee(E(EOOMM) ₎
VVEERRIFIFYYTTHHEEFFCCSSVVAALLUUEE
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SStattautsusRRegeigsitsetre.r...
“U“Un-ns-tsutfufffcocnotnetnetnstsoof _{fRReceecieviveded}
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InItnetrerrurputp”t”
DDooeses
ththeeLLAAPPDD
YES
RReceecievivererddeteetcetct77
cocnonsesceucutitvivee
ZZereorsos
??
NO
WWrirtieteRReceecievivededPPMMDDLLMMesessasgaege
inintotoththeeRReceecievieveLLAAPPDDMMesessasgagee
BBuufffefrer(A(Adddrdersessesses0x0DxDEE- _{-0x01x3153)5)}
EExxeceucuteteRReceecieviveeLLAAPPDD
InIntetrerrurputptSSerevrivcieceRRouotuitniene
11
NOTES:
1. The white (e.g., unshaded) boxes reflect tasks that
the user’s system must perform in order to config-
ure the LAPD Receiver to receive LAPD Mes-
sages.
2. A brief description of the steps that must exist
within the Receive LAPD Interrupt Service routine
exists in Section 4.3.6
4.3.4 The Receive Overhead Data Output Inter-
face
Figure 94 presents a simple illustration of the Re-
ceive Overhead Data Output Interface block within
the XRT74L73.
257