PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 559

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

14.5.3
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
TTOHEN
TOHCLK
TOHFP
Figure 46 TTOH and TOHFP Input Timing
Path Overhead Extraction
Figure 47 shows the receive path overhead (RPOH) functional timings. The RPOH port (RPOH,
RPOHEN and B3E) is used to output the POH bytes of the STS (VC) payloads and the path BIP-
8 errors. Note that the RPOH is only provided for the first STS-12. In OC-48c mode, all bytes of
interest are available. In cross connect mode, path and BIP-8 information from STS-12 #2-4 are
unavailable.
The POH bytes are output on RPOH MSB first in the same order that they are received. Since
ROHFP is synchronized on the transport frame, zero, one or two path overhead can be output per
path per frame. RPOHEN is used to indicate new POH bytes on RPOH. RPOHEN is either
asserted or de asserted for the nine POH bytes. The path BIP-8 errors are output on B3E at the
same time the path trace byte is output on RPOH. Optionally, block BIP-8 errors can be output on
B3E.
Figure 47 shows that RPOH and RPOHEN are aligned with the falling edge of ROHCLK. The
rising edge of ROHCLK should be used to sample RPOH and RPOHEN. Sampling ROHFP high
identifies the MSB of the path trace byte of STS-1/STM-0 #1 on RPOH and the first possible path
BIP-8 error of STS-1/STM-0 #1 on B3E.
TTOH
7
8
1
2
3
4
S/UNI-2488 Telecom Standard Product Datasheet
5
A1 #1
A1 #1
6
7
8
1
Released
2
559