06-10-2014 04:27 AM
How many dummy words are available before the sync word in Spartan 6 configuration file(.bin or .bit).
In UG380(ver 2.5) page 106, it is given as sixteen dummy words(0xFFFF) for BPI address cycle. But in the bin file generated for Spartan 6 LX 45, LX 150 contain 8 words (each 0xFFFF). So which one is correct? How many dummy words are required between the sync word 0xAA99 0x5566 for Spartan 6 device?
06-10-2014 04:32 AM - edited 06-10-2014 04:40 AM
the number of Dummy words before the sync word is not a problem.
You can add the dummy words before the sync word if you need to setup the configuration.
Configuration begins only after the sync word is detected.
06-10-2014 09:07 PM
As discussed, the configuration starts only after SYNC word shows up in bitstream.
However try to change the BPI device selection in the IMPACT GUI (select the largest capacity BPI device) and see if that changes the number of dummy words.
06-11-2014 01:21 AM
We are using ISE 13.4 for th generating bin file for Spartan 6 LX 45 device. I wanted to know the exact number of dummy words that are available in the bin file generated. Does this vary with the tools or any bit gen settings.
This information is needed since we had to define some fixed pattern in the software to identify the FPGA confgiuration file. I could see dummy words(0xFFFF 8 times) and sync word(0xAA99 0x5566) at the beginning of the .bin file repeatedly for all the bin files generated. But the number of dummy words is not mentioned properly in any of the data sheets. Can you please let me in which document information about the number of dummy words generated from the ISE13.4 tool for Spartn 6 device(specifically LX 45) is available?
06-11-2014 02:47 AM
To add more information the UG380 snapshot(dummy_words_ug_380.jpg) is given here which says about the dummy word of 0xFFFF is generated in the Spartan6 bitstream.
And the snapshot of the bin file(bin_file.jpg) generated for the Spartan 6 device is also attched. THis contains 0xFFFF 8 times . could please let me know the docuemnt where the number of dummy words generated from the ISE13.4 tool is defined properly.
06-11-2014 06:21 AM
the bin/mcs file generated has 8 dummy words, you can provide this info to your software. This is same in 14.7 generated tool as well.
The dummy words "FF" provided in the bin file gives time for the initialization of the FPGA before it starts the configuration when the sync word is seen.
As said earlier you can add some more dummy words if see any issues in starting of the configuration.
If your sfotware is ready and the board you can test with the defualt dummy words(8) generated in the bin file.
06-12-2014 05:56 AM
No, the dummy words added by the 13.4 tool is not documented however this should not vary in this tool version for any of the designs bin files generated.
06-12-2014 11:40 PM
Thanks for the information. I have one more query. Whether the number of dummy words generated by 13.4 tool vary with any of the bitgen settings or it is always the same for any of the bitgen settings?
06-12-2014 11:41 PM