Altera Stratix GX Transceiver - Manual (Page 171)

Altera Corporation 6–17
January 2005 Stratix GX Transceiver User Guide
GigE Mode
the same as the beginning running disparity (right before the idle code).
This rule ensures a negative running disparity at the end of an idle
ordered set. A /Kx.y/ following a /K28.5/ is not replaced.
Figure 6–17 shows the input data codes versus the output data codes. The
/D14.3/ , /D24.0/, and /D15.8/ code groups were replaced by
/D5.6/ or /D16.2/ (for /I1/ and /I2/ ordered sets), and /D21.5/
(part of the /C2/ ordered set) was not replaced.
Figure 6–17. Input Data Codes vs. Output Data Codes
8B/10B Encoder
The 8B/10B encoder is part of the Stratix GX transceiver block. The
8B/10B encoder translates 8-bit data and a 1-bit control identifier (by
using the tx_ctrlenable signal) into a 10-bit, DC-balanced data
stream.
For more information about the 8B/10B code, refer to the 8B/10B Code
section in the Appendix. The 8B/10B encoder translates the 8-bit data or
8-bit control character to its 10-bit equivalent.
Figure 6–18 shows the
conversion format. The serializer sends the 10-bit data in order from LSB
to MSB.
clock
tx_in[ ]
K28.5 D14.3 K28.5 D24.0 K28.5 D15.8 K28.5 D21.5
Order Set
tx_out
Dx.y K28.5 D5.6 K28.5 D16.2 K28.5 D16.2 K28.5
/C2/ /I2/ /I2/ /I1/
Dx.y
D21.5