RS8953B/8953SPB
3.0 Circuit Descriptions
HDSL Channel Unit
3.5 HDSL Channel
3.5.1.7 HDSL Auxiliary
Transmit
The HDSL auxiliary transmit channel provides an alternate source of HDSL
payload bytes and optionally, an alternate source for the last 40 Z-bits transmitted
in each HDSL frame. Auxiliary transmit data (TAUXn) is sampled by BCLKn
whenever TLOADn is active-high, as shown in Figures 3-20 and 3-21. TLOADn
is enabled by TAUX_EN [TCMD_2; addr 0x07] and programmed in the Transmit
Payload Map Registers [TMAP; addr 0x08]. TLOADn marks specific payload
bytes selected in the TMAP registers or marks the last 40 Z-bits depending on the
setting of EXT_ZBIT [TCMD_2; addr 0x07].
Figure 3-20. HDSL Auxiliary Channel Payload Timing
BCLK
Sign Mag
QCLK
X1 X2 X3 X4 X5 X6 X7 X8
TAUX
TAUX_EN = 1
EXT_ZBIT = 0
byte1
TLOAD
TAUX Throughput Delay
SW SW SW SW SW SW SW SW SW SW SW SW SW SW
IND IND
Z1 X1 X2
TDAT
1
2
3
4
5
6
7
8
9
10 11 12 13 14
0
1
NOTE(S): TLOAD shows transmit payload map byte1, TMAP = 11. In this case:
TLOAD pulses high during auxiliary input sampling of byte1 in all payload blocks (B1-B48).
Figure 3-21. HDSL Auxiliary Channel Z-bit Timing
Z
48
Z
9
Z
10
Z
11
TAUX
TAUX_EN = 1
EXT_ZBIT = 1
TLOAD
TAUX Throughput Delay
Z
47
Z
48
Z
1
Z
2
Z
3
Z
4
Z
5
Z
6
Z
7
Z
8
Z
9
Z
10
Z
11
B47
B48
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
TDAT
NOTE(S): TAUX throughput delay varies by STUFF bit insertion, shown for illustration only.
N8953BDSB
Conexant
3-27
CONEXANT [ CONEXANT SYSTEMS, INC ]
