DS21Q55N Maxim Integrated Products, DS21Q55N Datasheet - Page 83

• Manufacturer Part Number: DS21Q55N
• Description: Framer E1/J1/T1 3.3V 256-Pin BGA
• Manufacturer: Maxim Integrated Products

Specifications of DS21Q55N

• Package: 256BGA
• Number Of Transceivers: 4
• Standard Framing Format: E1|J1|T1
• Maximum Supply Current: 75(Typ) mA
• Minimum Single Supply Voltage: 3.135 V
• Maximum Single Supply Voltage: 3.465 V

12.3 Frames Out-of-Sync Count Register (FOSCR)
12.3.1 T1 Operation
The FOSCR is used to count the number of multiframes that the receive synchronizer is out of sync. This
number is useful in ESF applications needing to measure the parameters loss-of-frame count (LOFC) and
ESF error events as described in AT&T publication TR54016. When the FOSCR is operated in this
mode, it is not disabled during receive loss-of-synchronization (RLOS = 1) conditions. The FOSCR has
an alternate operating mode whereby it counts either errors in the Ft framing pattern (in the D4 mode) or
errors in the FPS framing pattern (in the ESF mode). When the FOSCR is operated in this mode, it is
disabled during receive loss-of-synchronization (RLOS = 1) conditions.
FOSCR is capable of counting.
Table 12-D. T1 Frames Out-of-Sync Counting Arrangements
12.3.2 E1 Operation
The FOSCR counts word errors in the FAS in time slot 0. This counter is disabled when RLOS is high.
FAS errors are not counted when the framer is searching for FAS alignment and/or synchronization at
either the CAS or CRC4 multiframe level. Since the maximum FAS word error count in a one-second
period is 4000, this counter cannot saturate.
The frames out-of-sync count register 1 (FOSCR1) is the most significant word and FOSCR2 is the least
significant word of a 16-bit counter that records frames out-of-sync.
Register Name:
Register Description:
Register Address:
Bit #
Name
Default
Bits 0 to 7/Frames Out-of-Sync Counter Bits 8 to 15 (FOS8 to FOS15). FOS15 is the MSB of the 16-bit frames
out-of-sync count.
Register Name:
Register Description:
Register Address:
Bit #
Name
Default
Bits 0 to 7/Frames Out-of-Sync Counter Bits 0 to 7 (FOS0 to FOS7). FOS0 is the LSB of the 16-bit frames out-
of-sync count.
FRAMING MODE
(T1RCR1.3)
ESF
ESF
D4
D4
FOS15
FOS7
7
0
7
0
FOS14
FOS6
FOSCR1
Frames Out-of-Sync Count Register 1
46h
FOSCR2
Frames Out-of-Sync Count Register 2
47h
6
0
6
0
COUNT MOS OR
F-BIT ERRORS
(ERCNT.1)
FOS13
FOS5
MOS
F-Bit
MOS
F-Bit
5
0
5
0
FOS12
FOS4
4
0
4
0
83 of 237
Errors in the Ft pattern
Number of multiframes out-of-sync
Number of multiframes out-of-sync
Errors in the FPS pattern
FOS11
FOS3
COUNTED IN THE FOSCRs
0
0
3
3
FOS10
FOS2
2
0
2
0
FOS9
FOS1
1
0
1
0
Table 12-D
FOS8
FOS0
0
0
0
0
shows what the