PM7344 datasheet(76/293 Pages) PMC

76 / 293 page

PM7344 S/UNI-MPH

DATA SHEET

PMC-950449

ISSUE 6

MULTI-PHY USER NETWORK INTERFACE

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

In general, the management functions include emptying cells from the transmit

FIFO, indicating when the transmit FIFO is full, maintaining the transmit FIFO

read and write pointers and detecting a FIFO overrun condition.

A Saturn Compatible Interface (SCI-PHYTM) FIFO is provided. This synchronous

FIFO accepts a write clock (TFCLK), a start of cell indication (TSOC), and a

write enable signal from the MPHY block. The interface provides a transmit cell

available status (TCA) which can transition from available to unavailable when

the transmit FIFO is near full and can accept no more than 4 writes (when

TFULL4 is logic 1) or when the FIFO is full and can accept no more writes

(default).

The TXFF indicates FIFO overruns using a maskable interrupt and register bits.

Writes to the TXFF while the FIFO is full (i.e. overruns) are ignored.

9.20

Saturn Compatible Multi-PHY Interface (MPHY)

The Saturn Compatible Multi-PHY Interface block (MPHY) permits the four

receive cell FIFOs (RXFF) and the four transmit cell FIFOs (TXFF) to share a

single cell interface on the S/UNI-MPH.

Two interface modes are supported: 1) multi-phy addressing (when the MPHEN

input is high) and 2) direct phy selection (when the MPHEN input is low).

When multi-phy addressing is enabled, one of four possible transmit/receive

FIFOs is selected by the TWA[1:0]/RRA[1:0] address signals respectively. The

cell available signal for each of the four transmit/receive FIFOs is also selected

by TWA[1:0]/RRA[1:0]. While a cell transfer is in progress to/from a particular

FIFO, the cell available indications from the remaining three FIFOs may be

polled using TWA[1:0] or RRA[1:0]. These indications are available on RCAMPH

(for the three remaining RXFFs) and on TCAMPH (for the three remaining

TXFFs). The cell available indication from the active FIFO is only valid at the

end of the cell transfer (or four reads/writes before the end of the cell transfer

depending on the configuration of the FIFO). The cell available indications are

also directly available on TCA[4:1] and RCA[4:1] when the multi-phy addressing

mode is enabled.

When direct phy selection is enabled, one of four possible transmit/receive

FIFOs is selected by the corresponding TWRENB[4:1]/RRDENB[4:1] signal

respectively. The cell available status for each of the transmit and receive FIFOs

is directly available on RCA[4:1] and TCA[4:1].

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