ISE
Readback Options
The following Readback properties are available for the Generate Programming File process for FPGA devices. Readback is the process of reading back data from the FPGA device to verify that the design was downloaded properly.
  •  Security
    Specifies the design security by selecting whether or not to allow the readback and reconfiguration of the device. After the FPGA design has been configured, the FPGA configuration data can be read back and compared with the original configuration data. Also, the device can be reconfigured with a different bitstream. For increased design security, select either Disable Readback or Disable Readback and Reconfiguration. Select a Readback option from the drop-down list.
    •  Enable Readback and Reconfiguration
      Enables the readback and reconfiguration of data.
    •  Disable Readback
      Disables readback. Use this option for design security. By disabling readback, configuration data is secure from being read from the FPGA.
    •  Disable Readback and Reconfiguration
      Disables both readback and reconfiguration. Use this option for design security. By disabling readback and reconfiguration, configuration and reconfiguration data is secure from being read from the FPGA.
    By default, this property is set to Enable Readback and Reconfiguration.
  •  Create Readback Data Files
    Specifies whether or not to create readback data files. The readback files represent the bitstream necessary to perform readback. The following files are created:
    •  RBA file – an ASCII file that contains readback commands.
      Note To create this file, you must enable the Create ASCII Configuration File property in the General Options dialog box.
    •  RBB file – a binary file that contains readback commands.
    •  RBD file – an ASCII file that contains only expected readback data, including pad words and frames. No commands are included.
    •  MSD file – an ASCII file that contains only mask information for verification, including pad words and frames. No commands are included.
    By default, this property is set to False (checkbox is blank), and the readback data files are not generated.
  •  Allow SelectMAP Pins to Persist
    Note The Allow SelectMAP Pins to Persist property is only available when the Create Readback Data Files property is set to True (checkbox is checked).
    When this property is set to True (checkbox is checked), the SelectMAP pins on the device persist as configuration pins after configuration is completed, and the verify operation uses these pins to read back the data, if the mode pins are set to SelectMAP. When this property is set to False (checkbox is blank), the SelectMAP pins only function as configuration pins during the configuration process, and become User-I/O after configuration completes.
    By default, this property is set to False (checkbox is blank).
  •  Create Logic Allocation File
    Note The Create Logic Allocation Files property is only available when the Create Readback Data Files property is set to True (checkbox is checked).
    Specifies whether or not to create a logic allocation file (design_name.ll) for your design. The logic allocation file indicates the bitstream position of latches, flip-flops, IOB inputs and outputs, and the bitstream position of LUT programming and BlockRAMs. The iMPACT tool uses the design_name.ll file to locate signal values inside a readback bitstream.
    By default, this property is set to False (checkbox is blank), and this file is not created.
  •  Create Mask File
    Note The Create Mask File property is only available when the Create Readback Data Files property is set to True (checkbox is checked).
    Specifies whether or not to create a mask file (design_name.msk). The mask file is used to determine which bits in the bitstream should be compared to readback data for verification purposes.
    By default, the property is set to False (checkbox is blank), and a mask file is not created.

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