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Clarissa

problem of board expansion nexys 4ddr

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Hello everybody, I'm a trainee in digital electronics, i should achieve a migration of VHDL codes from the Digilent Nexys 2 which is obsolete to another board, after some researches, I would like to work with the Nexys4DDR board. However, there is a problem of the number of connectors in the Nexys4DDR, in my project, I need at least 40 pins for my signals, it was possible with the Nexys2 thanks to the Hirose FX2 connector which disappears in the new Nexy boards. Should I choose another FPGA board or add an expansion to the Nexys4? In the last case, will there be synchronization problems?

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Hello @Clarissa,

I don't know what your project requirements are, but if you're just looking for the 40 pins, you might want to look into the Arty or the Cmod A7. To be fair, these don't have have the same "amount" of FPGA as the Nexys 4 DDR and neither have video capabilities (I don't know if you were needing that in your project), but they do have at least the 40 pins (which I *think* are all available as general purpose pins) and the Arty also has the DDR memory. 

In terms of an expansion module of some sort for the Nexys 4 DDR to get more I/O pins, there will have to be some delay as you are inevitably going to have to work through another chip with a (de)mux rather than having the signals directly come in on their own dedicated lines to the FPGA, but depending on your design this can potentially be accounted for.

Let me know if you have any more questions or details on your project.

Thanks,
JColvin

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@Clarissa,

If you want to move towards the higher end, the Nexys Video board has an FMC connector on it.  That connector has about 76 single ended connectors available to it, or almost 40 differential connectors.  Other boards have the FMC connector as well--to include the ZedBoard and the Genesys2 development board.  What you want/need really depends upon what you wish to do.

Your call,

Dan

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@JColvin,

Thank you for your answer, in the last version of the project, we have used 26 Pmod pins, 40 Hirose FX2 pins, 3 slide buttons, 4 LEDs and 2 pushbuttons in the Nexys 2 board. We suggest also adding new functions to the project, such as saving data in a sliding table, so more connectors are needed.

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Hi @Clarissa,

We moved to the FMC connector from the Hirose FX2 connector. You would want to look at the boards that  @D@n  suggested above. The Zedboard and Nexys Video being a LPC FMC and the Genesys 2 being a HPC FMC.

cheers,

Jon

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Hi @Clarissa,

I'm mostly echoing what @jpeyron said, but from your project requirements, it looks like the Nexys Video that @D@n mentioned will likely be your best option if you don't want to use some sort of expansion addon. It'll also have some spare pins available for what you are needing since it has 34 differential pairs on the LPC FMC (which from my understanding you can use as single ended pairs) in addition to the four Pmod ports. If you're fine with the expansion options introducing delays, then your options expand to a much wider range since (from what I can tell) you will then be mostly looking to see if the embedded components you are needing exist on the board and if the FPGA has enough "room" for what you need to do.

The Zedboard and Genesys 2 will also work, but have either an entirely different architecture  (an SoC on the Zedboard) or are a much larger and fancy FPGA with a HPC FMC in the case of the Genesys 2.

Let us know if you have any more questions.

Thanks,
JColvin

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@Clarissa,

It is a female socket. Here are the part numbers for the male connector for both the LPC and HPC FMC's. The Nexys Video has a LPC FMC.

HPC: ASP-134488-01

LPC: ASP-134604-01

 Here is a thread that talks about the LPC FMC for the zedboard that might help here as well. Here is a link to some FMC breadout boards. 

cheers,

Jon

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