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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
5
The “Test and Diagnostic” section provides the UNI
IC with the following capabilities.
Allows the UNI to operate in the Line, Cell, and
PLCP Loop-back Modes
Contains an internal Test Cell Generator and an
internal Test Cell Receiver. The Test Cell Generator
will generate Test Cells with “user-defined” header
byte patterns. The Test Cell Generator will also fill
the payload portion of these test cells with bytes
from an on-chip PRBS generator.
The Test Cell Generator can generate test cells in
“One Shot” Mode (e.g., a burst of 1024 test cells) or in
“Continuous” Mode (e.g., a continuous stream of
test cells).
The Test Cell Receiver will identify and collect the
Test Cells for further analyses, based upon the
“user-defined” header byte patterns. Additionally,
the Test Cell Receiver will report the occurrence of
any errors by incrementing an on-chip register.
LINE INTERFACE DRIVE AND SCAN SECTION
The Line Interface Drive and Scan Section allows the
user to monitor and control many aspects of the
XRT7295 DS3 Line Receiver IC and the XRT7296
DS3 Line Transmitter IC, via on-chip registers, within
the UNI IC. This feature eliminates the need for glue
logic to interface the XRT7245 DS3 UNI to the
XRT7295/XRT7296 DS3 Line Interface Unit ICs.
The On-Chip Line Interface Drive register allows
the user to control the state of 6 output pins. The
function of these output pins, when asserted, are
tabulated below.
Signal Name
Function of Output Pin
REQB
Receive Equalizer By-Pass:
Setting this bit-field to “1” configures the XRT7300 device to shut off its internal Receive Equalizer.
Setting this bit-field to “0” configures the XRT7300 device to enable its internal Receive Equalizer.
TAOS
Transmit “All Ones” Pattern.
Setting this bit-field to “1” configures the XRT7300 LIU IC to overwrite the DS3 data that is output via
the TxPOS and TxNEG outputs, and transmit an “All Ones” pattern onto the line.
Setting this bit-field to “0” configures the XRT7300 LIU IC to transmit data, as is applied to it via the
TPDATA and TNDATA input pins.
ENCODIS
B3ZS Encoder Disable/Enable Select.
Setting this bit-field to "1" disables the B3ZS Encoder, within the XRT7300 device.
Setting this bit-field to "0" enables the B3ZS Decoder within the XRT7300 device.
TxLev
Transmit Output Signal Line Build Out Select.
Setting this bit-field to “1” disables the Transmit Line Build Out circuitry within the XRT7300 device. In
this case, the XRT7300 will generate an “unshaped” square wave signal out onto the line (via the TTIP
and TRING output pins).
Note:
In order to configure the XRT7300 device to generate a line signal that complies with the Transmit
Output Pulse Template Requirements (per GR-499-CORE), this setting is advised if the cable length
between the Transmit Output of the XRT7300 device and the Cross-Connect is greater than 225 feet.
Setting this bit-field to “0” enables the Transmit Line Build Out circuitry within the XRT7300 device. In
this case, the XRT7300 device will generate a “shaped” square wave out onto the line (via the TTIP and
TRING output pins).
Note:
In order to configure the XRT7300 device to generate a line signal that complies with the Transmit
Output Pulse Template Requirements (per GR-499-CORE), this setting is advised if the cable length
between the Transmit Output of the XRT7300 device and the Cross-Connect is less than 225 feet.