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58 www.xilinx.com SPI-4.2 Lite v4.3 User Guide
UG181 June 27, 2008
Chapter 4: Designing with the Core
R
Sink User Interface
The Sink User Interface includes all the signals to the core other than those on the SPI-4.2
Interface (See “SPI-4.2 Interface,” page 53). The high performance Sink back-end enables
the user interface to run at higher frequencies than the SPI-4.2 Interface. This is sometimes
required if a large percentage of traffic consists of small packets.
The user interface has three major sections:
• Control and Status Signals: These signals apply to the operation of the entire Sink
core
• FIFO Interface Signals: These signals allow you to access the data received on the
SPI-4.2 Interface
• Status and Flow Control Signals: These signals are used to send flow control
information on the SPI-4.2 Interface
Sink Control and Status Signals
These signals control the operation of the entire Sink core or provide status information not
associated with a specific channel (port) or packet. The Sink control and status signals are
defined in Table 2-2.
There are six global status signals:
• Sink Out-of-Frame (SnkOof) is asserted active high whenever the core loses
synchronization with the SPI-4.2 interface.
• Sink Bus Error Status (SnkBusErrStat[7:0]) is asserted when a SPI-4.2 protocol
violation or an error not associated with a specific data packet occurs. Each bit of the
SnkBusErrStat bus corresponds to one of the following conditions:
♦ SnkBusErrStat[0]: Minimum SOP spacing was violated.
♦ SnkBusErrStat[1]: EOP control word not immediately preceded by data.
(Example: EOP followed immediately by another EOP)
♦ SnkBusErrStat[2]: Payload control word not immediately followed by data.
(Example: A payload control word is followed immediately by another payload
control word.)
♦ SnkBusErrStat[3]: DIP4 error received during idles or training patterns.
♦ SnkBusErrStat[4]: Reserved control words received.
End of Packet
(EOP, odd bytes
valid)
RDat[14:13] = 11 SnkFFEOP, SnkFFMod[1:0]
When RDat[14:13] = 11:
MOD = 11 if data bits 31–8 have valid data
MOD = 01 if data bits 31–24 have valid data
End of Packet
(EOP Abort, error
condition)
RDat[14:13] = 01 SnkFFErr & SnkFFEOP
Table 4-3: SPI-4.2 Control Word Mapping to 32-bit User Interface (Continued)
Control Word
Associated SPI-4.2
Control
Word bits on RDat
(Qualified by RCtl=1)
Associated Sink FIFO Signals