STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Register 017H: RJAT Configuration
Bit
Type
Function
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Unused
Unused
Unused
CENT
X
X
X
0
0
0
0
1
R/W
R/W
R/W
R/W
R/W
UNDE
OVRE
FIFORST
LIMIT
CENT:
The CENT bit allows the FIFO to self-center its read pointer, maintaining the
pointer at least 4 UI away from the FIFO being empty or full. When CENT is
set to logic 1, the FIFO is enabled to self-center for the next 384 transmit data
bit period, and for the first 384 bit periods following an overrun or underrun
event. If an EMPTY or FULL alarm occurs during this 384 UI period, the
period will be extended by the number of UI that the EMPTY or FULL alarm
persists. During the EMPTY or FULL alarm conditions, data is lost. When
CENT is set to logic 0, the self-centering function is disabled, allowing the
data to pass through uncorrupted during EMPTY or FULL alarm conditions.
The recommended value of CENT is logic 1.
UNDE:
Setting the UNDE bit to logic 1 enables an underrun event to assert the INTB
output low.
OVRE:
Setting the OVRE bit to logic 1 enables an overrun event to assert the INTB
output low.
FIFORST:
Setting the FIFORST bit allows the FIFO to reset when the PLL is reset by
software. When FIFORST is logic 1, writing to the PLL Divider Control
Registers N1 and N2 will cause both the PLL and FIFO to reset. When
PROPRIETARY AND CONFIDENTIAL
117
PMC [ PMC-SIERRA, INC ]
