S/UNI®-JET Data Sheet
Released
Figure 74 Multi-PHY Polling and Addressing Receive Cell Interface
RFCLK
RCALEVEL0=0
DRCA[D]
CA(A)
CA(B)
CA(C)
CA(B)
CA(D)
X
RCA
RENB
A
1Fh
B
1Fh
C
1Fh
X
B
1Fh
D
1Fh
E
RADR[2:0]
RSOC
(n-7)
(n-6)
(n-5)
(n-4)
(n-3)
(n-2)
(n-1)
(n)
W
W
W
W
W
W
W
W
W1
W2 W3
RDAT[15:0]
RPRTY
Figure 74 shows an example of the multi-PHY polling and selection sequence supported by the
S/UNI-JET . "A", "B", "C", "D", and "E" represent any arbitrary address values which may be
occupied by the S/UNI-JET . Initially cell data is being received from PHY “D,” and the
DRCA[D] signal shows how the DRCA[x] signals behave based on the value of the
RCALEVEL0 register bit(s). The ATM Layer device is not restricted in its polling order. The
PHY associated with address "A" indicates it does not have a cell available, but PHY "B"
indicates that it does. As a result, the ATM Layer places address "B" on RADR[2:0] the cycle
before RENB is asserted to select PHY "B" as the next cell source. In this example, PHY "C"s
status is ignored. The ATM Layer device is not constrained to select the latest PHY polled. As
soon as the cell transfer is started, the polling process may be restarted. The data on RDAT (W1,
W2, ..) may be 8-bit or 16-bits wide, depending on the setting of the ATM8 input.
During multi-PHY operation, several PHY layer devices share the RDAT[15:0], RSOC, RPRTY,
and RCA signals. As a result, these signals must be tri-stated in all PHY devices which have not
been selected for reading or polling by the ATM Layer. Selection of which PHY layer device is
being read is made by the value on RADR[2:0] the cycle before RENB is asserted and affects the
RDAT[15:0], RSOC, and RPRTY signals. The value of RADR[2:0] selects the PHY being polled
for the RCA signal, and all devices not corresponding to this address must tri-state its RCA
output. These multi-PHY operations are directly supported by the S/UNI-JET.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
318
PMC [ PMC-SIERRA, INC ]
