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R
The readback data stream is verified by comparing it to the original configuration frame
data that were programmed into the device. Certain bits within the readback data stream
must not be compared, because these can correspond to user memory or null memory
locations. The location of don't care bits in the readback data stream is given by the mask
files, the .msk and .msd files. These files have different formats although both convey
essentially the same information. Once readback data have been obtained from the device,
either of the following comparison procedures can be used:
1.
2.
Virtex-4 FPGA Configuration User Guide
UG071 (v1.12) June 2, 2017
Compare readback data to the .rbd golden readback file. Mask by using the .msd file.
The simplest way to verify the readback data stream is to compare it to the .rbd golden
readback file, masking readback bits with the .msd file. This approach is simple
because there is a 1:1 correspondence between the start of the readback data stream
and the start of the .rbd and .msd files, making the task of aligning readback, mask,
and expected data easier.
The .rbd and .msd files contain an ASCII representation of the readback and mask
data along with a file header that lists the file name, etc. This header information
should be ignored or deleted. The ASCII 1s and 0s in the .rbd and .msd files
correspond to the binary readback data from the device. Take care to interpret these
files as text, not binary sources. Users can convert the .rbd and .msd files to a binary
format using a script or text editor, to simplify the verify procedure for some systems
and to reduce the size of the files by a factor of eight.
Readback
Data Stream
Pad Frame
1 frame
Total
number
Frame Data
device
frames
Figure 8-5: Comparing Readback Data Using the .msd and .rbd Files
The drawback to this approach is that in addition to storing the initial configuration
bitstream and the .msd file, the golden .rbd file must be stored somewhere, increasing
the overall storage requirement.
Compare readback data to the configuration .bit file, mask using the .msk file.
Another approach for verifying readback data is to compare the readback data stream
to the frame data within the FDRI write in the original configuration bitstream,
masking readback bits with the .msk file.
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Verifying Readback Data
.rbd
.msd
File
File
File Header
File Header
Pad Frame
Pad Frame
Frame Data
Frame Data
Mask
UG071_52_073007
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