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Observer arablu_m
Observer
1,642 Views
Registered: ‎07-05-2018

External Clock FPGA

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Hello,

I am very new to FPGA world. Need a platform to extract signals from harmonics of a 50 kHz signal. In fact, what I am looking for is an FPGA module with at least two ADCs so that I can transfer my detected signal into the FPGA and execute a discrete Fourier transform on it. I need at least 800 ksample/s speed, enough slices on the FPGA microchip for developing the program, and the FPGA should be synchronizable into a PRS10 rubidium clock. 

I already have an NI PXIe-1073 that has a PXI-7851R IO on it. This module does not provide external clocking and the FPGA chip on it does not have enough space for developing the program that I want. Anything that has twice the space of Vertex-5 will be perfect.

 

Any suggestion is greatly appreciated. 

 

Thanks,

Masoud

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Highlighted
1,787 Views
Registered: ‎01-22-2015

Re: External Clock FPGA

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Masoud,

 

I’m glad the information was helpful.

 

Before deciding on a 7-Series FPGA, please read about the other FPGA types offered by Xilinx. These are the UltraSCALE series (faster, lower power) and Zynq-SoC (FPGA + embedded processor).  A good place to start your reading is <this> page.

 

However, based on what you’ve said, I personally feel that the 7-Series would be a good fit.   Xilinx quarterly reports have often said that the 7-Series is a very successful product.  It is still listed as an “Advanced Product” which hopefully means it will be around for a while.  How long?  Well, <this> post says that “popular part/packages have been sold for more than 15 years in some cases, even longer.”  The 7-Series FPGAs came out in 2010.

 

Another decision to make is whether you plan to purchase (at ~$3K/yr) the Vivado software/support or go with the free-of-charge Vivado WebPACK software (and no support except via this Forum).

 

Now to your questions.

 

  1. Is this chip available in the form of an evaluation board so that I can easily implement my code on it just by connecting the signal into the right input pins and also a usb or other inputs for programming?

If you decide to purchase Vivado (and yearly support for Vivado), then you have many boards to choose from.  However, if you plan to use Vivado WebPACK then you should select a board that has an FPGA that is supported by WebPACK (see Table 2-1 in UG973).

 

You can buy boards from Xilinx with FPGAs that are not supported by WebPACK and (I think) they come with a working-version of Vivado that is locked to the board.   However, when you later make your own board with the same FPGA then you will (I think) need to purchase Vivado.  See <this> post for more information.  

 

You can start your board search <here>.  If you have decided to go with the 7-Series then click on “Browse by Device Family” and select either Virtex-7, Kintex-7, or Artix-7.  I do not recommend the Spartan-7 as this is different and older technology.  For example, I note that all the Kintex-7 boards offered by Xilinx use the XC7K325T FPGA which is not supported by WebPACK.   However, you might check the “MIAMI Kintex 7 160T” shown <here> which seems to use the XC7K160T that is supported by WebPACK.

 

2 - Does these evaluation boards provide external clocking option or not?

 

I think you will find that many boards provide this option. However, be aware that this external clock is for the FPGA logic and is not the main clock for the XADC digitizer.  The sampling rate (ie. main clock) for the XADC can be configured in software and has a range of about 100-1000 KSPS.

 

-best of luck,

Mark

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6 Replies
1,576 Views
Registered: ‎01-22-2015

Re: External Clock FPGA

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Hi Masoud,

 

Welcome to the Xilinx Forum!

 

I see from the data sheet found <here> for PXI-7851R that this board has a Virtex-5 LX30 with the following specifications:

19200 LUTs, 19200 FF, 32 DSP48, 1152Kb BRAM

 

Many of the newer 7-Series FPGAs from Xilinx have the extra space (2x) that you want. For example, the Kintex-7 (xc7k160t) has the following specifications:

101400 LUTs, 202800 FF, 600 DSP48, 11700Kb BRAM

 

The xc7k160t is further described by Xilinx documents DS180 and DS182.  You will also find that this FPGA has a built-in digitizer called the XADC that is described by Xilinx document UG480.  The XADC is 16-bit (12-bit effective) and can simultaneously sample two analog inputs at rates up to 1000 ksps.

 

Finally, you can develop your program (HDL) for the xc7k160t using the Vivado Webpack software found <here> that is provided free-of-charge from Xilinx.

 

Mark

 

 

 

 

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Observer arablu_m
Observer
1,517 Views
Registered: ‎07-05-2018

Re: External Clock FPGA

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Thank you Mark. Looking into this FPGA chip features, it looks promising. However, I have two more questions:

 

1- Is this chip available in the form of an evaluation board so that I can easily implement my code on it just by connecting the signal into the right input pins and also a usb or other inputs for programming? If so, please share the link with me because I searched a lot and found some suppliers that I am not sure their product is an evaluation board or the microchip alone.

 

2- Does these evaluation boards provide external clocking option or not?

 

Thanks,

Masoud

 

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Highlighted
1,788 Views
Registered: ‎01-22-2015

Re: External Clock FPGA

Jump to solution

Masoud,

 

I’m glad the information was helpful.

 

Before deciding on a 7-Series FPGA, please read about the other FPGA types offered by Xilinx. These are the UltraSCALE series (faster, lower power) and Zynq-SoC (FPGA + embedded processor).  A good place to start your reading is <this> page.

 

However, based on what you’ve said, I personally feel that the 7-Series would be a good fit.   Xilinx quarterly reports have often said that the 7-Series is a very successful product.  It is still listed as an “Advanced Product” which hopefully means it will be around for a while.  How long?  Well, <this> post says that “popular part/packages have been sold for more than 15 years in some cases, even longer.”  The 7-Series FPGAs came out in 2010.

 

Another decision to make is whether you plan to purchase (at ~$3K/yr) the Vivado software/support or go with the free-of-charge Vivado WebPACK software (and no support except via this Forum).

 

Now to your questions.

 

  1. Is this chip available in the form of an evaluation board so that I can easily implement my code on it just by connecting the signal into the right input pins and also a usb or other inputs for programming?

If you decide to purchase Vivado (and yearly support for Vivado), then you have many boards to choose from.  However, if you plan to use Vivado WebPACK then you should select a board that has an FPGA that is supported by WebPACK (see Table 2-1 in UG973).

 

You can buy boards from Xilinx with FPGAs that are not supported by WebPACK and (I think) they come with a working-version of Vivado that is locked to the board.   However, when you later make your own board with the same FPGA then you will (I think) need to purchase Vivado.  See <this> post for more information.  

 

You can start your board search <here>.  If you have decided to go with the 7-Series then click on “Browse by Device Family” and select either Virtex-7, Kintex-7, or Artix-7.  I do not recommend the Spartan-7 as this is different and older technology.  For example, I note that all the Kintex-7 boards offered by Xilinx use the XC7K325T FPGA which is not supported by WebPACK.   However, you might check the “MIAMI Kintex 7 160T” shown <here> which seems to use the XC7K160T that is supported by WebPACK.

 

2 - Does these evaluation boards provide external clocking option or not?

 

I think you will find that many boards provide this option. However, be aware that this external clock is for the FPGA logic and is not the main clock for the XADC digitizer.  The sampling rate (ie. main clock) for the XADC can be configured in software and has a range of about 100-1000 KSPS.

 

-best of luck,

Mark

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Observer arablu_m
Observer
1,478 Views
Registered: ‎07-05-2018

Re: External Clock FPGA

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Thank you Mark. This was very useful and helpful and I've almost decided about the boards that I should buy. I have one final question before that though; if the XADC is not synchronized to the external clock source then the whole process that I want to develop is broken. I'm not sure whether I understood your answer regarding external clocking or not. Do you mean that there is another on-board clock which times the sampling rate of the XADC via the software? Or the software, VIvado or WebPACK, uses the same external clock to develop a timing for the XADC? If the latter one is true, then the XADC is synchronized to the external clock and that's what I'm looking for.

 

Thanks,

Masoud

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1,462 Views
Registered: ‎01-22-2015

Re: External Clock FPGA

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You are welcome, Masoud.

 

For a 7-Series FPGA, a single clock is usually brought into FPGA and routed to a Clock Management Tile (CMT).  The CMT is then configured by you to produce all the clocks needed in your design.  The frequency range for clock inputs to the CMT is about 10-1000 MHz.  The frequency range for clock outputs from the CMT is about 5-1000 MHz. Clock inputs and outputs of the CMT are all synchronous.

 

You will be able to send one of the CMT output clocks to the XADC clock-input called DCLK.  Xilinx document, PG091 (page 41), says that the XADC clock (ADCCLK) is derived from DCLK.  The Vivado software tells me that DCLK must be at least 52MHz in order to achieve the 1000KSPS maximum sampling rate for the XADC.

 

So, in short, the XADC clock (ADCCLK) is synchronous with the CMT input-clock and output-clock(s).

 

Mark

 

PS. You will find a more detailed description of the XADC in chapter 5 of Xilinx document UG480

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Observer arablu_m
Observer
1,417 Views
Registered: ‎07-05-2018

Re: External Clock FPGA

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Thank you all. Your feedback was very eye-opening and solved my problem on how to choose the right board for my specific application.

Kind Regards,
Masoud
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