cx28365 Mindspeed Technologies, cx28365 Datasheet - Page 55

• Manufacturer Part Number: cx28365
• Description: X12, X6, X4 T3/e3 Framer And Atm Cell Transmission Convergence Sublayer Processor
• Manufacturer: Mindspeed Technologies

CX28365/6/4 Data Sheet
500028C
FEBE
The FEBE alarm in DS3 is defined for C-bit parity application only. The three C bits
in M-subframe 4 are used as FEBE bits.
In C-bit parity mode, when the ExtFEBE/Cj-bit in the Transmit Overhead Insertion 1
Control register is set to 0, the FEBE bits are not expected on the TEXTI input pin.
FEBE alarms are automatically generated in the transmitter when the receiver detects
either a frame bit error (F or M-bit error) or a path parity error in an M-frame. The 3-
bit FEBE pattern that is transmitted is contained in the FEBE Pattern Bit Field
(FEBEC/PT[1:3]) of the Feature1 Control register of each framer respectively. When
no alarm condition is present, the FEBE channel contains all 1s. To prevent disabling
proper FEBE operation during the Internal-Auto method of FEBE, the FEBE field
should be written to any combination other than 111.
E3-G.751 Mode
When E3-G.751 mode is set, two alarms can be generated: RAI (Yellow Alarm) and
AIS according to the G.751 standard.
RAI (Yellow Alarm)
Bit 11 set 1 of E3-G.751 frame structure is the A-bit and used to transmit the remote
alarm indication (RAI). RAI alarm is defined as transmitting 1 on A-bit.
Each framer has an option to insert the A-bit:
If automatic RAI is enabled (by setting AutoRAI in Transmit Overhead Insertion 1
Control register to 1), as long as LOS condition or OOF are detected at the receiver,
the transmitter automatically inserts 1 at the transmitted A-bit (starting and stopping
at first opportunity). When LOS and OOF conditions are no longer detected, the
transmitter sets the transmitted A-bit to 0 (no RAI alarm). In the automatic RAI mode
the transmitter side sends automatic RAI as long as OOFAlm or LOSAlm bits at the
Maintenance Status register are set. Detection of LOS and OOF are specified in
Section
Forcing a RAI alarm can also be done by setting TxAlm[1] to 1. As long as TxAlm[1]
is set to 1, A-bit contains 1, regardless of other A-bits sourcing settings.
AIS
E3 AIS is defined as unframed all 1s.
In E3 mode, transmission of AIS is enabled by setting TxAlm0 high. When AIS is
enabled, the framer ignores the inserted data and Overhead bit settings and transmits
an all-1s code as long as TxAlm0 bit is set to 1. Start of AIS transmission and
termination in E3 is immediate with the setting of TxAlm0.
NOTE:
Preliminary Information/Mindspeed Proprietary and Confidential
With payload (when the method of overhead insertion is all with the data stream)
From TEXTI pin
Automatically generate it
Force RAI alarm sending by a control register
2.1.2.4.
Mindspeed Technologies™
FEBE transmission is performed at the first opportunity after framing error or CP
error detection. Automatic FEBE transmission also remains operational (if set) during
receiver OOF, LOS, AIS, or IDLE conditions. When FEBE bits are inserted from an
external pin or with data, the automatic FEBE insertion is disabled and Pattern Bit
Field settings have no meaning—FEBE bits are inserted externally.
Functional Description
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