Modifying FPGA Bitstreams

[viScience]

Would like to know if anyone has attempted to modify FPGA bitstreams using Xilinx JBITS or similar tools.  The appeal here is that one could

do things like create asynchronous logic and point to point ARC's between FPGA I/O pins.

[Doug-B]

Hey sachsm,

By bitstream, do you mean the actual bit file that is compiled onto the FPGA? I am not familiar with the Xilinx JBITS so I am not sure what modifications with this tool would look like and how that would affect the bit file once it is compiled to the FPGA. If you could give me a bit more information about JBITS and what it actually does I might be able to provide a better answer.

Thanks,

Doug B

[viScience]

Yes, the actual FPGA bitstream.  JBITS is a JAVA API for building tools to allow modification of a compiled FPGA by directly interpreting and modifying the bitstream.

I have attached a short article on the JBITS API.  In addition to being able to produce asynchronous logic you can also create direct ARC's between IO pins.

[Doug-B]

Hey sachsm,

When LabVIEW compiles a bit file to a FPGA, it creates a .lvbitx file rather than just a regular .bit file. The .lvbitx file is encrypted and because of this I doubt that the JBITS program would be able to reliably modify the file as you would like. Additionally, since the developers of our FPGA software decided to encrypt the bit file it seems to me like they are trying to protect against allowing the bit file to be modified by outside sources.

Hope This Helps,

Doug B