Altera SerialLite II Protocol - Manual (Page 44)

44 Altera Corporation
SerialLite II Protocol Reference Manual
Data Link Layer Description
2. The continuation of packet sequences {CDP} and {CPP} must be
transmitted on lane number N-2 of a new column similar to SDP
and SPP.
3. The break must occur on a data burst boundary defined by the
transfer size. The data transfer before the break can not be partially
filled with IDL characters, except upon then end-of-packet.
4. If the CRC option is enabled, the bytes are placed immediately
following EGP, EBP, or SUP.
5. Suspending the transfer of a priority packet must be on the segment
size boundary.
Multi-Lane Alignment
SerialLite II allows the data path to be transparently sent across the link
with in-band overhead carrying control information. For a multi-lane
link, the most significant byte (MSB) of the user interface is transmitted
on the most significant lane. The user data must present data to the user
interface following the big-endian convention. Symbols are transmitted
such that the first byte is sent on lane number 0, the second byte on lane
number 1, and so on. The mapping is simplified for a single lane
implementation as it is a degenerative case.
Multi-Lane Alignment Rules for Packets
The following multi-lane alignment rules must be followed:
1. The start-of-packet sequences for user packets ({SDP}, {SPP}, {CDP},
and {CPP}) begin in lane number N-2.
2. If a packet ends before the end of a column boundary, all remaining
unused lanes to the {EGP} are filled with IDL characters.
3. The end-of-packet sequences ({EGP} and {EBP}) and suspend-packet
sequence ({SUP}) are transmitted in lane number 0.
4. Payload protection {CRC} is appended to either {EGP}, {EBP}, or
{SUP}.
5. The start-of-packet sequence for link management packets begin in
lane number 0.
6. Mixing user data and control symbols is not allowed, except for IDL
at the end of a user packet.