2–92
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
Run-Length Violation Detection Circuit
The programmable run-length violation circuit resides in the word
aligner block and detects consecutive 1s or 0s in the data. If the data
stream exceeds the preset maximum number of consecutive 1s or 0s, the
violation is signified by the assertion of the
rx_rlv
signal.
This signal is not synchronized to the parallel data and appears in the
logic array earlier than the run-length violation data. To ensure that the
PLD can latch this signal in systems where there are frequency variations
between the recovered clock and the PLD logic array clock, the
rx_rlv
signal is asserted for a minimum of two clock cycles in single-width
modes and a minimum of three clock cycles in double-width modes. The
rx_rlv
signal may be asserted longer, depending on the run-length of
the received data.
In single-width mode, the run-length violation circuit detects up to a run
length of 128 (for an 8-bit deserialization factor) or 160 (for a 10-bit
deserialization factor). The settings are in increments of 4 or 5 for the 8-bit
or 10-bit deserialization factors, respectively.
In double-width mode, the run-length violation circuit maximum
run-length detection is 512 (with a run-length increment of 8) and 640
(with a run-length increment of 10) for the 16-bit and 20-bit
deserialization factors, respectively.
Table 2–21
summarizes the detection capabilities of the run-length
violation circuit.
Receiver Bit Reversal
By default, the Stratix II GX receiver assumes an LSBit to MSBit
transmission. If the transmission order is MSBit to LSBit, then the receiver
will put out the bit-flipped version of the data on the PLD interface. The
Receiver Bit Reversal feature is available to correct this situation.
Table 2–21. Run-Length Violation Circuit Minimum and Maximum Range
Data Path
Deserialization
Factor
Run-Length Violation Detector Range
Minimum
Maximum
Single-width
8
4
128
10 5
160
Double-width
16
8
512
20
10
640
Содержание Stratix II GX
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