BT8375 CONEXANT [Conexant Systems, Inc], BT8375 Datasheet - Page 189

• Manufacturer Part Number: BT8375
• Description: single chip transceivers for T1/E1 and Integrated Service Digital Network (ISDN) primary rate interfaces
• Manufacturer: CONEXANT [Conexant Systems, Inc]

Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
TNRZ
TABORT
Table 3-19. Transmit Framer Position
TFORCE
N8370DSE
071—Transmitter Configuration (TCR1)
NOTE(S):
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
TABORT
TNRZ
TFSYNC and TMSYNC must be programmed as outputs.
Offline framer examines TPCMI to supply TSB frame alignment.
Online framer examines TPCMI to supply TSB multiframe alignment.
SBI mode must match 2048 k or 1544 k line rate.
TX timebase flywheels at initial alignment until TSB_CTR or TX_ALIGN [addr 0D4].
TSB timebase flywheels if TFSYNC/TMSYNC programmed as outputs.
Offline framer examines TXDATA to supply TX frame alignment.
Online framer examines TXDATA to supply TX multiframe alignment.
7
0
0
1
Transmit NRZ Data—Transmit dual-rail unipolar outputs TPOSO/TNEGO are replaced by
non-return to 0 unipolar data (TNRZO) and transmit multiframe sync (MSYNCO). Both
outputs are clocked on the rising edge of transmitter clock (TCKI). Line encoding of bipolar
signals on XTIP/XRING is unaffected. MSYNCO active (high) always marks the first bit of
transmit multiframe according to the selected transmit framer mode.
Abort/Disable TX Offline Framer—The offline framer ignores reframe requests from the
online framer (TLOF) and aborts any in progress TLOF reframe requests. The loss of frame
status [TLOF; addr 048] is not affected. While TABORT remains active, the offline framer
responds only to the processor force reframe request (TFORCE). This allows the processor to
manually control reframe criteria or lock out changes in the current transmit frame alignment.
online and offline transmit framer during embedded framing modes. If EMBED is active,
TXDATA output from TSLIP is examined and used to align the TX timebase; otherwise, the
TPCMI data stream is examined and used to align the TSB timebase, as defined in
Force TX Reframe (auto clear)—Forces the offline framer to perform a single reframe,
according to the selected transmit framer mode. TFORCE is automatically cleared when the
framer acknowledges a request [ACTIVE; addr 017]. The processor typically does not need to
force a reframe, because the online framer reframe request (TLOF) is active when reframe
criteria TLOFC–A is met. However, the processor may attempt force a reframe if the frame or
CRC bit error ratio indicates that the framer has aligned to a mimic pattern.
EMBED
TABORT
TABORT interacts with EMBED [addr 0D0] to select which data stream is examined by
6
0
1
X
TFORCE
TFSYNC/TMSYNC
TFSYNC/TMSYNC
TSB Alignment
5
TPCMI
0 = TPOSO/TNEGO encoded per TZCS[1:0]
1 = TPOSO/TNEGO replaced by TNRZO/MSYNCO
0 = normal framer operation
1 = framer disabled
0 = no effect
1 = force TX reframe
TLOFC
4
Conexant
Tx Alignment
Flywheel
Flywheel
TXDATA
TLOFB
3
TLOFA
2
Embedded Framing
Tx Framing Mode
Transmit Framing
Normal
TZCS[1]
3.12 Transmitter Registers
1
Table
TZCS[0]
Notes
(1–5)
(6–8)
(5, 6)
0
3-19.
3-71