Altera Interlaken MegaCore Function - Manual (Page 42)

4–16 Chapter 4: Functional Description
Transmit Path
Interlaken MegaCore Function June 2012 Altera Corporation
User Guide
TX MAC
The Interlaken MegaCore function TX MAC performs the following functions:
■ Inserts burst and idle control words in the incoming data stream.
■ Repacks the data to ensure the maximum number of words is available on each
valid clock cycle.
■ Calculates and inserts CRC-24 bits in all burst and idle words.
■ Inserts calendar data in all burst and idle words.
■ Stripes the data across the PCS lanes. The MSB of the data goes to lane 0.
■ Buffers data between the application and the TX PCS block in the TX FIFO buffer.
The TX PCS block uses the FIFO buffer to recover bandwidth when the number of
words delivered to the transmitter is less than the full width.
Figure 4–11 shows the flow through the Interlaken TX MAC block.
For more information about the correspondence between lane numbers and output
signals, refer to
Table 5–1 on page 5–2 .
TX PCS
The Interlaken MegaCore function TX PCS block performs the following functions for
each lane:
■ Inserts the meta frame words in the incoming data stream.
■ Calculates and inserts the CRC-32 bits in the meta frame diagnostic words.
■ Scrambles the data according to the scrambler seed and the protocol-specified
polynomial.
Figure 4–11. Data Flow Through Interlaken MegaCore Function TX MAC Block
To TX PCS Lanes
Striping
TX
FIFO
Buffer CRC-24 Repacking Burst Control Word
Insertion