STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Register 005H: Transmit Framing and Bypass Options
Bit
Type
Function
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
PATHCRC
G706ANNBRAI
SIGAEN
0
0
0
0
0
0
0
0
OOCMFE0
FDIS
FBITBYP
CRCBYP
FDLBYP
This register allows software to configure the bypass and framing options of the
transmitter, the use of the Signaling Alignment block, and controls the global
transmit framing disable.
PATHCRC:
This bit only has effect in E1 mode.
When in E1 mode, the PATHCRC bit allows upstream block errors to be
preserved in the transmit CRC bits. If PATHCRC is a logic 1, the CRC-4 bits
are modified to reflect any bit values in BTPCM which have changed prior to
transmission. When PATHCRC is set to logic 0, a new CRC-4 value
overwrites the incoming CRC-4 word. For the PATHCRC bit to be effective,
the FPTYP bit of the Transmit Backplane Frame Pulse Configuration register
must be a logic 1; otherwise, the identification of the incoming CRC-4 bits
would be impossible. The PATHCRC bit only takes effect if the GENCRC bit
of the E1-TRAN Configuration register is a logic 1 and either the INDIS or
FDIS bit in the same register are set to logic 1.
G706ANNBRAI:
When in E1 mode, the G.706 Annex B RAI bit, G706ANNBRAI, selects
between two modes of operation concerning the transmission of RAI when
the COMET is out of CRC-4 multiframe. When G706ANNBRAI is logic 1, the
behaviour of RAI follows Annex B of G.706, i.e., RAI is transmitted only when
out of basic frame, not when CRC-4-to-non-CRC-4 interworking is declared,
nor when the offline framer is out of frame. When G706ANNBRAI is logic 0,
the behaviour of RAI follows ETSI standards, i.e., RAI is transmitted when out
PROPRIETARY AND CONFIDENTIAL
87
PMC [ PMC-SIERRA, INC ]
