STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Register 031H: BRIF Frame Pulse Configuration
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
MAP
0
0
1
0
0
0
0
0
FPINV
FPMODE
ALTFDL
ROHM
BRXSMFP
BRXCMFP
ALTBRFP
MAP:
The MAP bit determines the mapping of a 2.048 MHz backplane onto a
1.544 MHz line. This bit is ignored when in E1 mode (E1/T1B register bit is
logic 1), when the backplane rate is 1.544 Mbit/s (RATE[1:0] = 'b00), or when
in clock master mode (CMODE = 'b0).
When MAP is a logic 0, every fourth time slot is unused, starting with time slot
0. The framing bit is presented during bit 0 of time slot 0, so that only bits 1
to 7 of time slot 0 are unused.
When MAP is a logic 1, the first 24 time slots (0 to 23) are used. The framing
bit is sampled during bit 7 of time slot 31 and the rest of the frame (time slots
24 to 30 and bits 0 to 6 of time slot 31) does not contain valid data.
FPINV:
The frame pulse inversion (FPINV) bit determines whether BRFP is inverted
prior to sampling or presentation. If FPINV is a logic 0, BRFP is active high.
If FPINV is a logic 1, BRFP is active low.
FPMODE:
The frame pulse mode (FPMODE) bit determines whether BRFP is an input
or an output. When FPMODE is a logic 0, frame pulse master mode is
selected, BRFP is an output and the ROHM, BRXSMFP, BRXCMFP and
ALTBRFP bits determine what BRFP connotes.
PROPRIETARY AND CONFIDENTIAL
140
PMC [ PMC-SIERRA, INC ]
