Altera 100G Interlaken MegaCore Function User Manual
Page 46
In cycle 2, the following two events occur:
• The first data burst completes. The application asserts
itx_eob
, indicating the data the application
transfers to the IP core in this clock cycle is the end of the burst. The value the application drives on
itx_num_valid[7:4]
indicates that one word in this data symbol is valid data associated with this
burst. In addition, the application drives
itx_eopbits
to the value of 4'b0000 to indicate that the data
the application transfers to the IP core in this clock cycle is not the end of the packet. Therefore, all
bytes in this data word are valid.
• A second data burst starts at Word 3. This transfer is a dual segment transfer, as is allowed whether or
not the IP core is configured in dual segment mode on the RX side. The application asserts
itx_sop[0]
and
itx_sob[0]
, indicating that this cycle is both the start of the burst and the start of the
packet, and that data in this burst and packet starts from Byte 31 of the data symbol. The application
drives the value of 3 on
itx_chan
to indicate the data originates from channel 3. The value of
itx_num_valid[3:0]
is 4'b0100, indicating this data transfer is a dual segment data transfer—that it
begins at Word 3. The value of
itx_num_valid[7:4]
has no relevance for the data words in this burst
that appear in this data symbol, except to indicate the previous burst includes no data in these words of
the data symbol (Words 3 through 0), and therefore, that they are available for the second data burst.
As is required, the dual segment data transfer places valid data in all four words in the least significant
half of the data symbol.
In cycles 3 and 4, the second data burst continues with no EOB or EOP indication. The IP core does not
sample the value of
itx_chan
in these clock cycles, and its value is therefore a Don't Care. The value on
itx_num_valid[7:4]
indicates that all eight words in each of these data symbols are valid data associated
with this burst.
In cycle 5, the following two events occur:
• The second data burst completes. The application asserts
itx_eob
, indicating the data transfered in
this clock cycle is the end of the burst. The value the application drives on
itx_num_valid[7:4]
indicates that four words in this data symbol are valid data associated with this burst. In addition, the
value the application drives on
itx_eopbits
indicates the data is the end of the packet, and that all
eight bytes of the final data word are valid data bytes.
• A third data burst starts at Word 3. This transfer is a dual segment transfer, as is allowed whether or
not the IP core is configured in dual segment mode on the RX side. The application asserts
itx_sob[0]
, indicating that this cycle is the start of the burst and that data in this burst starts from
Byte 31 of the data symbol. However, the application does not assert
itx_sop[0]
, indicating this burst
is not the first burst in the packet. The value the application drives on
itx_chan
indicates the data
originates from channel 2. Therefore, we can conclude this data burst is the second burst in a packet
from channel 2. The value the application drives on
itx_num_valid[3:0]
is 4'b0100, indicating this
data transfer is a dual segment data transfer—that it begins at Word 3. The value of
itx_num_valid[7:4]
has no relevance for the data words in this burst that appear in this data symbol,
except to indicate the previous burst includes no data in these words of the data symbol (Words 3
through 0), and therefore, that they are available for the second data burst. As is required, the dual
segment data transfer places valid data in all four words in the least significant half of the data symbol.
In cycle 6, the third data burst completes. The application asserts
itx_eob
, indicating the data transfered
in this clock cycle is the end of the burst. The value on
itx_num_valid[7:4]
indicates that five words in
this data symbol are valid data associated with this burst. In addition, the value the application drives on
itx_eopbits
indicates the data is the end of the packet, and that all eight bytes of the final data word are
valid data bytes. Because the data from this burst occupies words 7 through 3 of the data symbol, another
burst cannot start in the current data symbol.
4-16
100G Interlaken IP Core Dual Segment Interleaved Data Transfer Transmit Example
UG-01128
2015.05.04
Altera Corporation
Functional Description