Useful EVMs for FPGA Developemnt Boards

[zygot]

It's not easy adding Analog to your Digital for non-audio applications on a typical FPGA development board. I thought that some of you might find my experiences with the following useful. All of the following can be found from a distributor like Mouser or Digi-Key.

You have to be careful because, especially for high speed ADC/DAC EVMs a lot of boards have HSMC and FMC type connectors that aren't compatible with the standard interfaces. Sometime you can cobble up a work-around but usually not. Before spending any money on an EVM you need to do this**:

• Read the data sheet for the featured device very very carefully to make sure that it can do what you want it to do. This is not nearly as simple as you would think, especially  for ADC devices  where specmanship, little white ( sometimes closer to black ) lies, and covering up 'features' that might render the device useless for your requirements has always been the rules of the road.
• Pore over the schematic for the EMV and trace every pin through the connector to ensure compatibility with your FPGA board. Pay particular attention to power supply pins.
• Download the supporting software, when available, and understand what you get or don't.
• Understand that good ADC interfaces, on the analog side, tend to be very application specific. The ADC demo boards tend to be general purpose; but not always. Not listed below is the ADS4449 EVM  that I managed to get working with the KC705 board a number of years ago. This 4 channel high speed ADC EVM is set up for narrowband processing of signals centered around 185 MHz. It served it's purpose but I can't recommend it.

         
HSMC compatible boards.

ADC/DAC

Linear Technology DC2459A LTC1668 16-bit 50 Msps DAC 

This is one of those rare EVMs designed to connect to an FPGA development board. It can connect directly to a board with an HSMC connector, a DE0 Nano, a Mimas or Mojo board.  Mine is always attached to a DE0 Nano and ready to go. I use an external TTL USB UART for control. The DE0 Nano is a cheap and very handy board to have around. ( If only it had a nice Artix FPGA... not that I have anything against the Cyclone V )
 
Linear Technology DC2390A for LTC2500-32. 2 LTC2500-32 32-bit ADCs and 2 LTC1668 16-bit 50 Msps DACs

Connects to any FPGA  board with an HSMC connector. The EVM is intended to be used with the Cyclone V SoCkit and has slick software support if used with this ARM based board. I prefer rolling my own interface and using another FPGA platform. Interesting approach o the software side.
 
Terasic makes a couple of not too expensive ADC/DAC HSMC compatible add-on boards. I've already posted a description of a demo project that I completed ( well as far as I need to for now ) recently showing one way to use the Ethernet PHY to make use of such boards. In recent years I've really lost my enthusiasm for low end Intel FPGAs and Quartus tools so that post isn't as silly as you might assume that it is.

USB 3.0

Both FTDI and Cypress offer reasonably priced development kit options for using their USB 3.0 interface devices for both HSMC and FMC connector equipped boards. In fact for the FMC versions these are among the only inexpensive mezzanine boards that you will find. I much prefer the flexibility of the Cypress FX3 but be aware that you need to do some embedded ARM development and there's a steep learning curve. If you want to learn about USB this is the way to go.

FMC compatible boards.

The FMC ecosystem is, with few exceptions, a very expensive place to play in. However on rare occasions you can get lucky. Understand that none of the boards below were intended to connect directly to an FPGA development board.

Analog Devices EVAL-AD7761FMCZ AD771 8-channel 16-bit Simultaneous Sampling ADC.

I've used this board with the Nexys Video with minimum effort. This is one of those devices where you can be very disappointed if you don't completely understand everything in the data sheet.

Analog Devices EVAL-AD7616SDZ AD7616 16-Channel DAS Dual Simultaneous Sampling ADC.

This board requires a SDP-I-FMC interposer. I didn't complete a project using it but haven't run into any obstacles hardware-wise. This is another device that requires very careful scrutiny before deciding that you want to spend your time or money on it.

** This advice also applies to FPGA boards that you are thinking of purchasing.

• If you want to use a particular feature, say DDR, find out if the vendor offers a usable demo showing how you might use  it for your project. Find out if you need an evaluation license to build the demo for yourself in order to use that feature. There's only one way to do this...

1.  Before making a purchase install Vivado or ISE and see if  you can actually build the demo projects for a board.
2.  Support, support, support. So what kind of support is provided for the board that you are interested in? Digilent is all over the place here. A very few boards have demo projects with HDL sources. One such board is the Nexys 7-A100T (Nexys 4 DDR) that has an OOB with VHDL sources for most of it's features. It does have a few IP .xco files that are supposed to work with Vivado 2018.2. I was unable to use the sources to generate a bitstream using Vivado 2018.2 SP1. ( I don't have the board so I didn't spend a lot of time trying only because I wanted to look at the DDR IP to reply to a posted question regarding DDR performance.
3. Companies can pretend to offer more support than they really do by offering board design Xilinx IP flow demos. I personally, want to see HDL source as a measure of commitment to a  product. Even though Digilent has shown that it's possible; it's hard to mess up an HDL demo.
4. If there's very little in the way of providing build-able demo projects for board features or it take years to provide  a reasonably accurate User's Manual these are big red flags. It doesn't mean that the board is useless, just that you had  better have the experience and skill, and most importantly for me the time to write your own interfaces

    
    
Tips for beginners.

• Not everything that board or even IC vendor makes is wonderful. If they spent money developing a product then they sure will try to find a customer to pay for those    development costs. Sometimes, the only way to identify the dirty little secrets is to observe what's missing in a data sheet or sales blurb. If a normal feature is usually    highlighted for most similar products and noticeably absent for the one that you are eyeing then this is a big red flag. What's missing is sometimes more informative than what's stated.

[zygot]

I forgot to mention the MAX11254 EVM. If you need a high resolution multi-channel delta-sigma ADC for low frequency applications this board is very usable. It was designed to be used in a stand alone mode via a USB interface or with the Zedboard; so it should work with either the Nexys Video or Genesys2 boards as well. There are a lot of options for using your own input signals. It has 50 or so jumpers to locate, which makes it flexible, but may make you cross-eyed for a few days trying to locate all of them. There just aren't that many pins in the FMC interface to trace through which is nice.

[JKing]

HELLO

Recently, I had a problem just like this. I have read many  material. But I still can not confirm.

I currently have the KC705? OR KCU105 FPGA board. 

I want to buy a DAC board AD9142A-M5375-EBZ or AD9122-M5375-EBZ with an adapter AD-DAC-FMC-ADP.

My question is, how do I find out if the DAC evaluation card with adapter board is compatible with the fpga board? Will the FPGA board support the DAC running with the maximum data rate ?
THANKS!

[zygot]

1 hour ago, King said:

want to buy a DAC board AD9142A-M5375-EBZ or AD9122-M5375-EBZ with an adapter AD-DAC-FMC-ADP.

Well, I can only tell you to do what I do, as mentioned at the top of the thread. If the board vendor had demo code for a board that is designed to run on a platform that you have then you should be ok, though I'd probably still run through the schematics. Even then you have to build the demo to determine if there are any surprises, like proprietary IP sources, that you can't modify or need a license for, because it's unlikely that what you want to do is what the demo does. I've had mixed experiences from Analog Devices which has, on the face of it, excellent FPGA support. I've used the AD9739A-FMC-EZB with the KC705 with success. ( guess I forgot to mention that earlier )

Once you start thinking about adapters it's clear that you are on you own, without demo code. In this case make sure that you understand how to implement your own interfaces. Be careful of JESD converters as they are tricky and I am unaware of any free IP. Converters with parallel DDR interfaces are the most likely to work with an adapter. There are a lot of flavors of LVDS but your chances of success with an adapter is low, from my experience. There are other threads on this topic that I've written about on Digilent's Forums. In my experience using an adapter has worked out for low performance converters using singled-ended signalling.

The best approach to evaluating new hardware is 'try before you buy'. If there's no demo code for your platform you need to figure out what the pin location assignments for your platform will be and design a test project to see if there are any gotchas you didn't think of. Why would anyone spend money first and then figure out if their purchase if usable?

Never make assumptions. The devil is in the details and sometimes hiding on purpose.

[JKing]

Hi zygot

There are something I have forgot to say. The AD9122 board and AD9142A board are LVDS interface, and the FPGA board are FMC interface. So the DAC can not  be inserted directly.
The ADI said the AD-DAC-FMC-ADP adapter board allows any of AnalogDevices' DPG2-compatiable High-Speed DAC Evaluation Boards (just like AD9122 and AD9142A) to be used on a Xilinx evaluation board with a FMCconnector. The adapter board uses the Low Pin Count (LPC)version of the FMC connector, SO it can be used on either LPC or HPC hosts (such as the ML605, SP605, KC705, etc.) But I havenot seen any demo code about it. So I a little worried about it could be matched.

You said that the chances of success with an adapter is low from your experience. Could you please tell the reasons so that I can understand.

There are little material about the adapter. So I haven’t figured out how it worked. In my understanding , it just works as a Interface converter, but I can’t still confirm it.

What you said last is very ture. So I will look for more information to confirm. If I find the answer,  I will share with you.

Thanks.

Sincerely !

 

 

[zygot]

1 hour ago, King said:

The ADI said the AD-DAC-FMC-ADP adapter board allows any of AnalogDevices' DPG2-compatiable High-Speed DAC Evaluation Boards (just like AD9122 and AD9142A) to be used on a Xilinx evaluation board with a FMCconnector.

In my experience that statement is over optimistic. I'm always on the lookout for opportunities to use an off the shelf converter with one of my many FPGA boards equipped with an FMC connector. I've used the adapter that you refer to but successes are the exception. Even for simple single-ended interfaces the process of figuring out what the pin location assignments will be end up in failure due to some signal not making it to a pin on my FPGA board, Often, the issue is a 12V or other power supply issue. Every time I start the analysis it starts with creating a net connection diagram in text.

For the AD9122 you have a parallel differential data interface so you might get lucky. I have a folder with every converter and converter EVM that I think is interesting and that device is there so I must have at least given it some thought... but no, I don't remember actually doing a signal connection diagram for it. That might be because the device is a bit old but don't really remember. Understand that an adapter will add delays to your timing budget and likely pair mismatches. While not necessarily a show stopper it might make a project quite complicated 

For LVDS with multiple lanes of high data rate multiplication relative to a clock references things get complicate fast. I've gone though the exercise of doing the pin location analysis for quite a few FMC equipped EVMs only to find that the reference clock or clock assignments were not correct. This has nothing to do with the FMC connector but the pin assignments by the FPGA board vendor. There are restrictions for clocking and data pin IO banks. I've discussed this in more detail elsewhere on Digilent Forums. 

One thing to be careful of with converters is that for actual implementations the analog conditioning is very application dependent. EVMs are generally designed to evaluate a device, not be suitable for any particular application.

At the end of the day you are the one stuck with any choice that you make so do your homework even if someone says that a combination of FPGA boards and mezzanine cards works for them.

Unfortunately, vendors of FPGA boards would like to think that the FMC standard carries some universal compatibility guarantee with it but they never offer a money back purchase guarantee or even bother to test a selection of mezzanine cards that their customers might want to use. So the burden is on the customer. I've bothered to post a few threads about my experiences in the interests of vendors and their customers alike. IO bank assignments matter. There is no universal interface. That's what I've found.

Now the FMC can be a plug and play interface if the mezzanine card and carrier card vendors use that EEPROM but the FMC specification really doesn't cover all of the issues that are pertinent for FPGA carrier details. At least I haven't run into very many FMC mezzanine cards that use the EEPROM to set Vadj or identify feature or interface requirements.

Things are looking up though as Digilent has decided to support the SYZYGY specification for some of its nwere boards. This is a plug and play interface with FPGA carriers in mind. It will take some time for device vendors to latch on and likely a few specification iterations before this becomes a real benefit to most FPGA developers but my hopes are high. That's saying a lot as my past experiences jave always kept driving me toward pessimism.

Oh, and about the Kintex UltraScale, Be careful with the newer devices as the IO banks might only support Vadj up to 1.8V and are incompatible with older FMC mezanine cards that use 2.5V or 3.3V IOSTANDARDs.

[JKing]

Hi zygot

Thanks a lot.

Form your experience , maybe I should consider changing the DA board. 

 

Thank you for your  warm reply.

Sincerely 

[zygot]

14 hours ago, King said:

Form your experience , maybe I should consider changing the DA board. 

It really all depends on what you what to do. What is that you intend for you DAC project?

[JKing]

Hi zygot.

I have bought the AD-9142A-M5375 board half years ago. Something has delayed. Recently, I used it work with KC705, It works fine.So come and share this experience with you.

[zygot]

@JKing,

I'm glad to hear that it all worked out for you. Thanks for posting your information.