2–68
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
Figure 2–54. Deserializer Bit Order
Generic Receiver Polarity Inversion
The positive and negative signals of a serial differential link are often
erroneously swapped during board layout. Solutions like a board re-spin
or major updates to the PLD logic can prove expensive. The receiver
polarity inversion feature is provided to correct this situation.
An optional
rx_invpolarity
port is available in all single-width and
double-width modes except (OIF) CEI PHY to dynamically enable the
receiver polarity inversion feature. In single-width modes, a high value
on the
rx_invpolarity
port inverts the polarity of every bit of the 8-bit
or 10-bit input data word to the word aligner in the receiver data path. In
double-width modes, a high value on the
rx_invpolarity
port inverts
the polarity of every bit of the 16-bit or 20-bit input data word to the word
aligner in the receiver data path. Since inverting the polarity of each bit
has the same effect as swapping the positive and negative signals of the
differential link, correct data is seen by the receiver. The
rx_invpolarity
is a dynamic signal and may cause initial disparity
errors in an 8B/10B encoded link. The downstream system must be able
to tolerate these disparity errors.
The generic receiver polarity inversion feature is different from the PIPE
8B/10B polarity inversion feature. The generic receiver polarity inversion
feature inverts the polarity of the data bits at the input of the word aligner.
The PIPE 8B/10B polarity inversion feature inverts the polarity of the
data bits at the input of the 8B/10B decoder and is available only in PIPE
mode. Enabling the generic receiver polarity inversion and the PIPE
8B/10B polarity inversion simultaneously is not allowed in PIPE mode.
Low-Speed RCVD_CLK
01101010
0 1 0
0
0
1
1 1
00000000
00000000
High-Speed RCVD_CLK
rx_datain[0]
rx_dataout[7..0]
Содержание Stratix II GX
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