BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 59

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

Bt8954
Voice Pair Gain Framer
Real-time commands (bits 0–5) are sampled by the OH multiplexer on the respective transmit frame to affect
operation in the next outgoing frame. DOH_EN and FORCE_ONE command bit combinations provide the
transmit data encoding options needed to perform standard DSL channel start-up procedures.
TEST_TSFIFO
FORCE_ONE
DOH_EN
ICRC_ERR
SCRAM_EN
N8954DSC
0x86—Transmit Command Register 1 (TCMD_1)
—
7
Test Transmit Signaling FIFO—Enables the copying of TSFIFO_I into TSFIFO_O by the MC,
so that the TSFIFOs can be tested from the MC.
Force All 1s Payload—Transmit payload data bytes are replaced by all 1s. FORCE_ONE and
SCRAM-EN are set, and DOH_EN is cleared to enable output of a 4-level framed scrambled
1s signal.
DSL Overhead Enable—The OH multiplexer inserts EOC, IND, and CRC bits. Otherwise,
transmit overhead bits, except SYNC WORD, are forced to 4-level 1s.
Inject CRC Error—Logically inverts the 6 calculated CRC bits in the next frame.
Scrambler Enable—All transmit DSL channel bits, except SYNC WORD bits, are scrambled
per the SCR_TAP setting in TCMD_2 [0x87]. Otherwise, transmit data passes through the
scrambler unchanged.
—
6
—
5
0 = Disable testing of TSFIFOs; enable normal operation
1 = Enable testing of TSFIFOs; disable normal operation
0 = Normal payload transmission
1 = Force 4-level 1s payload
0 = OH transmitted as 4-level 1s
1 = Normal OH transmission
0 = Normal CRC transmission
1 = Transmit errored CRC
0 = Scrambler bypassed
1 = Scrambler enabled
TEST_TSFIFO
4
Conexant
FORCE_ONE
3
DOH_EN
2
ICRC_ERR
4.4 Transmitter Registers
1
4.0 Registers
SCRAM_EN
0
4-7