PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 560

• Manufacturer Part Number: PM5381-BI
• Description: ATM UNI, Single Channel ATM PHY Interface for 2488.32Mbps
• Manufacturer: PMC-Sierra, Inc.

14.5.4
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
B3E (B3EBLK=0)
B3E (B3EBLK=1)
Figure 47 RPOH Output Timing
Path Overhead Insertion
Figure 48 shows the transmit path overhead (TPOH) functional timings. The TPOH port (TPOH,
TPOHEN and TPOHRDY) is used to input the POH bytes of the STS (VC) payloads. Note that
the TPOH is only provided for the first STS-12. In OC-48c mode, all bytes of interest may be
inserted. In cross connect mode, path bytes from STS-12 #2-4 cannot be inserted in this manner.
The POH bytes are input on TPOH - MSB first - in the same order that they are to be transmited.
Since TOHFP is synchronized on the transport frame, zero, one or two path overhead can be input
per path per frame.
TPOHRDY is asserted to indicate that the S/UNI-2488 is ready to receive POH bytes. TPOHEN
is used to validate the insertion of the corresponding byte on TPOH. If TPOHRDY is logic high
and TPOHEN is sampled high on the MSB of the byte, the byte will be inserted in the path
overhead. When TPOHEN is sampled low on the MSB of the byte, the byte is not inserted in the
output stream. If TPOHRDY is logic low and TPOHEN is sample high on the MSB of the byte,
the byte will not be inserted in the path overhead and must be represented at the next opportunity.
TPOH and TPOHEN are sampled with the rising edge of TOHCLK. TPOHRDY is aligned with
the falling edge of TOHCLK. The rising edge of TOHCLK should be used to sample TPOHRDY.
Sampling TOHFP high identifies the MSB of the path trace byte of STS-1/STM-0 #1 on TPOH.
RPOHEN
ROHCLK
ROHFP
RPOH
8
J1
J1
8
8
B3
B3
8
S/UNI-2488 Telecom Standard Product Datasheet
... ...
8
Z4
Z4
8
Z5
Z5
8
J1
J1
Released
8
8
560