XRT74L73 Datasheet, PDF (173/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
FIGURE 45. FLOW-CHART OF THE “UNI DEVICE SELECTION AND READ PROCEDURE” FOR THE MULTI-PHY OPERATION.
START
Poll all UNIs within the “Multi-PHY” System
Determine which UNIs contain ATM cell data
that need to be read
Select “Availble” UNI
1. Apply Utopia Address of the “selected” Receive
Utopia Interface block onto the “Utopia Address”
bus
2. Negate the RxEnB* signal
Begin reading ATM cell data into “Selected” UNI
1. Assert RxEnB*
2. Read in the first byte/word of ATM cell from the
“Receive Utopia Data Bus & check for the asserted
RxSoC signal
Continue to read in ATM Cell data
Is
RxClav
No
“High”
?
Yes
Wait for RxClav to toggle “high”
Does
No
the ATM
Layer processor Yes
wish to read more
cells from the
“selected”
Is
RxClav
“High”
?
No
UNI?
Yes
Check the RxClav level while reading
in the last byte (word) of the current cell..
Figure 46 presents a timing diagram that illustrates the
behavior of various “Receive UTOPIA Interface block”
signals, during the “Multi-PHY” UNI Device Selection
and Read operation.
FIGURE 46. TIMING DIAGRAM OF THE RECEIVE UTOPIA DATA AND ADDRESS BUS SIGNALS, DURING THE “MULTI-PHY”
UNI DEVICE SELECTION AND WRITE OPERATIONS.
1
2
3
4
5
6
7
8
9
10
11
12
RxUClk
RxUAddr[4:0] _{01h 1Fh 03h 1Fh}
RxUClav
RxUEn
01h
03h
Cell Received from 03h
RxUData [15:0] _{W23 W24 W25 W26}
RxUSoC
01h 03h 1Fh 01h 03h 1Fh
01h
03h
01h
03h
Cell Received from 01h
W0
W1
W2
W3
W4
03h 01h
03h
W5
W6
Note: regarding Figure 46
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