PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
individual channels. Setting RCAEN[0] enables addresses 0 through 7, and
RCAEN[3] enables addresses 24 through 30. This is typically used to allow more
than one slave device to share the Receive UTOPIA master bus. When polled,
the Receive Packet Available (RPA) output indicates whether there is at least one
cell available for transfer from the polled link. Upon selection, the interface
handles data pausing anywhere in the middle of a cell transfer.
In the 8- and 16-bit UTOPIA Level 2 Single Address mode, the S/UNI-IMA-8
operates as a single device with a single cell FIFO, with all cells being identified
by their virtual PHY ID (VPHY ID) in an address prepend. The address prepend
may be optionally mapped to the HEC/UDF field in order to maintain the standard
cell length. When the address presented on the Any-PHY/UTOPIA Interface
RADR pins matches a programmable 5-bit configuration register (DEVID), the
RXAPS will respond to polls. In all other cases, the output signals are tristated
which allows other slave devices to respond. When polled, the RPA output
indicates whether there is at least one cell available for transfer from any link.
In the 8- and 16-bit Any-PHY Slave mode, the S/UNI-IMA-8 operates as a single
device with a single cell FIFO, with all cells being identified by their virtual PHY ID
(VPHY ID) in a address prepend. When the address presented on the Any-
PHY/UTOPIA Interface RADR pins matches a programmable 5-bit configuration
register (DEVID), the RXAPS will respond to polls. In all other cases, the output
signals are tristated which allows other slave devices to respond. When polled,
the RPA output indicates whether there is at least one cell available for transfer
from any link. In Any-PHY mode, data pausing is not supported.
In all modes, an optional prepend is allowed on the bus. This prepend will
always be set to zero and has no significance to the S/UNI-IMA-8 but is provided
for interoperability.
To support current and future devices, the interface is configurable as either an
Any-PHY or UTOPIA L2 interface. Table 3 summarizes the distinctions between
the two protocols.
Table 3 UTOPIA L2 and Any-PHY Comparison
Attribute
UTOPIA L2
Any-PHY
Latency
RDAT[15:0], RPRTY, and
RDAT[15:0], RPRTY, RSOP
RSOP are driven or become and RSX are driven or
high impedance immediately become high impedance on
upon sampling RENB low or the RCLK rising edge
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
45
PMC [ PMC-SIERRA, INC ]
