Gearbox; Decoder; Descrambler - Xilinx RocketIO X User Manual

R

Gearbox

Bypassing
If the signal TXGEARBOX64B66BUSE is deasserted Low, the gearbox is not used. The
gearbox should always be enabled when using the 64/66 protocol.
Normal Operation
If the signal TXGEARBOX64B66BUSE is asserted High, the gear box is enabled. The
gearbox frames 64B/66B data for the PMA.

Decoder

Bypassing
If RXDEC64B66BUSE is deasserted Low, the entire 64B/66B decoder is not used.
Normal Operation
If RXDEC64B66BUSE is asserted High, the 64B/66B decoder decodes according to the
64B/66B block format table shown in
If the signal RXIGNOREBTF is asserted High, block type fields not recognized are passed
on, whereas if the signal is asserted Low, the error block /E/ is passed on. RXCHARISK is
equivalent to RXC when the decoder is enabled.
0 decoder not used
RXDEC64B66BUSE
1 decoder used
Function 64B/66B decoder used
RXIGNOREBTF 0 unrecognized field types cause /E/ passed on
1 unrecognized field types passed on
equivalent to RXC
RXCHARISK

Descrambler

Bypassing
If the signal RXDESCRAM64B66BUSE is deasserted Low, the descrambler is not used.
Normal Operation
If the signal RXDESCRAM64B66BUSE is asserted High, the descrambler is enabled for use.
The descrambler uses the polynomial:
60
TXGEARBOX64B66BUSE
39
G(x) = 1 + x + x
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0
1 always set to '1' when scrambler and
descrambler are enabled.
Figure 2-6.
Function 64B/66B decoder bypassed
undefined
defined by 8B/10B decoder use
58
RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004