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STANDARD PRODUCT
PMC-Sierra, Inc.
PM6344 EQUAD
PMC-951013
ISSUE 5
QUADRUPLE E1 FRAMER
203
13.3.2
Line Loopback
When LINE loopback (LINELB) is initiated by writing 10H to the Master
Diagnostics Register, the framer is configured to internally connect the dual-rail
positive and negative line data pulses output from CDRC to the dual-rail inputs of
DJAT. If either the transmit or receive is in unipolar mode, the appropriate line
decoding or encoding is performed. Conceptually, the data flow through a single
framer in this loopback condition can be shown as follows:
Figure 29
- Line Loopback
DTIF
DJAT
TRAN
CDRC
FRMR
ELST
BTSIG[x]
BTPCM[x]
BTCLK[x]
BTFP[x]
BRFPI
BRCLK
BRPCM[x]
S
RPCM
RCLK
RP
RN
N
RDP/RDD[x]
RDN/RLCV[x]
RCLKI[x]
TDP/TDD[x]
TCLKO[x]
TDN/TFLG[x]
13.3.3
Diagnostic Digital Loopback
When Diagnostic digital loopback (DDLB) is initiated by writing 04H to the Master
Diagnostics Register, the framer is configured to internally connect the data and
clock outputs from the DJAT to the CDRC. When the framer is configured for
dual-rail operation (RUNI=0, TUNI=0), the dual-rail positive and negative data
pulses output from DJAT are connected to the dual-rail inputs of CDRC.
Clock recovery can be enabled or disabled in the CDRC and diagnostic digital
loopback will also operate when the framer is configured for single-rail operation
(RUNI=1, TUNI=1).