Xilinx RocketIO X User Manual page 56

R
Table 2-9: Data Alignment
ALIGN_COMMA_WORD
The attribute ALIGN_COMMA_WORD controls when realignment takes place when the
difference between symbols is on a byte-by-byte basis. If the current position of the symbol
detected is some fraction of a byte different than the previous symbol position, alignment
takes place regardless of the setting of ALIGN_COMMA_WORD.
•
RXSLIDE
RXSLIDE can be used to "slide" the aligned data by one bit. The RXSLIDE function when
asserted High, increments the alignment by one bit, until it reaches the most significant bit,
equal to the maximum word length –1. When RXSLIDE is asserted High, it must be
asserted Low for two clock periods before it can be asserted High again. This functionality
can be used for applications such as SONET.
56
ENMCOMMAALIGN
1
Notes:
1. The symbol mentioned is defined by P/MCOMMA_10B_VALUE.
There are three options for ALIGN_COMMA_WORD: 1 byte, 2 byte, and 4 byte.
When ALIGN_COMMA_WORD is set to a 1, the detection circuit allows detection
symbols in contiguous bytes. When ALIGN_COMMA_WORD is set to a 2, the
detection circuit allows detection symbols every other byte. When
ALIGN_COMMA_WORD is set to a 4, the detection circuit allows detection symbols
every fourth byte.
16/20
1 byte alignment
2 N/A
4 2-byte alignment
ALIGN_COMMA_WORD = 1
Note: Shaded blocks indicate where the comma can align to.
Chapter 2: Digital Design Considerations
ENPCOMMAALIGN
1
32/40
byte alignment
2-byte alignment
4-byte alignment
Four Byte Internal
7 6 5 4 3 2 1 0
2
4
8-Byte Fabric IF
www.xilinx.com
1-800-255-7778
(1)
Function
If a negative or positive
symbol is detected, alignment
takes place at that symbol
location.
Two Byte Internal
3 2 1 0
Do not use
1 Byte Fabric IF
2 Byte Fabric IF
4 Byte Fabric IF
ug035_ch2_13111604
RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004