BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 60

• Manufacturer Part Number: BT8954
• Description: VOICE PAIR GAIN FRAMER
• Manufacturer: CONEXANT [Conexant Systems, Inc]

4.0 Registers
4.4 Transmitter Registers
EN_AUTO_TFIFO
_RST
REPEAT_EN
NUM_SBITS[3:0]
SCRAM_TAP
DD_LOOP
4-8
0x87—Transmit Command Register 2 (TCMD_2)
TFIFO_RST
EN_AUTO_
7
REPEAT_EN
Enable Automatic TFIFO_RST—When set, the TFIFO is reset the instant that the Receive
Framer changes state from SYNC_ACQUIRED to IN_SYNC.
Enable Repeater Mode—When set, DSL frames received on RDAT are re-transmitted with
new overhead after bypassing all the FIFOs.
Number of valid S-Bits in each TSFIFO and RSFIFO register—
Scrambler Tap—Selects which delay stage, 5th or 18th, to tap for feedback in the transmit
scrambler. The system’s DSL terminal type dictates which scrambler tap should be selected.
For the repeater (Figure 2):
Loopback to DSL on the DSL Side—Receive DSL data (RDAT) is switched to transmit DSL
data (TDAT) to accomplish a loopback of the DSL channel on the DSL side. Loopback data is
switched at I/O pins and does not alter DSL receive operations. If the DSCRAM_EN
[RCMD_2; 0x91.5] and SCAM_EN [TCMD_1; 0x86.0] bits are set, RDAT is switched to
TDAT after descrambling and scrambling.
6
5
0 = TFIFO not automatically reset by SYNC_ACQUIRED
1 = TFIFO automatically reset by SYNC_ACQUIRED
0 = Normal transmit
1 = Repeater mode
0 = No S-bits transmitted or received
1
0 = HTU-C or LTU terminal type, scrambler taps 5th delay stage
1 = HTU-R or NTU terminal type, scrambler taps 18th delay stage
0 = Bt8954 (C
1 = Bt8954 (R
0 = Normal transmit
1 = TDAT supplied by RDAT pin
8 = 1
4
NUM_SBITS[3:0]
Conexant
8 valid S-bits in each TSFIFO and RSFIFO register
R), scrambler tapes 5th delay stage
C), scrambler tapes 18th delay stage
3
2
SCRAM_TAP
Voice Pair Gain Framer
1
IN_SYNC
IN_SYNC
N8954DSC
DD_LOOP
Bt8954
0