PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
Word Bits Parameter
Description
23:16 ICP offset or TC IMA mode: this field is indexed by the Physical
mode VPHY
address
Link tag and is used to determine the cell count
within a frame at which an ICP is to be inserted
for the link. The width of the field used by the
TIMA is dependent on the value of M used for the
particular group and is shown in the following:
M=256 ICP offset determined by bits [7:0]
M=128 ICP offset determined by bits [7:1]
M=64 ICP offset determined by bits [7:2]
M=32 ICP offset determined by bits [7:3]
The mapping of the ICP offset is set such that the
offset should not have to be changed if M is
changed. This field is read by the transmit
engine and is maintained by the PM. Values 0 to
255 are valid.
TC mode: this field is indexed by the TC tag
delivered by the IDCC and is used to determine
the VPHY ATM source FIFO associated with the
TC connection. This field is read by the TIMA and
is maintained by the PM. Only values 0 to 7 are
valid.
15:9
8:6
Reserved
Startup Cell
Count
Cell count used to track the first four cells after
startup sent into each link FIFO. Used to assert a
read inhibit signal per link
(TL_FIFO_READ_INHIBIT) until four cells have
been written into the link FIFO so that the
nominal 4 to 5 cell depth can be achieved. This
field must be initialized to 4 by the PM before the
link is enabled to ensure proper startup.
However, if the link is to be used for either a low
speed or high speed TC mode connection, this
field must be initialized to a value of 0 to prevent
any read inhibit. Maintained and used by TIMA.
5:0
Reserved.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
249
PMC [ PMC-SIERRA, INC ]
