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Adventurer
Adventurer
2,555 Views
Registered: ‎10-02-2014

Multiple IDELAYCTRL per bank

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Hello  we are designing a board meant to decode 8 Open LDI video streams (https://en.wikipedia.org/wiki/OpenLDI).

Each Open LDI interface will need an iserdes macro that will require an IDELAYCTRL.

 

The FPGA that we are using is a Kintex 7 XC7K325T FFG676.

 

The board will have 4 banks dedicated to the OpenLDI decoders, but that will mean that 2 IDELAYCTRL per bank are needed.

 

Is this doable or the one and only IDELAYCTRL availiabe is the one of the bank's clock region?

 

Thanks,

 

Marco

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Historian
Historian
4,455 Views
Registered: ‎01-23-2009

Re: Multiple IDELAYCTRL per bank

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There is one and only one IDELAYCTRL per bank.

 

That being said, why do you think you need more than one IDELAYCTRL per bank? Even if there are two interfaces on a bank, and each interface needs IDELAYs, you still only need one IDELAYCTRL per bank.

 

The IDELAYCTRL merely serves to calibrate the tap delays of all the IDELAY/ODELAYs in a bank - the IDELAYCTRL needs a reference clock and a reset. The clock must be one of the legal frequencies (either 200MHz, 300MHz or 400MHz, only some of which are legal in some speed grades), and the RST is generally only needed at power up. The only time you need different IDELAYCTRLs is when the reference frequency (or RST) you are planning to use for one interface is different from what you need for another interface (which really should almost never happen).

 

Now, things get complicated if you try and use the I/O Wizard. There you start running into problems with IODELAY_GROUPs (which are really a fiction, which tell the tools which clock and RST to connect to the IDELAYCTRL in each bank based on the IODELAY_GROUP of the IDELAY/ODELAYs used in that bank). But if you manually instantiate everything you should have no problems.

 

Avrum

2 Replies
Highlighted
Historian
Historian
4,456 Views
Registered: ‎01-23-2009

Re: Multiple IDELAYCTRL per bank

Jump to solution

There is one and only one IDELAYCTRL per bank.

 

That being said, why do you think you need more than one IDELAYCTRL per bank? Even if there are two interfaces on a bank, and each interface needs IDELAYs, you still only need one IDELAYCTRL per bank.

 

The IDELAYCTRL merely serves to calibrate the tap delays of all the IDELAY/ODELAYs in a bank - the IDELAYCTRL needs a reference clock and a reset. The clock must be one of the legal frequencies (either 200MHz, 300MHz or 400MHz, only some of which are legal in some speed grades), and the RST is generally only needed at power up. The only time you need different IDELAYCTRLs is when the reference frequency (or RST) you are planning to use for one interface is different from what you need for another interface (which really should almost never happen).

 

Now, things get complicated if you try and use the I/O Wizard. There you start running into problems with IODELAY_GROUPs (which are really a fiction, which tell the tools which clock and RST to connect to the IDELAYCTRL in each bank based on the IODELAY_GROUP of the IDELAY/ODELAYs used in that bank). But if you manually instantiate everything you should have no problems.

 

Avrum

Adventurer
Adventurer
2,536 Views
Registered: ‎10-02-2014

Re: Multiple IDELAYCTRL per bank

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Driving home I was thinking about the same thing... but you will get full credit for the solution :D.

Give me some time to try it out.

 

Thanks a lot,

 

Marco

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