Altera SerialLite II Protocol - Manual (Page 57)

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SerialLite II Protocol Reference Manual
SerialLite II Specification
The data link layer transparently passes the channel number; it is up to
the end user to create the design that delivers the data from the multiple
channels for transmission, and then to ensure that the data received is
handled correctly.
Channel multiplexing is only permitted when transmitting packets.
Streaming applications cannot use the channel multiplexing capability.
Data Packets
The SDP2 field in the start-of-data packet sequence is used, optionally, to
transmit an 8-bit channel number. This allows a system to identify up to
256 data channels. If the channel multiplexing feature is not required, the
channel number must be set to 0.
To confirm the integrity of the channel number, this information is
verified at the end of the transferred segment. The SUP2/EGP2/EBP2
field must contain the same channel number to ensure that the data has
been sent to the correct channel. If the SUP2/EGP2/EBP2 channel
number does not match the CDP2/SDP2 channel number, an error must
be flagged.
Priority Packets
The SPP2 field is divided into two sections, as shown in Table 2–19 .
The lower nibble is used, optionally, by the user to convey a channel
number and is mapped into the lower nibble of the SPP2 field, allowing
identification of up to 16 data streams. If the channel multiplexing feature
is not required, the channel number must be set to 0.
The upper nibble contains a segment identification number and is used
for the retry-on-error feature, as described in
“Segment Identification
(SID)” on page 2–65 .
To confirm the integrity of the segment ID and channel number, this
information is verified at the end of the transferred segment. The
SUP2/EGP2/EBP2 field must contain the same segment ID and channel
number to ensure that the data has been sent to the correct channel. If the
SUP2/EGP2/EBP2 channel number does not match the CPP2/SPP2
channel number, an error must be flagged.
Table 2–19. SPP2 Field Format
Bit[7:4] Bit[3:0]
Segment ID Channel number