Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.12 Transmitter Registers
072—Transmit Frame Format (TFRM)
TFRM controls the insertion of overhead bits generated by transmit frame and alarm formatters. Bypassed
overhead bits flow transparently from TPCMI system bus input through TSLIP buffer.
7
6
5
4
3
2
1
0
—
—
INS_MYEL
INS_YEL
INS_MF
INS_FE
INS_CRC
INS_FBIT
INS_MYEL
Insert Multiframe Yellow Alarm—Applicable to E1 modes only. Enables the alarm formatter
to output Y16 Multiframe Yellow Alarm. Once enabled, TMYEL and AUTO_MYEL [addr
075] control the alarm output state. This bit must be set to 0 in T1 modes. In ESF framed T1
mode, the YF Multiframe Yellow Alarm is transmitted by programming the DL1 data link
controller and transmitting the appropriate bit oriented code message (BOP message).
0 = bypass
1 = insert multiframe Yellow Alarm
INS_YEL
Insert Yellow Alarm—The alarm formatter outputs Yellow Alarms YB2 or YJ during T1
modes, or Y0 during E1 modes. Once enabled, TYEL and AUTO_YEL [addr 075] control the
Yellow Alarm output state. If the system wants to bypass JYEL (Fs bit in frame 12), it must
bypass all Fs bits with INS_MF [addr 072].
0 = bypass
1 = insert Yellow Alarm.
INS_MF
INS_FE
Insert Multiframe Alignment—The frame formatter outputs 6-bit SF alignment pattern in T1
mode, or 6-bit MFAS alignment pattern in E1 mode. INS_MF must be set while TFRAME
(addr 070) selects Fs (T1) or MFAS (E1) alignment.
0 = bypass
1 = insert multiframe alignment
Insert FEBE—During E1 mode, the alarm formatter automatically outputs TS0 bit 1 of frames
13 (FEBE13) and 15 (FEBE15) in response to received CRC4 errors. FEBE13 is active low for
each received CRC4 error detected in SMF I; FEBE15 is active low for each received CRC4
error detected in SMF II. INS_FE should be set while TFRAME (addr 070) selects FEBE (E1)
alignment.
0 = bypass
1 = insert FEBE
INS_CRC
INS_FBIT
Insert Cyclic Redundancy Check—The frame formatter outputs the calculated CRC6 bits in
T1 mode or CRC4 bits in E1 mode.
0 = bypass
1 = insert cyclic redundancy check
Insert Terminal Framing—The frame formatter outputs a 2-bit Ft alignment pattern in F-bits of
odd frames (SF framing) or FPS framing pattern (ESF framing) during T1 modes—or 8-bit
FAS/NFAS alignment pattern during E1 modes. INS_FBIT should be set while TFRAME
(addr 070) selects Ft (T1, SF), FPS (T1, ESF), or FAS (E1) alignment.
NOTE:
If F-bits are bypassed while TSLIP is enabled, the system must use either embedded
T1 framing or apply at least a double frame (250 µs) multiframe sync pulse
(TMSYNC) to provide odd/even frame alignment.
0 = bypass
1 = insert terminal framing
N8370DSE
Conexant
3-73
CONEXANT [ CONEXANT SYSTEMS, INC ]
