CDB61884 Datasheet, PDF (7/22 Pages) Cirrus Logic – Octal T1/E1/J1 Line Interface Evaluation Board

CDB61884
mitters in a high impedance state. Removing the
shorting block, enables the transmitters. See
HI
HI
LO
LO
Enable all eight
tra n s m itte rs
Hi-Z all
eight transmitters
Figure 5. Transmitter Enable Selection
Figure 5.
2.6 Clock Edge Selection
In clock/data recovery mode, jumper J93 selects
the edge of RCLK and SCLK on which the
RPOS/RDATA, RNEG, and SDO data signals are
valid. When in data recovery mode, jumper J93 se-
lects the output polarity of RPOS/RNEG. The func-
tion of J93 applies to both the hardware and host
mode. Figure 6 shows the settings for jumper J93
and the effect in both clock/data recovery and data
recovery only mode.
HI
Clock/Data Recovery -
RPOS/RNEG = falling
edge RCLK SDO =
rising edge SCLK
LO
Data Recovery -
RPOS/RNEG
polarity active high
Clock/Data Recovery -
HI
RPOS/RNEG = rising
edge RCLK SDO =
falling edge SCLK
LO
Data Recovery -
RPOS/RNEG
polarity active low
Figure 6. Clock Edge Selection
In host mode, switch S10 has no effect on the
CS61884 device and should be set to the open
(middle) position.
S10
HIGH
S10
HIGH
S10
HIGH
OPEN
OPEN
OPEN
LOW
JASEL
LOW
JASEL
LOW
JASEL
Hardware Mode
- JA placed in
transmit path
Hardware Mode
- JA Disabled
Hardware Mode
- JA placed in
receive path
Figure 7. Jitter Attenuator Selection
2.8 Loopback Mode Selection
In hardware mode, the Loopback modes are config-
ured with switches S1 through S8 (0-7). Figure 8
shows the three different settings for all eight loop
back switches.
In host mode, switches S1 through S8 must be set
to the NONE (middle) position to allow host inter-
face control.
S1 - S8
S1 - S8
S1 - S8
0-7
Hardware Mode -
Selects Remote
Loopback
0-7
Hardware Mode -
Selects no
Loopback
0-7
Hardware Mode -
Selects local
Loopback
Figure 8. Loopback Mode Selection
2.7 Jitter Attenuator Selection
In hardware mode, switch S10 (JASEL) controls
the position of the jitter attenuator for all eight
channels. The corner frequency and FIFO length
can not be changed in hardware mode. Figure 7
shows the settings for switch S10.
2.9 Line Length Selection
In hardware mode, the transmit pulse shapes for E1
75 Ω, E1 120 Ω and T1(J1) 100 Ω are selected with
switches S12 through S14 (LEN 2-0). Refer to the
CS61884 Data Sheet for the correct settings.
DS485DB1
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