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Platform Flash In-System Programmable Configuration PROMs
Additional Features for the XCFxxP
SelectMAP (parallel) configuration modes are supported for
FPGA configuration when using a XCFxxP PROM
programmed with a compressed bitstream. Compression
rates vary depending on several factors, including the target
device family and the target design contents.
Internal Oscillator
The 8/16/32 Mb XCFxxP Platform Flash PROMs include an
optional internal oscillator which can be used to drive the
CLKOUT and DATA pins on FPGA configuration interface.
The internal oscillator can be enabled when programming
the PROM, and the oscillator can be set to either the default
frequency or to a slower frequency. Refer to the “XCFxxP
Decompression and Clock Options” chapter of UG161,
Platform Flash PROM User Guide, for internal oscillator
recommendations.
The decompression option is enabled during the PROM
programming sequence. The PROM decompresses the
stored data before driving both clock and data onto the
FPGA's configuration interface. If Decompression is
enabled, then the Platform Flash clock output pin
(CLKOUT) must be used as the clock signal for the
configuration interface, driving the target FPGA's
configuration clock input pin (CCLK). Either the PROM's
CLK input pin or the internal oscillator must be selected as
the source for CLKOUT. Any target FPGA connected to the
PROM must operate as slave in the configuration chain,
with the configuration mode set to Slave Serial mode or
Slave SelectMap (parallel) mode.
CLKOUT
The 8/16/32 Mb XCFxxP Platform Flash PROMs include the
programmable option to enable the CLKOUT signal which
allows the PROM to provide a source synchronous clock
aligned to the data on the configuration interface. The
CLKOUT signal is derived from one of two clock sources: the
CLK input pin or the internal oscillator. The input clock source
is selected during the PROM programming sequence. Output
data is available on the rising edge of CLKOUT.
When decompression is enabled, the CLKOUT signal
becomes a controlled clock output with a reduced maximum
frequency. When decompressed data is not ready, the
CLKOUT pin is put into a high-Z state and must be pulled
High externally to provide a known state.
The CLKOUT signal is enabled during programming, and is
active when CE is Low and OE/RESET is High. On CE
rising edge transition, if OE/RESET is High and the PROM
terminal count has not been reached, then CLKOUT
remains active for an additional eights clock cycles before
being disabled. On a OE/RESET falling edge transition,
CLKOUT is immediately disabled. When disabled, the
CLKOUT pin is put into a high-impedance state and should
be pulled High externally to provide a known state.
The BUSY input is automatically disabled when
decompression is enabled.
See the "Decompression Setups" section in the Platform
Flash PROM User Guide for setup details.
Design Revisioning
When cascading Platform Flash PROMs with CLKOUT
enabled, after completing it's data transfer, the first PROM
disables CLKOUT and drives the CEO pin enabling the next
PROM in the PROM chain. The next PROM begins driving
the CLKOUT signal once that PROM is enabled and data is
available for transfer.
Design Revisioning allows the user to create up to four
unique design revisions on a single PROM or stored across
multiple cascaded PROMs. Design Revisioning is supported
for the 8/16/32 Mb XCFxxP Platform Flash PROMs in both
serial and parallel modes. Design Revisioning can be used
with compressed PROM files, and also when the CLKOUT
feature is enabled. The PROM programming files along with
the revision information files (.cfi) are created using the
iMPACT software. The .cfi file is required to enable design
revision programming in iMPACT.
During high-speed parallel configuration without
compression, the FPGA drives the BUSY signal on the
configuration interface. When BUSY is asserted High, the
PROMs internal address counter stops incrementing, and
the current data value is held on the data outputs. While
BUSY is High, the PROM continues driving the CLKOUT
signal to the FPGA, clocking the FPGA’s configuration logic.
When the FPGA deasserts BUSY, indicating that it is ready
to receive additional configuration data, the PROM begins
driving new data onto the configuration interface.
A single design revision is composed of from 1 to n 8 Mb
memory blocks. If a single design revision contains less
than 8 Mb of data, then the remaining space is padded with
all ones. A larger design revision can span several 8 Mb
memory blocks, and any space remaining in the last 8 Mb
memory block is padded with all ones.
•
A single 32 Mb PROM contains four 8 Mb memory
blocks, and can therefore store up to four separate
design revisions: one 32 Mb design revision, two 16 Mb
design revisions, three 8 Mb design revisions, four
8 Mb design revisions, and so on.
Decompression
The 8/16/32 Mb XCFxxP Platform Flash PROMs include a
built-in data decompressor compatible with Xilinx advanced
compression technology. Compressed Platform Flash
PROM files are created from the target FPGA bitstream(s)
using the iMPACT software. Only Slave Serial and Slave
DS123 (v2.18) May 19, 2010
www.xilinx.com
Product Specification
8
XILINX [ XILINX, INC ]
