Txchardispval, Txchardispmode - Xilinx RocketIO User Manual

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R
Table 2-10: 8B/10B Bypassed Signal Significance
TXBYPASS8B10B
TXCHARDISPMODE,
TXCHARDISPVAL
RXCHARISK
RXRUNDISP
RXDISPERR
TXCHARISK
RXCHARISCOMMA
TXCHARDISPVAL,
TXCHARDISPMODE
TXCHARDISPVAL and TXCHARDISPMODE are dual-purpose ports for the transmitter
depending upon whether 8B/10B encoding is enabled.
functionality. When encoding is enabled, these ports function as byte-mapped control
ports controlling the running disparity of the transmitted serial data.
In the encoding configuration, the disparity of the serial transmission can be controlled
with the TXCHARDISPVAL and TXCHARDISPMODE ports. When TXCHARDISPMODE
is set High, the running disparity is set before encoding the specific byte.
TXCHARDISPVAL determines if the disparity is negative (set Low) or positive (set High).
Table 2-11
62
8B/10B encoding is enabled (not bypassed). 1, 2, or 4 bits, mapped to number of
0
bytes of data path width.
8B/10B encoding bypassed (disabled). 1, 2, or 4 bits, mapped to number of bytes
1
of data path width.
Function, 8B/10B Enabled
Maintain running disparity normally
00
Invert the normally generated running
01
disparity before encoding this byte.
Set negative running disparity before
10
encoding this byte.
Set positive running disparity before
11
encoding this byte.
Received byte is a K-character
Indicates running disparity is
0
NEGATIVE
Indicates running disparity is
1
POSITIVE
Disparity error occurred on current
byte
Transmitted byte is a K-character
Received byte is a comma
illustrates this.
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Chapter 2: Digital Design Considerations
Function
Function, 8B/10B Bypassed
Part of 10-bit encoded byte
(see Figure 2-13):
TXCHARDISPMODE[0]
(or: [1] / [2] / [3])
TXCHARDISPVAL[0]
(or: [1] / [2] / [3])
TXDATA[7:0]
(or: [15:8] / [23:16] / [31:24])
Part of 10-bit encoded byte
(see Figure 2-14):
RXCHARISK[0]
(or: [1] / [2] / [3])
RXRUNDISP[0]
(or: [1] / [2] / [3])
RXDATA[7:0]
(or: [15:8] / [23:16] / [31:24])
Unused
Unused
Unused
Table 2-10 shows this dual
RocketIO™ Transceiver User Guide
UG024 (v3.0) February 22, 2007