2.0 Circuit Description
2.8 Transmitter
Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
Automatic generation of Yellow Alarm(YB2) is controlled by AUTO_YEL,
RLOF, and RLOF_INTEG. If AUTO_YEL is set, Yellow Alarm is generated
during a Receive Loss of Frame alignment (RLOF = 1). Optionally, RLOF
integration can be enabled by setting RLOF_INTEG. In this case, both RLOF
indication and Yellow Alarm/RAI generation are delayed for approximately 2.5
seconds if a continuous out of frame condition exists. Yellow Alarm/RAI
generation continues for at least 1 second after RLOF clears. Refer to Table 2-13.
Table 2-13. Multiframe Yellow Alarm Generation
Line Rate
Multiframe Yellow Alarm Action
Mode
T1
E1
Facilitates Yellow Alarm Action (requires
programming TDL1)
YF
Set Y bit TS16 in frame 0 to 1
Y16
In T1 ESF framing mode, Multiframe Yellow Alarm or RAI is transmitted
using BOP Codeword Transmitter [TBOP; addr 0A1] and does not depend on
INS_MYEL. Transmitting Yellow Alarm/RAI toward the line can be done upon
receiving Receive Loss of Frame. T1 multiframe Yellow Alarm must be generated
by configuring TDL1 to transmit an all-0s BOP codeword. Optionally, RLOF
integration can be enabled by setting RLOF_INTEG. In this case, both RLOF
indication and Yellow Alarm/RAI generation are delayed for approximately
2.5 seconds if a continuous out of frame condition exists. Yellow Alarm/RAI
generation continues for at least 1 second after RLOF clears. RLOF_INTEG does
not meet the requirements of TR62411. To meet the requirements of TR62411,
“Conditions Causing the Initiation of Carrier Failure Alarms,” the Receive Loss
of Frame condition reported by FRED (addr 049) must be integrated before
initiating Yellow Alarm Transmission. This can be accomplished in software by
integrating FRED during an RLOF Interrupt (ISR7; addr 004), with
RLOF_INTEG bit cleared.
In E1 CAS framing modes, Multiframe Yellow Alarm is inserted into the
transmit stream to alert far-end equipment that local received multiframe
alignment is not recovered. E1 Multiframe Yellow Alarm is transmitted by setting
the Y bit in time slot 16, frame 0.
Transmission of Multiframe Yellow Alarm is controlled by the register bits
listed in Table 2-14:
Table 2-14. Multiframe Yellow Alarm Register Bits
Bit Name
INS_MYEL
Register
[TFRM; addr 072]
[TALM; addr 075]
[TALM; addr 075]
[ALM3; addr 049]
TMYEL
AUTO_MYEL
SRED
2-62
Conexant
N8370DSE
CONEXANT [ CONEXANT SYSTEMS, INC ]
