8b/10b reset condition – Altera Stratix GX Transceiver User Manual
Page 64
3–18
Altera Corporation
Stratix GX Transceiver User Guide
January 2005
Basic Mode Transmitter Architecture
For additional information regarding the 8B/10B code itself, refer to
Appendix A, Data & Control Codes
. The 8B/10B encoder translates the 8-
bit data or 8-bit control character to its 10-bit equivalent. The conversion
format is shown in
. The 10-bit resultant data is transmitted
LSB first by the serializer.
Figure 3–16. 8B/10B Conversion Format
8B/10B Reset Condition
The txdigitalreset controls the reset of the 8B/10B encoder. To reset
the 8B/10B encoder, txdigitalreset must be high. During reset, the
running disparity registers are cleared, as are the data registers. Also, the
8B/10B encoder outputs a K28.5 pattern from the RD- column
continuously until txdigitalreset is low. The tx_in[] and
tx_ctrlenable[]
are ignored during the reset state. Once out of reset,
the 8B/10B encoder starts with a bias towards negative disparity (RD-)
and transmits three K28.5 code for synchronizing before it starts encoding
and transmitting the data on tx_in[].
If the reset for the 8B/10B encoder is asserted, the 8B/10B decoder
receiving the data might receive an invalid code error, sync error, control
detect, and/or disparity error while txdigitalreset is high.
7
6
5
4
3
2
1
0
H
G
F
E
D
C
B
A
8b-10b conversion
7
6
5
4
3
2
1
0
9
8
g
f
i
e
d
c
b
a
j
h
LSB sent first
MSB sent last
+ CTRL