PM7344 S/UNI-MPH
DATA SHEET
PMC-950449
ISSUE 6
MULTI-PHY USER NETWORK INTERFACE
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].
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
60
PMC [ PMC-SIERRA, INC ]
