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14968 Discussions

Recommended procedure for FPGA clock forwarding

SKon1
Novice
533 Views

Hello,

 

I have an FPGA clock coming into my design.

I want to simply send this clock using another pin.

 

From working with other vendors - I learned that the recommended practice is to use an Output DDR Flip Flop for that purpose - as described in this link :

https://forums.xilinx.com/t5/Timing-Analysis/Why-ODDR-for-forwarded-clock/td-p/756737

 

Is this also the recommended practice for Intel FPGAs ?

 

0 Kudos
11 Replies
Rahul_S_Intel1
Employee
430 Views

Hi ,

In my point of view it depends upon your use case, if you want simple to give to an I/O pin you can directly hoke it up in RTL code and send the clock .

 

But if you need to route the clock in to global or any type of clock path, I will recommend to use the AltCLKCTRL ( alt clock control path) IP before giving to out put pin.

 

SKon1
Novice
430 Views

Hi,

Is there an official Intel document that recommends ALTCLKCTRL for clock forwarding ?

Rahul_S_Intel1
Employee
430 Views
SKon1
Novice
430 Views

Hi,

I've read this document.

But couldn't find where it suggests to use the ALTCLKCTRL for the purpose of forwarding the clock as I asked.

If this recommendation exists in the document - please point me to it.

 

 

SKon1
Novice
430 Views

This is such a simple request - I really don't understand why no one can provide a definitive answer to it !

I'll ask again.

Please point me to an official Intel document that states the RECOMMENDED procedure for forwarding a clock to an output pin.

Rahul_S_Intel1
Employee
430 Views

Hi ,

May I know what device is it been using , i will send u the official document wiith respect to that device

SKon1
Novice
430 Views

Arria V

Rahul_S_Intel1
Employee
430 Views

Hi,

Kindly find the below document for your reference .

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/arria-v/av_5v2.pdf#page=...

Page no: 102

 

Note:

These are the two documents in which Intel recommends the use of altclkctrl block .

 

 

 

SKon1
Novice
430 Views

Hi,

I'm reading page 102.

It shows an option to use the ALTCLKCTRL block for clock muxing.

But I don't require clock muxing - so my question remains unanswered...

 

I have a SINGLE clock that's coming into an FPGA pin - I'm requirement to send it to an output pin.

What's the recommended procedure for that ?

 

Rahul_S_Intel1
Employee
430 Views

Hi ,

Altclkctrl is the best approach and the above two documents are the only reference we have for your query .

I want to set the expectation that , I could not able to provide any more further details or writing other than the above document , apology to say that.

 

Rahul_S_Intel1
Employee
430 Views

Hi ,

Let me know if you need further assitance

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