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21615 Discussions

Understand and solve setup violation in dual domain clock

Altera_Forum
Honored Contributor II
1,467 Views

Hello all, 

 

I have a project where I have two clock:  

- 50 MHz oscillator for NIOS synthetized on FPGA  

- 60 MHz oscillator for USB (from UM232H module) used in a custom component attached wtih QSys to NIOS 

 

QSys automatically handle cross-domain transfers of signals. 

 

I wat to see signals that come and go into USB module with signaltap so I have multiplied by 2 (to 120 MHz) USB clock with a PLL and attached it to SignalTap. 

 

Timing requirements are not met because I have ADBUS signals (bidirectional DATA signals for USB) that violate setup timing by -0.684ns 

If I report Timing Closure Reccomendations with TimeQuest I get: 

 

 

--- Quote Start ---  

Register the partition boundaries for the path from pin_ft232h_ADBUS[5] to sld_signaltap:aut...rigger_in_reg[5] 

Issue: Cross-partition Paths 

From: pin_ft232h_ADBUS[5] 

To: sld_signaltap:auto_signaltap_0|acq_trigger_in_reg[5] 

TimeQuest analysis: report timing 

Partitions that should be merged: 

Top -> sld_signaltap:auto_signaltap_0 

 

--- Quote End ---  

 

 

What can I do? Attached Timequest details
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Altera_Forum
Honored Contributor II
709 Views

Deleting ADBUS from signaltap seem to remove violation. Are so hard to observe bidirectional pin?

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