2.0 Pin Descriptions
RS8953B/8953SPB
2.2 Signal Definitions
HDSL Channel Unit
Table 2-2. Signal Definitions (2 of 4)
Signal
Name
I/O
Description
HDSL Channels
I(1)
BCLK1
Bit Clock
Corresponds to three HDSL and three Auxiliary channels. BCLKn operates at
twice the 2B1Q symbol rate. The rising edge of BCLKn outputs TDATn, TLOADn,
RAUXn and ROHn; the falling edge samples QCLKn, RDATn, and TAUXn inputs.
BCLK2(3)
BCLK3(3)
QCLK1
I(1)
Quaternary Clock
Transmit Data
Operates at the 2B1Q symbol rate (half-bit rate) and identifies sign and
magnitude alignment of both RDATn and TDATn serially encoded bit streams.
The falling edge of BCLKn samples QCLKn: 0 = sign bit; 1 = magnitude bit.
QCLK2(3)
QCLK3(3)
TDAT1
O
HDSL transmit data output at the bit rate on the rising edge of BCLKn. Serially
encoded with the 2B1Q sign bit aligned to the QCLKn low level and the 2B1Q
magnitude bit aligned to the QCLKn high level.
TDAT2(3)
TDAT3(3)
TAUX1
I(1)
Transmit
Auxiliary Data
HDSL transmit auxiliary data input sampled on the falling edge of BCLKn when
TLOADn is active. TAUXn replaces data normally supplied by PCM or HDSL
transmitters to the HDSL scrambler input. Payload bytes or Z-bits can be
mapped from TAUXn.
TAUX2(3)
TAUX3(3)
RDAT1
I(1)
Receive Data
HDSL receive data input sampled on the falling edge of BCLKn. The serially
encoded 2B1Q sign bit is sampled when QCLKn is low, and the 2B1Q magnitude
bit is sampled when QCLKn is high.
RDAT2(3)
RDAT3(3)
RAUX1
Receive Auxiliary
Data
O
Receives data from the HDSL descrambler output on the rising edge of BCLKn.
Includes all SYNC, STUFF, HOH, payload, and Z-bits. RAUXn shares pin locations
with DROP, INSERT, and MSYNC, as controlled by RAUX_EN (CMD_6; addr
0xF3).
RAUX2(3)
RAUX3(3)
TLOAD1
Transmit Load
Indicator
O
O
Active-high output that indicates when specific payload or Z-bits are sampled at
TAUXn. TLOADn is active for 8 bits coincident with each marked payload byte or
1 bit for Z-bits. The last 40 Z-bits or any combination of payload bytes may be
marked.
TLOAD2(3)
TLOAD3(3)
ROH1
Receive Overhead
Indicator
Indicate when overhead is received. Has two modes of operation:
• RAS = 0. ROHn is high to mark only data passed into the RFIFO.
• RAS=1. ROHn is high to mark only the last 40 Z-bits.
ROH2(3)
ROH3(3)
2-8
Conexant
N8953BDSB
CONEXANT [ CONEXANT SYSTEMS, INC ]
