Altera Interlaken MegaCore Function - Manual (Page 47)

Chapter 4: Functional Description 4–21
Calendar and Status Block
June 2012 Altera Corporation Interlaken MegaCore Function
User Guide
Figure 4–16 shows the calendar and status block and its sub-blocks in an Interlaken
MegaCore function with Expose calendar ports turned on.
Lane Status Block
The lane status block monitors the health of the Interlaken RX PCS lanes and delivers
the status information to output status signals for use by the application. It also passes
the lane status information to the TX calendar control block.
TX Calendar Control Block and In-Band Flow Control Calendar Bits
The calendar and status block handles the in-band flow control calendar bits
differently, depending on whether you configure your Interlaken MegaCore function
with Expose calendar ports turned on or turned off. The following sections describe
the MegaCore function behavior in the two cases.
Behavior with Hidden Calendar Ports
If you turn off Expose calendar ports in the Interlaken parameter editor, the
Interlaken MegaCore function uses only two of the 16 available in-band calendar bits.
Bit 0 is a XON/XOFF bit for channel 0, and bit 1 is a XON/XOFF bit for channel 1. To
indicate to the Interlaken link partner that channel 0 or channel 1 cannot accept more
data, the Interlaken MegaCore function sets TX calendar bit 0 or 1 to zero.
The TX calendar control block sets all the TX calendar bits to 1 at initialization — after
the RX lanes and link are fully locked (in other words, the RX Operational state
specified in the Interlaken specification is reached). The TX calendar control block
holds all 16 of the TX calendar bits at value 1 for the duration of IP core operation,
because the RX datapath can handle all incoming traffic and does not need to
backpressure its Interlaken link partner.
Figure 4–16. Calendar and Status Block Connections with Exposed Calendar Ports
Interlaken MegaCore Function
TX Calendar
Control
TX
PCS
TX
MAC
RX
PCS
RX
MAC
Lane
Status
Status
Counters
Calendar
and
Status
crc24_error
locked status
RX calendar
TX calendar
TX calendar
Arbiter
enable
Channel 0
Channel 1
data
sop
eop
channel
data
sop
eop
data
sop
eop
HSIO
Block