Figure 1-31: Byte Deserializer in Double-Width Mode
Byte
Deserializer
Receiver PCS Clock
/2
D1D2
D3D4
D5D6
D7D8
D2D4
D7D8
datain[15:0]
or
datain[19:0]
dataout[31:0]
or
dataout[39:0]
D1D2
D5D6
Byte Ordering
When you enable the byte deserializer, the output byte order may not match the originally transmitted
ordering. For applications that require a specific pattern to be ordered at the LSByte position of the data,
byte ordering restores the proper byte order of the byte-deserialized data before forwarding it to the FPGA
fabric.
Byte ordering operates by inserting a predefined pad pattern to the byte-deserialized data if the predefined
byte ordering pattern found is not in the LSByte position.
Byte ordering requires the following:
• A receiver with the byte deserializer enabled
• A predefined byte ordering pattern that must be ordered at the LSByte position of the data
• A predefined pad pattern
Byte ordering supports operation in single- and double-width modes. Both modes support operation in
word aligner-based and manual ordering modes.
Byte Ordering in Single-Width Mode
Byte ordering is supported only when you enable the byte deserializer.
Table 1-28: Byte Ordering Operation in Single-Width Mode
Pad Pattern Length
Byte Ordering
Pattern Length
8B/10B Decoder
FPGA
Fabric–Transceiver
Interface Width
PMA–PCS Interface Width
8 bits
8 bits
Disabled
16 bits
8 bits
9 bits
(3)
9 bits
(3)
Enabled
16 bits
10 bits
10 bits
10 bits
Disabled
20 bits
(3)
The MSB of the 9-bit pattern represents the 1-bit control identifier of the 8B/10B-decoded data. The lower 8
bits represent the 8-bit decoded code.
Transceiver Architecture in Cyclone V Devices
Altera Corporation
CV-53001
Byte Ordering
1-46
2013.05.06