
XRT7250
DS3/E3 FRAMER IC
á
REV. 1.1.1
82
The local P can determine the current state of the
AIS condition by reading bit 7 of the Rx E3 Configura-
tion and Status Register (Address = 0x11).
NOTE: For more information on the AIS Condition please
see Section 4.3.2.8.
2.3.4.6
Receive E3 Interrupt Status Register -
2 (E3, ITU-T G.751)
Bit 3 - FERF (Change in FERF Condition) Interrupt
Status
This Reset Upon Read bit will be set to '1' if the Re-
ceive E3 Framer has detected a Change in the Rx
FERF Condition, since the last time this register was
read.
This bit-field will be asserted under either of the fol-
lowing two conditions.
1. When the Receive E3 Framer first detects the
occurrence of an Rx FERF Condition (e.g., when
the FERF bit, within the last 3 or 5 consecutive
E3 frames are set to "1").
2. When the Receive E3 Framer detects the end of
the Rx FERF Condition (e.g., when the FERF bit,
within the last 3 or 5 consecutive E3 frames are
set to "0").
NOTE: For more information on the Rx FERF (Yellow
Alarm) condition, please see Section 4.3.2.9.
Bit 2 - BIP-4 (Detection of BIP-4) Error Interrupt
Status
This Reset-upon-Read bit-field will be set to "1" if the
BIP-4 Error interrupt has occurred since the last read
of this register.
The Receive E3 Framer will generate the BIP-4 Error
interrupt if it has concluded that it has received an er-
rored E3 frame, from the Far-End Terminal.
NOTE: Please see Section 4.3.6.1.7 for a more detailed dis-
cussion of this interrupt.
Bit 1 - Framing Error Interrupt Status
This Reset-upon-Read bit-field will be set to "1" if the
Framing Byte Error interrupt has occurred since the
last read of this register.
The Receive E3 Framer will generate the Framing Er-
ror interrupt if it has detected an error in the FAS (or
Framing Alignment), in an incoming E3 frame.
NOTE: Please see Section 4.3.6.1.8 for a more detailed dis-
cussion of this interrupt.
2.3.4.7
Receive E3 LAPD Control Register (E3,
ITU-T G.751)
Bit 2 - RxLAPD Enable
This Read/Write bit-field allows the user to enable or
disable the LAPD Receiver, for reception of incoming
LAPD Message frames from the Remote LAPD
Transmitter.
Writing a "1" to this bit-field enables the LAPD Re-
ceiver. Writing a "0" to this bit-field disables the LAPD
Receiver.
Bit 1 - RxLAPD (Received LAPD Message) Inter-
rupt Enable
RXE3 INTERRUPT STATUS REGISTER - 2 (ADDRESS = 0X15)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
FERF
Interrupt
Status
BIP-4
Error
Interrupt
Status
Framing
Error
Interrupt
Status
Not Used
RO
RUR
00
000
RXE3 LAPD CONTROL REGISTER (ADDRESS = 0X18)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
RxLAPD
Enable
RxLAPD
Interrupt
Enable
RxLAPD
Interrupt
Enable
RO
R/W
RUR
00
000