BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 23

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

Figure 3-1. Block Diagram
N8954DSC
QCLK
HCLK
BCLK
RDAT
TDAT
LB
Receiver
Transmitter
3.0 Circuit Descriptions
3.1 Overview
Figure 3-1
the bit stream is received from the DSL bit pump, the Receive Framer detects the
beginning of the Digital Subscriber Line (DSL) frame, and generates the required
pulses for synchronizing the different demultiplexing functions. The Payload
Demux block strips overhead bits from the DSL frame and puts the payload for
the different Pulse Code Multiplexed (PCM) time slots into the PCM RFIFO.
The PCM RFIFO is emptied through the PCMR pin.
Payload data from the TFIFO is multiplexed with signaling data from the
signaling registers and overhead from the OH (overhead) registers. The
multiplexed data is then sent to the DSL bit pump, through the TDAT pin, after
being 2B1Q encoded.
The PCMCLK, ADPCMCK, and the internal clock are generated and
synchronized to BCLK with the PLL. The PLL uses HCLK as its clock reference.
Decoder
Encoder
2B1Q
On the transmit side, the PCM TFIFO is filled with serial data on PCMT.
PCM and DSL loopback functions are performed using the loopback blocks.
2B1Q
PLL
details the major blocks and pins of Bt8954. After the 2B1Q decode of
OH/Signaling
Registers
Receive
Payload
Payload
Framer
Demux
Mux
Conexant
Microcomputer Interface
3
RFIFO
TFIFO
PCM
PCM
Microcomputer
LB
PCMR
ADPCMCK
PCMCLK
PCMF[18:1]
PCMT
3-1