Rainbow Electronics DS21458 - Manual (Page 80)

DS21455/DS21458 Quad T1/E1/J1 Transceivers
80 of 270
FRAMER LOOPBACK
RECEIVE
LIU
TRANSMIT
LIU
JITTER
ATTENUATOR
JITTER
ATTENUATOR
RECEIVE
FRAMER
TRANSMIT
FRAMER
BACKPLANE
I/F
BACKPLANE
I/F
14. LOOPBACK CONFIGURATIONS
The DS21455/DS21458 have four loopback configurations including Framer, Payload, Local, and
Remote loopback.
Figure 14-1 depicts a normal signal flow without any loopbacks enabled .
Payload loopback may be done on a per-channel basis if both the transmit and receive paths are
synchronous (RCLK = TCLK and RSYNC = TSYNC). See Section
14.1 .
Figure 14-1. Normal Signal Flow Diagram
Register Name:
LBCR
Register Description: Loopback Control Register
Register Address: 4Ah
Bit
# 7 6 5 4 3 2 1 0
Name LTS — — LIUC LLB RLB PLB FLB
Default 0 0 0 0 0 0 0 0
Bit 0/Framer Loopback (FLB).
0 = loopback disabled
1 = loopback enabled
NORMAL MODE
RECEIVE
LIU
TRANSMIT
LIU
JITTER
ATTENUATOR
JITTER
ATTENUATOR
RECEIVE
FRAMER
TRANSMIT
FRAMER
BACKPLANE
I/F
BACKPLANE
I/F