Xilinx 8.2i manual Bd Update Block Rams, Do Not Run DRC, Set Configuration, BitGen Options

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BitGen Options

The rawbits file consists of ASCII ones and zeros representing the data in the bitstream file. If you are using a microprocessor to configure a single FPGA, you can include the rawbits file in the source code as a text file to represent the configuration data. The sequence of characters in the rawbits file is the same as the sequence of bits written into the FPGA.

–bd (Update Block Rams)

–bdfile_name

The –bd option updates the bitstream with the block ram content from the specified ELF or MEM file. See Chapter 24, “Data2MEM” for more information.

–d (Do Not Run DRC)

Do not run DRC (design rule check). Without the –d option, BitGen runs a DRC and saves the DRC results in two output files: the BitGen report file (file_name.bgn) and the DRC file (file_name.drc). If you enter the –d option, no DRC information appears in the report file and no DRC file is produced.

Running DRC before a bitstream is produced detects any errors that could cause the FPGA to malfunction. If DRC does not detect any errors, BitGen produces a bitstream file (unless you use the –j option described in “–j (No BIT File)”).

–f (Execute Commands File)

–fcommand_file

The –f option executes the command line arguments in the specified command_file. For more information on the –f option, see “–f (Execute Commands File)” in Chapter 1.

–g (Set Configuration)

The –g option specifies the startup timing and other bitstream options for Xilinx FPGAs. The debug bitstream can only be used for master and slave serial configurations. It is not valid for Boundary Scan or Slave Parallel/Select MAP. The settings for the –g option depend on the architecture of the design. These settings are described in the following section:

–g (Set Configuration—Virtex/-E/-II/-II Pro/-4 and Spartan-II/-IIE/-3/-3E)

The –g option has sub-options that represent settings you use to set the configuration for a Virtex/-E/-II/-II Pro or Spartan-II/-IIE/3 design. These options have the following syntax:

bitgen –goption:setting design.ncd design.bit design.pcf

For example, to enable Readback, use the following syntax:

bitgen –g Readback

The following sections describe the options and settings for the –g option. Each –g option is listed with supported architectures, settings, and defaults.

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