Altera Interlaken MegaCore Function - Manual (Page 43)

Chapter 4: Functional Description 4–17
Receive Path
June 2012 Altera Corporation Interlaken MegaCore Function
User Guide
■ Performs 64/67 encoding. The input to this function is 65 bits wide; the most
significant bit is an Altera-defined control bit that indicates whether a word is a
control word or a data word. The control bit has value 1 if the current word is a
control word, and value 0 if the current word is a data word.
■ Performs 67/20 gearboxing. For the 12-lane, 10-Gbps variation, performs 67/40
gearboxing.
Figure 4–12 shows the flow through the Interlaken TX PCS block.
Receive Path
The Interlaken MegaCore function receives data on the Interlaken link and sends it
through to the two application channels. The RX PCS and MAC blocks retrieve the
data and calendar information from the incoming Interlaken link and send it out to
two RX channel filtering blocks. The RX channel filtering blocks separate the data for
the two channels, and the packet regroupers regroup each channel’s data in the word
format expected on the channels.
RX PCS
To retrieve the data, the PCS block reverses the gearboxing and 64/67 encoding, then
descrambles the data, and validates the CRC-32 bits and the meta frame. The RX PCS
block also sends lane status information to the calendar and status block.
Figure 4–12. Data Flow Through Interlaken MegaCore Function TX PCS Block
Gearbox
67
64/67 Encoder
Scrambler
65
64
CRC-32 +
Framing
Scheduler
20 or 40