Reconstructing source code from JED file

[Kresten Nřrgaard]

Hi

Im upgrading an old HW-design for a client, which includes and Xilinx
XC9536XL. Unfortunately he only seems to have the .JED file, which gives me
a hard time figuring out how the constuction was intended to work.

I wonder if there is a simple way to reconstruct the boolean equations from
the JED file?

Kresten

 

[Jim Granville]

"Kresten Nřrgaard" wrote

Hi

Im upgrading an old HW-design for a client, which includes and Xilinx
XC9536XL. Unfortunately he only seems to have the .JED file, which gives
me
a hard time figuring out how the constuction was intended to work.

I wonder if there is a simple way to reconstruct the boolean equations
from
the JED file?

For some PLDs there are JED2EQN pathways - ask Xilinx ?.
Where this does not exist, you have some choices
a) reverse engineer the JED - not impossible, but will require many
iterations
and a good understanding of the CPLD structure to get the info.
Creating simple testcase templates with the tools helps identify the fuse
pattern areas.

Likely to be more productive to 'have a really good look for the source'

b) Reverse engineer the function.
They _should_ have a schematic, and info of things like memory or IO
mappings.
You can also generate JED test vectors, and use these to exercise the
existing device, and confirm the new one is functionally identical.

Be aware that because of the internal AND.OR structure, you
can create two JEDs functionally identical, but that fail a compare.

-jg