bt8970 Mindspeed Technologies, bt8970 Datasheet - Page 49

• Manufacturer Part Number: bt8970
• Description: Single-chip Hdsl Transceiver
• Manufacturer: Mindspeed Technologies

Bt8970
Single-Chip HDSL Transceiver
0x06—Channel Unit Interface Modes Register (cu_interface_modes)
tbclk_pol
rbclk_pol
fifos_mode
interface_
mode[1,0]
100101B
Interface
mode
[1:0]
7
00
01
10
11
–
Parallel Master —Parallel quat transfer
synchronized to QCLK out.
Parallel Slave—Parallel quat transfer
synchronized to separate TBCLK and
RBCLK inputs.
Serial, Magnitude First. Serial quat
transfer synchronized to BCLK out;
magnitude-bit first followed by sign
bit.
Serial, Sign First. Serial quat transfer
synchronized to BCLK out; sign-bit
first followed by magnitude bit.
Transmit Baud Clock Polarity—Read/write control bit defines the polarity of the TBCLK
input while in the parallel slave interface mode. When set, TQ[1,0] is sampled on the falling
edge of TBCLK; when cleared, TQ[1,0] is sampled on the rising edge.
Receive Baud Clock Polarity—Read/write control bit defines the polarity of the RBCLK input
while in the parallel slave interface mode. When set, RQ[1,0] is updated on the falling edge of
RBCLK; when cleared, RQ[1,0] is updated on the rising edge.
FIFO’s Mode—Read/write control bit used to stagger the transmit and receive FIFO’s read and
write pointers while in the parallel slave interface mode. A logic one forces the pointers to a
staggered position, while a logic zero allows them to operate normally. Must be first set, then
cleared once after QCLK-TBCLK-RBCLK frequency lock is achieved to maximize
phase-error tolerance.
Interface Mode—Read/write binary field specifies one of four operating modes for the
channel unit interface.
6
–
Preliminary Information/Conexant Proprietary and Confidential
Mode
5
–
tbclk_pol
4
Conexant
TBCLK
used
used
used
Not
Not
Not
91
rbclk_pol
3
RBCLK
used
used
used
Not
Not
Not
90
fifos_mode
RQ[1]
RQ[1]
2
RDAT
RDAT
Pin Functions
88
interface_mode[1] interface_mode[0]
RQ[0]
RQ[0]
BCLK
BCLK
89
1
TQ[1]
TQ[1]
TDAT
TDAT
85
4.0 Register
0
TQ[0]
TQ[0]
used
used
Not
Not
86
4-5