Forum Discussion
TimeQuest ALTPLL wrong setup relation
Hi,
recently I found some strange behaviour of timequest STA regarding simple design with PLL on Quartus Prime Lite. If there is simple data transfer between clock (i_CLK) and clock that's output of PLL (sys_clk) (1:1 ratio "normal" mode) from same clock, then for STA setup and hold time relationshiops are dependant on waveform (phase shift) from main clock (i_CLK) that I create.
So for example in sdc:
create_clock -name {i_CLK} -period 10.000 -waveform { 0.000 5.000 } [get_ports {i_CLK}]
derive_pll_clocks
derive_clock_uncertainty
setup is 10 ns and hold is 0 ns as expected
but for constraints
create_clock -name {i_CLK} -period 10.000 -waveform { 8.000 13.000 } [get_ports {i_CLK}]
derive_pll_clocks
derive_clock_uncertainty
setup is 3.334 ns and hold -6.636 ns
From the clock tree perspective it looks like STA takes clock edges and apply it to nearest PLL VCO edge and apply that as output waveform phase shift and this leads to unrealistic timing (?) requirements that are dependand on arbitrary waveform generation in sdc, where it shouldn't be a case.
How to handle this situation - override setup/hold with set_max/min_delay ?
Moreover in Quartus Prime Pro everythink works as exptected and relation stays always the same - ts 10.0 th 0.00
Regards
27 Replies
- toczkows
New Contributor
thanks for the reply and some solution.
Regarding Quartus Pro I'll try to add qar file @ monday as for today I don't have access for that version.
- Nurina
Regular Contributor
Hello,
Have you tried the solution?
Can you provide the .qar file for Pro?
Thanks,
Nurina
- Nurina
Regular Contributor
Hello,
I have received feedback from engineering team that the design for Pro version is not needed anymore.
Therefore since your problem has been addressed, I now transition this thread to community support. If you have a new question, please login to https://supporttickets.intel.com , view details of the desire request, and post a feed/response within the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support. The community users will be able to help you on your follow-up questions.
p/s: If any answer from community or Intel support are helpful, please feel free to mark as solution, give Kudos and rate 4/5 survey
Regards,
Nurina