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5887 Discussions

Parallel Flash Loader (PFL) IP Core Timing Constrains

Altera_Forum
Honored Contributor II
1,353 Views

Hallo Everyone 

 

I am making a Parallel Flash Loader (PFL) IP core for MAX V device. I have some problems in constraining the design with the timing. In the following link it is mentioned that 

 

https://www.altera.com/documentation/sss1411439280066.html#sss1458191622012 

 

the following paths should be set as False Path 

 

pfl_flash_access_request 

flash_nce 

flash_noe 

flash_nwe 

flash_data 

flash_addr 

 

but when i set them as false path, the design is not fully constrained. The time quest analyzer shows that this parts are partly constrained and suggest to add an output delay. I wrote the SDC file in the attachment. Can any one give me any suggestion or solutions on what might be wrong here or if my SDC file is correct?
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4 Replies
Altera_Forum
Honored Contributor II
76 Views

What path(s) does the timing analyzer say are considered unconstrained? There's no way to tell what's wrong by looking at just the .sdc file.

Altera_Forum
Honored Contributor II
76 Views

Hallo sstrell 

 

Thanks for your reply. For Example if set the flash_nce path as false path, as suggested in the pfl user guide, on the time constrains report it shows that flash_nce path is partially constrained. I am attaching the screen shots of the timing analyzer report that i get when i set the flash_nce as a false path. Setting the other paths mentioned in first post also produces same kind of behavior. I am also attaching the report from the timing analyzer. You can open the file with notepad.  

 

Let me know if this information is enough for you, to find the problem or you need some more information.
Altera_Forum
Honored Contributor II
76 Views

I don't understand why you're doing this: 

 

set_false_path -from [get_clocks *] -to [get_ports {flash_nce}] 

 

It should be simply: 

 

set_false_path -to [get_ports {flash_nce}] 

 

Same with all your output false paths.
Altera_Forum
Honored Contributor II
76 Views

thanks a lot for your reply. This solves the problem. So if i understood you correctly  

 

output false paths should be set with the command set_false_path -to 

input false paths should be set with the command set_false_path -from 

 

I tried this two command on my input and output ports false paths and it works.
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