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How to make time constraint in Quartus?

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pwq1999

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i write code to read flash with a spi port. i use signalTap II, and now i encount an problem.
when i change some signals in signaltap II, and synthesis again, with no change of my design code,but sometimes data can be read right, sometimes read wrong. and in signaltap II, i can see that after each synthesis, the delay time of signal from flash is variable,i mean not a constant time,and i don't know how to do it!

can anyone help me out?
thanks in advance!
 

Re: timing constraint

Have you given the right time constraint?
Mybe you've timing error and for that reason you see sometimes bad results and other good one.

I'm aware that you're looking the signals into the signal tap with the same clock you're generating it, right?
 

timing constraint

maybe the signals coming from the flash i want to view have a delay, and i don't know how to do time constraint. i want no delay or less delay when the signal comes out the flash and into fpga.
i use pll to generate a 2x clock,and use it to sample data i want to view in signal tapII.

thanks for reply! and can you give me a suggestion how to make time constraint in quartus 2.
 

Re: timing constraint

how to make time constraint in qu(at)rtus
Click to expand...
1. open 'Compilation Report', go to the
Fitter->Resource Section->Input Pins
right click on the pin you want to control its delay
and choose Locate in Timing Closure Floorplan;
then you can manually place [drag&drop] the input signal
destination LAB somewhere near the pin to have as short
delay as possible;
quartus will save the placement in *.qsf file;

OR:

2.click on 'Assignment Editor', on the top field choose
Timing->tpd;
in the 'From' field put your input signal(s)
[wild card '*' allowed] in a 'Value' field type required delay
[ 1, 1.2 ns sounds good], save, recompile;
check your *.qsf file, the quartus settings file to see
how you can do it in any text editor latter on;
good luck;
 

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    pwq1999

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timing constraint

thank you very much, i do as what you have described, and now i can see it.
thanks again!
 

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