Vitesse Disparity Example; Figure 3-10: 10-Bit Tx Data Map With 8B/10B Bypassed; Figure 3-11: 10-Bit Rx Data Map With 8B/10B Bypassed - Xilinx RocketIO User Manual

PLL Operation and Clock Recovery
Table 3-12: 8B/10B Bypassed Signal Significance (Continued)
RXDISPERR
TXCHARISK
RXCHARISCOMMA
During transmit, while 8B/10B encoding is enabled, the disparity of the serial
transmission can be controlled with the TXCHARDISPVAL and TXCHARDISPMODE
ports. When 8B/10B encoding is bypassed, these bits become Bits "b" and "a", respectively,
of the 10-bit encoded data that the transceiver must transmit to the receiving terminal.
Figure 3-10
During receive, while 8B/10B decoding is enabled, the running disparity of the serial
transmission can be read by the transceiver from the RXRUNDISP port, while the
RXCHARISK port indicates presence of a K-character. When 8B/10B decoding is
bypassed, these bits remain as Bits "b" and "a", respectively, of the 10-bit encoded data that
the transceiver passes on to the user logic.
8B/10B bypass.

Vitesse Disparity Example

To support other protocols, the transceiver can affect the disparity mode of the serial data
transmitted. For example, Vitesse channel-to-channel alignment protocol sends out:
or
Instead of:
or
The logic must assert TXCHARDISPVAL to cause the serial data to send out two negative
running disparity characters.
UG024 (v1.5) October 16, 2002
RocketIO™ Transceiver User Guide
Disparity error occurred on current byte Unused
Transmitted byte is a K-character
Received byte is a comma
illustrates the TX data map during 8B/10B bypass.
TXCHARDISPMODE[0]
TXCHARDISPVAL[0]
a b
0 1
First transmitted

Figure 3-10: 10-Bit TX Data Map with 8B/10B Bypassed

RXCHARISK[0]
RXRUNDISP[0]
a b
0 1
First received

Figure 3-11: 10-Bit RX Data Map with 8B/10B Bypassed

K28.5+ K28.5+ K28.5- K28.5-
K28.5- K28.5- K28.5+ K28.5+
K28.5+ K28.5- K28.5+ K28.5-
K28.5- K28.5+ K28.5- K28.5+
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1-800-255-7778
Unused
Unused
TXDATA[7] . . .
c d e i f
2 3 4 5 6
Figure 3-11
RXDATA[7] . . .
c d e i f
2 3 4 5 6
. . . TXDATA[0]
g h j
7 8 9
Last transmitted
UG024_10a_051602
illustrates the RX data map during
. . . RXDATA[0]
g h j
7 8 9
Last received
UG024_10b_051602
R
59