User guide

Spartan-6 FPGA Configuration User Guide www.xilinx.com 127
UG380 (v2.7) October 29, 2014
Verifying Readback Data
Verifying Readback Data
The readback data stream contains configuration frame data that are preceded by one
frame of pad data, as described in the Configuration Memory Read Procedure
(SelectMAP). The readback stream does not contain any of the commands or packet
information found in the configuration bitstream and no CRC calculation is performed
during readback. The readback data stream is shown in Figure 6-3.
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 (MSK and MSD). 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. Compare readback data to the RBD golden readback file. Mask by using the MSD file (see
Figure 6-4).
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.
X-Ref Target - Figure 6-3
Figure 6-3: Readback Data Stream
Pad Frame
Type 2 -
IOB Frame Data
Pad Frame
(1 16-Bit Word)
(65 16-Bit Words)
(65 16-Bit Words)
Type 0 -
CLB Frame Data
To t al
Number of
Device
Frames
1 Frame
Readback Data
UG380_c6_03_062911
Type 1 -
Block RAM
Frame Data
Pad Frame