S/UNI®-JET Data Sheet
Released
Figure 56 Transmit PLCP Overhead
TPOHFP
F1
B1
octet
G1
M2
M1
Z2
Z1
octet
octet
octet
octet
octet
octet
TPOHCLK
TPOHCLK
TPOH
B
8
B
1
B B B B B B B
2 3 4 5 6 7 8
B
1
Don't Care
B1 Octet
F1 Octet
TPOHFP
TPOHINS
The Transmit PLCP Overhead diagram (Figure 56) shows the insertion of the PLCP path
overhead bits using the TPOH input, along with overhead clock (TPOHCLK), and PLCP frame
position indicator (TPOHFP). The path overhead octets are shifted in order with the most
significant bit (bit 1) of each octet first. The number of growth octets (Zn) in the PLCP frame
varies according to the selected PLCP frame format (DS3, DS1, G.751 E3, or E1). The PLCP
frame position indicator (TPOHFP) is set high once per PLCP frame period, during bit 1 of the F1
octet, and indicates the transmit PLCP frame timing. TPOH and TPOHINS are sampled using the
rising edge of TPOHCLK. The bit presented on TPOH is only inserted into the path overhead if
TPOHINS is asserted during the bit in question, or if the appropriate bit is set in the SPLT Control
Register. The timing diagram above assumes that the SRCB1 bit in the SPLT Control Register is
programmed to logic zero, thereby selecting internal insertion of that octet.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
310
PMC [ PMC-SIERRA, INC ]
