Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.8 Receiver Registers
049—Alarm 3 Status (ALM3)
Reports real-time status of the receive framer (not affected by ONESEC latch mode), and miscellaneous latched
error status (SEF and RMAIS). Any change of the logical OR of FRED, MRED, or SRED status activates the
RLOF interrupt [ISR7; addr 004]. Refer to Table 3-2, Receive Framer Modes [RFRAME; addr 001] to find the
criteria for loss/recovery of frame alignment.
7
6
5
4
3
2
1
0
—
RMAIS
SEF
SRED
MRED
FRED
LOF[1]
LOF[0]
RMAIS
Receive TS16 Alarm Indication Signal (CAS mode only)—RMAIS is latched active high and
cleared by a processor read. The criteria for detection and clearance of RMAIS is per ITU
G.775.
Mode
CAS
RMAIS Criteria
Set if TS16 contains three or fewer zeros out of 128 bits in each
mutiframe over two consecutive multiframes (4 ms).
Other
Not applicable (read 0).
SEF
Severely Errored Frame—SEF is latched active high and cleared by a processor read. Criteria
for detection and clearance of SEF is per ANSI T1.231.
Mode
E1
SEF Criteria
Set if two or more (FAS or NFAS) errors are detected out of six
frames. (FAS + NFAS, or 2 FAS, or 2 NFAS errors, etc.).
FT/SF/SLC Set if two or more Ft errors are detected out of 3 Ft bits.
ESF Set if two or more FPS errors detected out of 6 FPS bits.
SRED
MRED
FRED
Loss of CAS Alignment—Real-time status of CAS alignment machine. SRED is applicable if
CAS is enabled; otherwise SRED is 0.
0 = recovery of CAS alignment
1 = loss of CAS alignment
Loss of MFAS Alignment—Real-time status of MFAS alignment machine. MRED is
applicable if MFAS is enabled; otherwise MRED is 0.
0 = recovery of MFAS alignment
1 = loss of MFAS alignment
Loss of T1/FAS Alignment—Real-time status of basic frame alignment machine. The FRED
alarm counter [AERR; addr 05A] increments for each low-to-high FRED transition.
0 = recovery of frame alignment
1 = loss of frame alignment.
LOF[1:0]
Reason for Loss of Frame Alignment—LOF status is latched whenever FRED reports a loss of
frame alignment and remains held at the latched value until the next loss of frame alignment.
LOF[1:0]
LOF Criteria
Three consecutive FAS pattern errors
00
01
10
11
Three consecutive NFAS pattern errors
915 or more CRC4 errors out of 1000 blocks checked
8 ms timeout while searching for MFAS
N8370DSE
Conexant
3-57
CONEXANT [ CONEXANT SYSTEMS, INC ]
