Rainbow Electronics DS21458 - Manual (Page 82)

DS21455/DS21458 Quad T1/E1/J1 Transceivers
82 of 270
Bit 3/Local Loopback (LLB). In this loopback, data will continue to be transmitted as normal through the transmit side of the
transceiver. Data being received at RTIP and RRING will be replaced with the data being transmitted. Data in this loopback
will pass through the jitter attenuator.
0 = loopback disabled
1 = loopback enabled
Bit 4/Line Interface Unit Mux Control (LIUC). This bit along with the LIUC/TPD pin and LBCR.7 controls the connection
between the LIU and the Framer. See the LTS (LBCR.7) description below. When the LIUC/TPD pin is connected high or
LBCR.7 = 1, the LIUC bit has control. When the LIUC/TPD pin is connected low the framer and LIU are separated and the
LIUC bit has no effect. For the DS21458 this bit should always be set = 0.
Table 14-1. LIUC CONTROL
LBCR.7
(LTS)
LIUC/TPD
PIN
LBCR.4
(LIUC)
FUNCTION
0 0 0
LIU and Framer Separated
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins active
(This function not available on the DS21458)
0 0 1
LIU and Framer Separated
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins active
(This function not available on the DS21458)
0 1 0
LIU and Framer Connected
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins ignored
(This function not available on the DS21458)
0 1 1
LIU and Framer Separated
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins active
(This function not available on the DS21458)
1 x 0
LIU and Framer Connected
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins ignored
1 x 1
LIU and Framer Separated
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins active
(This function not available on the DS21458)
Bit 5/Unused, must be set to zero for proper operation.
Bit 6/Unused, must be set to zero for proper operation.
Bit 7/LIUC/TPD Pin Function Select (LTS). This bit selects the function the of the LIUC/TPD pin. On the DS21458, this
bit should always be set = 1.
0 = LIUC/TPD pin functions as the LIUC control (This function is not available on the DS21458)
1 = LIUC/TPD pin functions as the TPD control
RECEIVE
LIU
TRANSMIT
LIU
JITTER
ATTENUATOR
JITTER
ATTENUATOR
RECEIVE
FRAMER
TRANSMIT
FRAMER
BACKPLANE
I/F
BACKPLANE
I/F
LOCAL LOOPBACK