XRT84L38IB Exar Corporation, XRT84L38IB Datasheet - Page 373

• Manufacturer Part Number: XRT84L38IB
• Description: Network Controller & Processor ICs 8 Ch T1/E1 Framer
• Manufacturer: Exar Corporation

Specifications of XRT84L38IB

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

REV. 1.0.1
The XRT84L38 framer can use two algorithms to search for FAS pattern and thus declare FAS alignment
synchronization. The FAS Selection bit of the Framing Select Register (FSR) allows the user to choose which
one of the two algorithms for searching FAS frame alignment.
The table below shows configurations of the FAS Selection bit of the Framing Select Register (FSR).
FRAMING SELECT REGISTER (FSR) (INDIRECT ADDRESS = 0XN0H, 0X07H)
11.2.2
The CRC-4 Selection [1:0] bits of the Framing Select Register (FSR) enable the framer to search for CRC-4
Multi-frame alignment and select the criteria for locking the CRC-4 Multi-frame alignment.
The table below shows configurations of the CRC-4 Selection [1:0] bit of the Framing Select Register (FSR).
FRAMING SELECT REGISTER (FSR) (INDIRECT ADDRESS = 0XN0H, 0X07H)
11.2.3
The XRT84L38 framer can use two algorithms to search for CAS Multi-frame alignment pattern. Upon
detecting of CAS Multi-frame alignment pattern, the framer will declare CAS Multi-frame alignment
synchronization and generate the Receive CAS Multi-frame synchronization pulse (RxCASMsync_n). The
CAS Selection [1:0] bits of the Framing Select Register (FSR) enable the framer to search for CAS Multi-frame
alignment.
N
N
UMBER
UMBER
B
B
3-2
0
IT
IT
How to configure the framer to enable CRC-4 Multi-frame alignment and select the locking
criteria
How to configure the framer to enable CAS Multi-frame alignment
FAS Selection bit
CRC-4 Selection
B
B
IT
IT
bit
N
N
AME
AME
B
B
IT
IT
R/W
R/W
T
T
YPE
YPE
This Read/Write bit field allows the user to determine which algorithm is
used for searching FAS frame alignment pattern. When an FAS alignment
pattern is found and locked, the XRT84L38 will generate Receive Synchro-
nization (RxSync_n) pulse.
0 - Algorithm 1 is selected for searching FAS frame alignment pattern.
1 - Algorithm 2 is selected for searching FAS frame alignment pattern.
Theses Read/Write bit fields allow the user to enable searching of CRC-4
Multi-frame alignment and determine what criteria are used for locking the
CRC-4 Multi-frame alignment pattern.
00 - Searching of CRC-4 Multi-frame alignment is disabled. The
XRT84L38 framer will not search for CRC-4 Multi-frame alignment and
thus will not declare CRC-4 Multi-frame synchronization. No Receive
CRC-4 Multi-frame Synchronization (RxCRCMsync_n) pulse will be gener-
ated by the framer.
01 - Searching of CRC-4 Multi-frame alignment is enabled. The XRT84L38
will search for and declare CRC-4 Multi-frame synchronization if:At least
one valid CRC-4 Multi-frame alignment signal is observed within 8 ms.
10 - Searching of CRC-4 Multi-frame alignment is enabled. The XRT84L38
will search for and declare CRC-4 Multi-frame synchronization if:At least
two valid CRC-4 Multi-frame alignment signals are observed within 8 ms.
The time separating two CRC-4 Multi-frame alignment signals is multiple
of 2 ms.
11 - Searching of CRC-4 Multi-frame alignment is enabled. The XRT84L38
will search for and declare CRC-4 Multi-frame synchronization if:At least
three valid CRC-4 Multi-frame alignment signals are observed within 8 ms.
The time separating two CRC-4 Multi-frame alignment signals is multiple
of 2 ms.
353
B
B
IT
IT
D
D
ESCRIPTION
ESCRIPTION
OCTAL T1/E1/J1 FRAMER
XRT84L38