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Altera Corporation
2–111
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
Control Detect
The 8B/10B decoder indicates to the PLD logic array the difference
between data and control codes through the
rx_ctrldetect
port. This
port is optional but, if not in use, there is no way to differentiate a Dx.y
from a Kx.y.
In double-width mode, the
rx_ctrldetect
port is 2-bits wide inside
the PCS. The lower bit indicates if the LSByte is a control word or data,
and the upper bit indicates if the MSByte is a control word or data. When
a control word is decoded, the corresponding
rx_ctrldetect
bit goes
high. For data, the corresponding
rx_ctrldetect
bit goes low. The
rx_ctrldetect
port in the PLD logic array is edge-aligned with the
code group it is associated with.
Figure 2–88
shows an example waveform that shows the receipt of a
K28.5 code (BC + ctrl). The
rx_ctrldetect=2'b1
is aligned with 8’hbc
on the LSByte, indicating that it is a control code. The 8’hbc on the MSByte
is a data, not a control word. The rest of the codes received are Dk.y
control codes.
Figure 2–88. Control Code Detection
Reset
The reset for the 8B/10B decoder block is derived from the receiver digital
reset (
rx_digitalreset
). When
rx_digitalreset
is asserted, the
8B/10B decoder block resets. In reset, the disparity registers are cleared
and the outputs of the 8B/10B decoder block are driven low. After reset,
the 8B/10B decoder starts with either a positive or negative disparity,
depending on the disparity of the data it receives. The decoder calculates
the initial running disparity based on the first valid code received.
1
The receiver block must be word aligned after reset before the
8B/10B decoder can decode valid data or control codes. If word
alignment has not been achieved, the data from the 8B/10B
decoder is discarded and considered invalid.
clock
rx_dataout[15..0]
rx_ctrldetect[1..0]
83 78
BC BC
0F 00
BF 3C
D3.4
D24.3
D28.5
K28.5
D15.0
D0.0
D31.5
D28.1
Code Group
0
1
0
Содержание Stratix II GX
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