8B/10B; Figure 2-3: 8B/10B Parallel-To-Serial Conversion; Figure 2-4: 4-Byte Serial Structure; B/10B - Xilinx RocketIO X User Manual

Block Level Functions

8B/10B

Note:
transceiver the least significant byte is sent first.
The following sections categorize the ports and attributes of the transceiver according to
specific functionality including 8B/10B encoding/decoding, 64B/66B
encoding/decoding, SERDES alignment, clock correction (clock recovery), channel
bonding, fabric interface, and other signals.
The 8B/10B encoding translates an 8-bit parallel data byte to be transmitted into a 10-bit
serial data stream. This conversion and data alignment are shown in
port transmits the least significant bit of the 10-bit data, "a" first and proceeds to "j". This
allows data to be read and matched to the form shown in
Characters."
The serial data bit sequence is dependent on the width of the parallel data. The least
significant byte is always sent first regardless of the whether 1-byte, 2-byte, 4-byte or 8-
byte paths are used. The most significant byte is always last.
the serial data corresponds to each byte of the parallel data. TXDATA[7:0] is serialized and
sent out first followed by TXDATA[15:8], TXDATA[23:16], and finally TXDATA[31:24]. The
2-byte path transmits TXDATA[7:0] and then TXDATA[15:8].
RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004
In the RocketIO transceiver, the most significant byte was sent first; in the RocketIO X
.
H G
7 6
Parallel
a b
0 1
Serial
First transmitted

Figure 2-3: 8B/10B Parallel-to-Serial Conversion

H 3 − A 3
TXDATA 31:24 TXDATA 23:16
a 3 − j 3
LSB 3 LSB 2
4 th Sent
Encoded

Figure 2-4: 4-Byte Serial Structure

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F E D C B
5 4 3 2 1

8B/10B

c d e i f
2 3 4 5 6
H 2 − A 2 H 1 − A 1
TXDATA 15:8
8B/10B
a 2 − j 2 a 1 − j 1
LSB 1
3 rd Sent 2 nd Sent
Encoded Encoded
Figure 2-3. The serial
Appendix B, "8B/10B Valid
A
0
g h j
7 8 9
Last transmitted
UG024_10_021102
Figure 2-4 shows a case when
H 0 − A 0
TXDATA 7:0
a 0 − j 0
LSB 0
1 st Sent
Encoded
ug035_ch3_22_111303
R
47