Altera SerialLite II Protocol - Manual (Page 36)

36 Altera Corporation
SerialLite II Protocol Reference Manual
Data Link Layer Description
1. All data characters are scrambled, except those contained in the
training pattern.
2. The special characters are not scrambled.
3. The COM character initializes the LFSR with value of 0xFFFF
XOR
ed with the lane number (LN).
4. The LFSR advances by 8-bit shifts for each data and special
character, except for the IDL (skip) control symbol.
5. The LFSR scrambling operation acts independently for each lane.
Data Link Layer
Description This sections describes the Data Link layer of the SerialLite II protocol.
Packet Description
The SerialLite II protocol supports two different packet types: user
packets and link management packets.
User Packets
User packets carry either high-priority user data or regular user data.
User Packet Types
The SerialLite II protocol supports two different user packet types: data
packets and priority packets. A priority packet contains high-priority
data or status information and takes precedence over regular data
packets. Retry-on-error is an added benefit of priority packets to handle
error conditions and increase reliability of the link. Typically, data packets
are better suited for carrying a continuous flow of packets with a low
latency requirement.
User Packet Length
Table 2–17 shows the supported lengths for the user packet types.
Table 2–17. User Packet Length Range
Packet Type Minimum Frame Length Maximum Frame Length
Data 1 character Unlimited
Priority 1 character Unlimited