User guide

Spartan-6 FPGA Configuration User Guide www.xilinx.com 77
UG380 (v2.7) October 29, 2014
Generating PROM Files
in x16 mode. The FPGA now knows on which bus width to receive the rest of the data. No
packet processed by the FPGA until the Sync word is found. See Table 5-7.
Generating PROM Files
PROM files are generated from bitstream files with the PROMGen utility. Users can access
PROMGen directly from the command line or indirectly through the iMPACT File
Generation Mode. For PROMGen syntax, refer to UG628
, Command Line Tools User Guide.
For information on iMPACT software, refer to the ISE® software documentation. PROM
files serve to reformat bitstream files for PROM programming and combine bitstream files
for serial daisy-chains (see PROM Files for Serial Daisy-Chains).
PROM Files for Serial Daisy-Chains
Configuration data for serial daisy-chains requires special formatting because separate
BIT files cannot simply be concatenated together to program the daisy-chain. The special
formatting is performed by PROMGen (or iMPACT software) when generating a PROM
file from multiple bitstreams. To generate the PROM file, specify multiple bitstreams using
the PROMGen -n, -u, and -d options or the iMPACT Software File Generation Wizard.
Refer to ISE software documentation for details.
PROMGen reformats the configuration bitstreams by nesting downstream configuration
data into configuration packets for upstream devices. Attempting to program the chain by
sending multiple bitstreams to the first device causes the first device to configure and then
ignore the subsequent data.
PROM Files for SelectMAP Configuration
The MCS file format is most commonly used to program Xilinx® configuration PROMs
that in turn program a single FPGA in SelectMAP mode. For custom configuration
solutions, the BIN and HEX files are the easiest PROM file formats to use due to their raw
data format. In some cases, additional formatting is required; refer to XAPP502
, Using a
Microprocessor to Configure Xilinx FPGAs via Slave Serial or SelectMAP Mode for details.
If multiple configuration bitstreams for a SelectMAP configuration reside on a single
memory device, the bitstreams must not be combined into a serial daisy-chain PROM file.
Instead, the target memory device should be programmed with multiple BIN or HEX files.
If a single PROM file with multiple, separate data streams is needed, one can be generated
in iMPACT software by targeting a Parallel PROM, then selecting the appropriate number
of data streams. This can also be accomplished through the PROMGen command line.
Refer to PROMGen software documentation for details.
PROM Files for SPI/BPI Configuration
The -d, -u, -spi, -s, and -data_width options in PROMGen or the iMPACT Software
File Generation Wizard are used to create PROM files for third-party flash devices. The
output format supported by the third-party programmer is important. Some BPI devices
require endian-swapping to be enabled when programming the PROM file. Refer to the
flash vendor's documentation.
Table 5-7: Sync Word
31:24 23:16 15:8 7:0
0xAA 0x99 0x55 0x66