Altera Stratix GX Transceiver - Manual (Page 135)

Altera Corporation 5–23
January 2005 Stratix GX Transceiver User Guide
XAUI Mode
Figure 5–19. Transmitter Output During Reset Conditions
Note to Figure 5–19 :
(1) K28.5 is an example, but an 07 control generates an idle sequence based on the 802.3 specification.
Control Code Encoding
The tx_ctrlenable[] signal dictates when a control code is to be
inserted in the encoded data flow. When tx_ctrlenable[] is low, the
byte at tx_in[] is encoded as data. When tx_ctrlenable[] is high,
tx_in[]
is encoded as a control word. The waveform in Figure 5–20
shows that 0x07 is encoded as a control code. The other values of
tx_in[]
are encoded as data.
Figure 5–20. Control Word Identification Waveform
The 8B/10B encoder does not check to see if the code word that is entered
is one of the 12 valid codes. If an invalid control code is entered, the
resulting 10-bit code might be encoded as an invalid code, which does not
map to a valid Dx.y or Kx.y code), or a valid Dx.y code, depending on the
value entered.
clock
tx_out[9:0 ]
txdigitalreset
K28.5- K28.5- K28.5- xxx xxx xxx K28.5- k28.5+ K28.5- Dx.y+
(1)
clock
tx_in[7:0]
tx_ctrlenable
83 78 BC 07 0F 00 BF 3C
D3.4 D24.3 D28.5 K28.5 D15.0 D0.0 D31.5 D28.1 Code Group