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38 www.xilinx.com SPI-4.2 Lite v4.3 User Guide
UG181 June 27, 2008
Chapter 2: Core Architecture
R
Note that there are legal values for each of the signals. If the configuration signal is set to an
illegal number, the core automatically sets it to the minimum value. Table 2-15 defines the
Source Static Configuration signals.
Table 2-15: Source Static Configuration Signals
Name Direction Range Description
SrcBurstMode Static Input 0 or 1 Source Burst Mode: When SrcBurstMode is set to zero,
the Source core transmits data in the FIFO if the data in
the FIFO is terminated by an EOP or if there is a
complete credit of data.
When SrcBurstMode is set to1, the Source core only
transmits data that is terminated by an EOP or when
there is data in the FIFO equal to the maximum burst
length defined by SrcBurstLen.
SrcBurstLen[5:0] Input 1-63
Values equal to 0 are set
to 1.
Source Burst Length: The Source core automatically
segments packets larger than this parameter into
multiple bursts, which are each SrcBurstLen in length.
This parameter is defined in credits (16 bytes).
The core implements this parameter as a static register
synchronous to SrcFFClk, and it can be updated in
circuit by first deasserting SrcEn.
SrcAFThresAssert[8:0] Static Input If SrcBurstMode = 0
1 to 508
Values less than 1 are set
to 1.
Values greater than 508
are set to 508.
If SrcBurstMode = 1
SrcBurstLen to 508.
Values less than
SrcBurstLen are set to
SrcBurstLen.
Values greater than 508
are set to 508.
Source Almost Full Threshold Assert: The
SrcAFThresAssert parameter specifies the minimum
number of empty FIFO locations that exist in the Source
FIFO before the Almost Full signal (SrcFFAlmostFull_n)
is asserted.
If SrcBurstMode=0, then SrcAFThresNegate is greater
than or equal to SrcAFThresAssert.
If SrcBurstMode=1, then:
(1) SrcAFThresNegate is greater than or equal to
SrcAFThresAssert
(2) SrcAFThresNegate and SrcAFThresAssert are
greater than or equal to SrcBurstLen
SrcAFThresNegate[8:0] Static Input SrcAFThresAssert to
508
Values less than
SrcAFThresAssert are
set to
SrcAFThresAssert.
Values greater than 508
are set to 508.
Source Almost Full Threshold Negate: The
SrcAFThresNegate parameter specifies the minimum
number of empty FIFO locations that exist in the Source
FIFO before the Almost Full signal (SrcFFAlmostFull_n)
is deasserted.
If SrcBurstMode=0, then:
SrcAFThresNegate is greater than or equal to
SrcAFThresAssert.
If SrcBurstMode=1, then:
(1) SrcAFThresNegate is greater than or equal to
SrcAFThresAssert
(2) SrcAFThresNegate and SrcAFThresAssert are
greater than or equal to SrcBurstLen