Altera Corporation
2–93
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
The Receiver Bit Reversal feature is available only in Basic single-width
and Basic double-width modes. If the Receiver Bit Reversal feature is
enabled in Basic single-width mode, the 10-bit data
D[9:0]
at the output
of the word aligner gets rewired to
D[0:9]
. If the Receiver Bit Reversal
feature is enabled in Basic double-width mode without the 8B/10B
decoder, the MSByte
D[15:8]
and LSByte
D[7:0]
at the output of the
word aligner get rewired to
D[8:15]
and
D[0:7]
, respectively. If the
Receiver Bit Reversal feature is enabled in Basic double-width mode with
the 8B/10B decoder, the MSByte
D[19:0]
and LSByte
D[9:0]
at the
output of the word aligner get rewired to
D[0:19]
and
D[0:9]
,
respectively. Flipping the parallel data using this feature allows the
receiver to put out the correctly bit-ordered data on the PLD interface in
case of MSBit to LSBit transmission.
Since the receiver bit reversal is done at the output of the word aligner, a
dynamic bit reversal would also require a reversal of word alignment
pattern. As a result, the Receiver Bit Reversal feature is dynamic only if
the receiver is dynamically reconfigurable (allows changing the word
alignment pattern dynamically) or uses manual bit slip alignment mode
(no word alignment pattern). The Receiver Bit Reversal feature is static in
all other Basic mode configurations and can be enabled through the
MegaWizard Plug-In. In configurations where this feature is dynamic, an
rx_revbitordwa
port is available to control the bit reversal
dynamically. A high on the
rx_revbitordwa
port reverses the bit order
at the input of the word aligner.