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RELEASED
PM73122 AAL1GATOR-32
DATASHEET
PMC-1981419
ISSUE 7
32 LINK CES/DBCES AAL1 SAR PROCESSOR
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
65
In master mode, the SNK_INTF block receives RATM_D, RATM_PAR,
RATM_SOC, and RATM_CLAV while driving RATM_ENB. Once the UI is
enabled in this mode, and, if the RATM_CLAV input signal is asserted, the
SNK_INTF block waits for an RATM_SOC signal from the PHY layer. Once the
RATM_SOC signal arrives, the cell is accepted as soon as possible. The Start-
Of-Cell (SOC) indication is received coincident with the first word (only 8-bit
mode is supported) of each cell that is received on RATM_D. An 8 cell FIFO
allows the interface to accept data at the maximum rate. If the FIFO fills, the
RATM_ENB signal will not be asserted again until the device is ready to accept
an entire cell. The RATM_ENB signal depends only on the cell space and is
independent of the state of the RATM_CLAV signal. The RATM_CLAV signal
indicates whether the target device has a cell to send or not. Only cell level
handshaking is supported.
In PHY mode, the SNK_INTF block receives TPHY_D[15:0], TPHY_SOC, and
TPHY_ENB while driving TPHY_CLAV. The cell available (TPHY_CLAV) signal
indicates when the device is ready to receive a complete cell. In UTOPIA Level
One mode, TPHY_CLAV is always driven.
In UTOPIA Level Two mode, SNK_INTF normally responds as a single address
device. However there may be situations in some systems where groups of cells
targetted to a given A1SP may be clumped together. If one of the 8-cell A1SP
FIFO fills up so that it backs up into the 8-cell sink UTOPIA FIFO then a head-of-
line blocking problem can exist. To alleviate such a situation, the sink direction
can be configured as four separate addresses, where the bottom two bits of the
address indicate which A1SP is targeted to receive the cell. When polling any of
the A1SP addresses, a full indication will be given when the A1SP FIFO
associated with that address, reaches a 3/4 full state (room for 2 more cells) or
the UI cell sink FIFO already has two cells for that address. This will always
allow room for any cells that may still be queued in the sink UTOPIA FIFO and
prevent head-of-line blocking. Full indications will be given for a specific port
until both full conditions are cleared.
When responding as a single address, TPHY_CLAV is driven the cycle following
ones in which TPHY_ADDR(4:0) matches CFG_ADDR(4:0) in
UI_SNK_ADD_CFG register. When responding as 4 addresses, TPHY_CLAV is
driven the cycle following ones in which TPHY_ADDR(4:2) matches
CFG_ADDR(4:2) in UI_SNK_ADD_CFG register. Otherwise TPHY_CLAV is tri-
stated. If, in addition to an address match, during the previous cycle TPHY_ENB
was high and it is low in the current cycle, then the device is selected and the
SRC_INTF begins accepting the cell that is being received.
The SNK_INTF block waits for an SOC. When an SOC signal arrives, a counter
is started, and 53 bytes are received. If a new SOC occurs within a cell, the
counter reinitializes. This means that the corrupted cell will be dropped and the