Altera SerialLite II Protocol - Manual (Page 28)

28 Altera Corporation
SerialLite II Protocol Reference Manual
Physical Layer Description
adjacent device is an important part of establishing a reliable link. This
acknowledgement is done through the transmission and receipt of
known character sequences to ensure both the near and far end is
operational. The basic operation is as follows: The near transmitter sends
a sequence to the far receiver. When the far receiver detects the sequence
and has performed the character alignment, it causes the far transmitter
to send the acknowledging sequence. When the near receiver detects this
acknowledging sequence and has completed its character alignment, it
causes the near transmitter to send the acknowledging sequence. For a
multi-lane link, the process is repeated to align and bond the lanes. Both
receivers must be locked and confirm lock to the upstream transmitter
before data is transferred.
Figure 2–11 on page 2–28 shows an example of
an acknowledging link.
Figure 2–11. Acknowledging Link Example
For a simplex link implementation, no acknowledgement from the
adjacent device is required as data flows in a single direction. Thus, the
receiver must use a self-synchronizing link state machine to lock onto the
incoming data stream without any feedback to the transmitter. The
transmitter assumes that receiver has achieved link initialization and
sends the data. The clock compensation ordered set can be used for lane
bonding.
Figure 2–12 shows an example of a self-synchronizing link.
Figure 2–12. Self Synchronizing Example
Reset Char Align
Ack Char
Align
Lane
Align
Ack Lane
Align
Link Up
Device A Device B
TD[0-N] RD[0-N]
RD[0-N] TD[0-N]
DAT
IDL
TS2
TS2 TDS
TDS IDL TS1
TS1
OR TS2
Reset Char Align
Ack Char
Align
Lane
Align Ack Lane
Align
Link Up
DAT TS2 TDS IDL TS1
IDL TS2 TDS
TS1
OR TS2
Device A Device B
TD[0-N] RD[0-N]
DAT DAT CC
Reset Char Align
Lane
Align
Link Up
CC DAT
Reset Char Align
Lane
Align
Link Up
DAT