STLC1510 datasheet(35/40 Pages) STMICROELECTRONICS

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STLC1510

The TxBP pin is not part of the Utopia Level 2 speci-

fication, but its functionality does not interfere with

the operation of the Utopia Level 2 Interface. It can be

left unconnected if necessary for a given application.

This signal is described in more detail in the NIF

chapter of this document.

Features of MPHY Layer Cell-Level Handshake (Rx

Direction):

A single MPHY port at a time is selected for a

cell transmission. However, another MPHY port

may be polled for its RxClav status while the

selected MPHY port transfers data. The ATM

layer polls the RxClav status of a MPHY port by

placing its address on RxAddr. The MPHY port

(STLC1510 device) drives RxClav during each

cycle following one with its address on the

RxAddr lines.

The ATM selects an MPHY port for transfer by

placing the desired MPHY port address onto

RxAddr, when RxEnb is deasserted (high)

during the current clock cycle and asserted

(low) during the following clock cycle. All MPHY

devices examine the value on RxAddr for

selection purposes when RxEnb is deasserted

(high). The MPHY port is selected starting from

the cycle after its address is on the RxAddr

lines, and RxEnb is deasserted (low); and

ending in the cycle a new MPHY port is

addressed for selection, and RxEnb is

deasserted (high).

Figure 24. illustrates the timing diagram of the re-

ceive interface when a cell is received from PHY N

and the other PHYs are polled.

Figure 24. UTOPIA Level 2 receive timing, polling phase and selection phase.

Rx C lk

Rx E nb

URx Data

Rx Clav

Rx S O C

N-1

P4 0

P41

P42

P4 3

P4 4

P4 5

P4 6

P4 7

P4 8

H 1H2H3

N+1

N+ 3

N+ 1

N+ 3

N-1

N+3

N+1

NN +3

N+1

Rx A d dr

PH Y N

PH Y N + 3

polling

pollin g

C ell tr an sm iss io n fr om :

se le c tio n

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