Altera SerialLite II Protocol - Manual (Page 65)

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SerialLite II Protocol Reference Manual
SerialLite II Specification
Segment Identification (SID)
The four-bit segment identification field gets its information from the
upper nibble of the SPP2 field (see
Table 2–19 ). The four-bit SID field
cycles from 0 to 15, and repeats. The segment identification has the
following characteristics:
1. This field is implemented regardless of whether or not retry-on-
error is enabled.
2. This field is incremented with each segment transmitted.
3. The segment identification field is valid from 0x0 to 0xF.
Segment Buffers
A set of buffers must be provided in the transmitter to store every
segment after transmission, until the segment is acknowledged. This
storage allows the segments to be retransmitted if they were not
successfully received.
The following rules apply to the buffer:
1. Eight segment size buffers must be provided.
2. The segment size must be 2 N columns, the smallest being eight
columns.
3. No segment can be released from its buffer until it has been
successfully acknowledged.
4. Segments must be released in sequence.
Table 2–23. Retry-On-Error Packet Parameter Values
Parameter Bit Width Valid Settings
CLASS 4 0x0 = ACK
0x1 = NACK
All other values are reserved for future use.
SID 4 Value from 0x0 to 0xF
It identifies the starting segment for
retransmission.