Forum Discussion
Occasional ContributorHow to tell Quartus my Arria10 target system CLKUSR frequency is 100MHz?
Hi Steve,
Based on the response that I provided, you need not worry about the constraint on the pin for XCVRs.
As the Quartus is assuming a 125MHz frequency, it is basically constraining it to the maximum allowed frequency for the XCVR applications. If the timing analyzer reports that 125MHz is achieved, then 100MHz will definitely work.Regards,
Aqid
Regular ContributorHi Steve,
Please refer to the following explanation of the Warning that you see.
Based on the explanation, we would infer that Quartus detected transceivers in your design.
- If transceivers are used in your design, then you need NOT do a pin assignment in the .qsf. However, it is must to provide a clock of 100-125 MHz at its input. No need to constraint it in the .sdc.
- If you are not using transceivers, not using HMC, and not using this pin as a user-supplied configuration clock, instead want to use it as a GPIO, then you need to assign the logic port to the device CLKUSR pin location and constraint the pin in .sdc.
We hope this information helps.
Regards,
Aqid
Occasional ContributorHi Aqid
Thanks -- all understood -- my purpose is to identify why timing analyser reports CLKUSR at 125MHz when our design requires 100MHz -- and if there is a method to indicate to Quartus/Platform-Designer what CLKUSR frequency actually is or failing that if the incorrect CLKUSR frequency reported is in fact unimportant and can be ignored (our project does seem to mostly run as expected but there are some quirks which could be related to transceiver operation)
Regards, Steve
- AqidAyman_Altera
Hi Steve,
Based on the response that I provided, you need not worry about the constraint on the pin for XCVRs.
As the Quartus is assuming a 125MHz frequency, it is basically constraining it to the maximum allowed frequency for the XCVR applications. If the timing analyzer reports that 125MHz is achieved, then 100MHz will definitely work.Regards,
Aqid- Steve-Mowbray-ENL
Hi Aqid
That was my hoped for situation and seems to be confirmed by seemingly normal operations on target -- my concern was 125MHz was required whereas target has 100MHz leading to possible marginal behaviour...
Regards -- Steve
