PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 102

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

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
The THPP serially inputs all the path overhead (POH) bytes from the TPOH port. The POH bytes
must be input in the same order that they are transmitted (J1, B3, C2, G1, F2, H4, F3, K3 and
N1). TOHCLK is the generated output clock used to provide timing for the TPOH port.
TOHCLK is a nominal 20.736 MHz clock generated by gapping a 25.92 MHz clock. Sampling
TPOHRDY high with the rising edge of TOHCLK identifies the MSB of the first J1 byte.
TPOHEN port is used to validate the byte insertion on a byte per byte basis. When TPOHEN is
sampled high on the MSB of the serial byte, the serial byte is inserted. When TPOHEN is
sampled low on the MSB of the serial byte, the serial byte is discarded.
The THPP calculates the path BIP-8 error detection code on the transmit data stream. The path
BIP-8 byte is calculated on all the payload bytes. The path BIP-8 byte is based on a bit
interleaved parity calculation using even parity. The calculated BIP-8 error detection code is
inserted in the B3 byte of the following frame.
Since there are multiple sources for the same overhead byte, the POH bytes must be prioritized
according to Table 6 before being inserted into the data stream.
Table 6 Path Overhead Byte Source Priority
Byte
J1
B3
C2
G1
F2
H4
Z3
Z4
Z5
Highest
Priority
J1 pass through
(PAIS=1)
B3 pass through
(PAIS=1)
C2 pass through
(PAIS=1)
G1 pass through
(PAIS=1
IBER=1)
F2 pass through
(PAIS=1)
H4 pass through
(PAIS=1)
Z3 pass through
(PAIS=1)
Z4 pass through
(PAIS=1)
Z5 pass through
(PAIS=1)
OR
Path trace buffer
(PTBJ1=1)
C2 ind. reg.
(SRCC2=1)
PRDI[2:0] and
PREI[3:0]
(ENG1REC=1)
F2 ind. reg.
(SRCF2=1)
H4 pass through
XOR H4 ind.
reg.
(SRCH4=1
ENH4MASK=1)
Z3 ind. reg.
(SRCZ3=1)
Z4 ind. reg.
(SRCZ4=1)
Z5 ind. reg.
(SRCZ5=1)
AND
J1 ind. reg.
(SRCJ1=1)
G1 ind. reg.
H4 ind. reg.
(SRCH4=1)
(SRCG1=1)
S/UNI-2488 Telecom Standard Product Datasheet
Calculated B3
XOR TPOH
(TPOHEN=1
B3MASKEN=1)
H4 pass through
XOR TPOH
(TPOHEN=1
H4MASK=1)
AND
AND
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
TPOH
(TPOHEN=1)
Released
Lowest
Priority
J1 pass
through
Calculated
B3
XOR
B3MASK
C2 pass
through
G1 pass
through
F2 pass
through
H4 pass
through
Z3 pass
through
Z4 pass
through
Z5 pass
through
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