XRT83L34_05 Datasheet, PDF (47/99 Pages) Exar Corporation – QUAD T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR

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XRT83L34
QUAD T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR REV. 1.0.1
PATTERN TRANSMIT AND DETECT FUNCTION
Several test and diagnostic patterns can be generated and detected by the chip. In Hardware mode each
channel can be independently programmed to transmit an All Ones pattern by applying a “High” level to the
corresponding TAOS_n pin. In Host mode, the three interface bits TXTEST[2:0] control the pattern generation
and detection independently for each channel according to Table 12.
TABLE 12: PATTERN TRANSMISSION CONTROL
TXTEST2 TXTEST1 TXTEST0
0
x
x
1
0
0
1
0
1
1
1
0
1
1
1
TEST PATTERN
None
TDQRSS
TAOS
TLUC
TLDC
TRANSMIT ALL ONES (TAOS)
This feature is available in both Hardware and Host modes. With the TAOS_n pin connected to a “High” level
or when interface bits TXTEST2=“1”, TXTEST1=“0” and TXTEST0=“1” the transmitter ignores input from
TPOS_n/TDATA_n and TNEG_n/CODES_n pins and sends a continuous AMI encoded all “Ones” signal to the
line, using TCLK_n clock as the reference. In addition, when the Hardware pin and interface bit ATAOS is
activated, the chip will automatically transmit the All “Ones” data from any channel that detects an RLOS
condition. This feature is not available on a per channel basis. TCLK_n must NOT be tied “Low”.
NETWORK LOOP CODE DETECTION AND TRANSMISSION
This feature is available in Host mode only. When the interface bits TXTEST2=”1”, TXTEST1=”1” and
TXTEST0=”0” the chip is enabled to transmit the “00001” Network Loop-Up Code from the selected channel
requesting a Loop-Back condition from the remote terminal. Simultaneously setting the interface bits
NLCDE1=”0” and NLCDE0=”1” enables the Network Loop-Up code detection in the receiver. If the “00001”
Network Loop-Up code is detected in the receive data for longer than 5 seconds, the NLCD bit in the interface
register is set indicating that the remote terminal has activated remote Loop-Back and the chip is receiving its
own transmitted data. When the interface bits TXTEST2=”1”, TXTEST1=”1” and TXTEST0=”1” the chip is
enabled to transmit the Network Loop-Down Code (TLDC) “001” from the selected channel requesting the
remote terminal the removal of the Loop-Back condition.
In the Host mode each channel is capable of monitoring the contents of the receive data for the presence of
Loop-Up or Loop-Down code from the remote terminal. In the Host mode the two interface bits NLCDE[1:0]
control the Loop-Code detection independently for each channel according to Table 13.
TABLE 13: LOOP-CODE DETECTION CONTROL
NLCDE1 NLCDE0
CONDITION
0
0
Disable Loop-Code Detection
0
1
Detect Loop-Up Code in Receive Data
1
0
Detect Loop-Down Code in Receive Data
1
1
Automatic Loop-Code detection and Remote Loop-Back Activation
Setting the interface bits to NLCDE1=”0” and NLCDE0=”1” activates the detection of the Loop-Up code in the
receive data. If the “00001” Network Loop-Up code is detected in the receive data for longer than 5 seconds,
the NLCD interface bit is set to “1” and stays in this state for as long as the receiver continues to receive the
Network Loop-Up Code. In this mode if the NLCD interrupt is enabled, the chip will initiate an interrupt on every
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