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S/UNI-QUAD
PMC-Sierra, Inc.
PM5349 S/UNI-QUAD
DATASHEET
PMC-971239 ISSUE 6 SATURN USER NETWORK INTERFACE (155-QUAD)
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
208
13.5
Loopback Operation
The S/UNI-QUAD supports three loopback functions: line loopback, parallel
diagnostic loopback and serial diagnostic loopback. Each channel's loopback
modes operate independently. The loopback modes are activated by the PDLE,
LLE and SDLE bits contained in the S/UNI-QUAD Channel Control Register.
The line loopback, see Figure 14, connects the high speed receive data and
clock to the high speed transmit data and clock, and can be used for line side
investigations (including clock recovery and clock synthesis). While in this mode,
the entire receive path is operating normally and cells can be received through
the FIFO interface.
The serial diagnostic loopback, see Figure 15, connects the high speed transmit
data and clock to the high speed receive data and clock. While in this mode, the
entire transmit path is operating normally and data is transmitted on the TXD+/-
outputs.
The parallel diagnostic loopback, see Figure 16, connects the byte wide transmit
data and clock to the byte wide receive data and clock. While in this mode, the
entire transmit path is operating normally and data is transmitted on the TXD+/-
outputs.