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delay part of a clock cycle

Altera_Forum
Honored Contributor II
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Hello 

i have a question is how to generate a delay for part of a clock cycle (for example after 0.1 of the clock cycle), since I couldn't use the wait for command for synthesis 

is there any way to do that in VHDL inside a process 

 

for example  

i want to make  

a <= b; but after 0.1 of the clock cycle passed, not exactly at the rising edge 

 

please if any one can help 

 

 

 

 

 

 

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Altera_Forum
Honored Contributor II
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You could use a PLL to generate a phase-shifted version of your clock then pass data between the clock domains, but with a phase shift of only 10% of the clock period it may be tough to meet the setup time of the second register depending on your clock frequency. A 10x clock (also generated using a PLL) would be another option. Without more information on what you're trying to do and how fast you're running that's the best I got.

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Altera_Forum
Honored Contributor II
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What is the point of delay? 

The fitter will insert delay from clk edge out of control as long as it passes timing. The whole idea of clk is to sample at its edge.
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Altera_Forum
Honored Contributor II
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Hi Mr. kaz 

thank you for your reply  

the idea is that i have two signal from two process  

and i used them in a third process  

but these two signal arrive after some part of the clock cycle 

so i want to delay the action to some percent of the clock cycle (after 10% of the rising edge)
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Altera_Forum
Honored Contributor II
729 Views

 

--- Quote Start ---  

Hi Mr. kaz 

thank you for your reply  

the idea is that i have two signal from two process  

and i used them in a third process  

but these two signal arrive after some part of the clock cycle 

so i want to delay the action to some percent of the clock cycle (after 10% of the rising edge) 

--- Quote End ---  

 

 

you sample each of two signals on same one clk edge and sample result on next edge of same clk. All fpga design is based on sampling on clk edge and expecting decision to arrive at next clk edge. Inserting micro delays is not possible in current technology of FPGAs.
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