FPGA's for A/D

[Scarr]

Hi all,

Never used FPGA's but just watched a few videos and they look really quite good, so, I have a few questions I am sure you guys will be able to answer

• I would like to create a A/D sampler would this a be an easy thing in FPGA?
• What FPGA would be a good starting point for this project (I think I am right in saying a flash type FPGA would be best so I don't need loader etc)?
• What is the simplest FPGA language (ideally free and bearing in mind I am used to MCU's with C / Basic and can do assembly)

What would be great is a Arduino type FPGA, buy a FPGA nano+A/D shield+RAM Shield write some quick code (I know, I know VHDL etc)

Any advice is much appreciated

Steve

 

[ronsimpson]

Most FPGAs are "digital" and a A/D is "analog".

 

[AnalogKid]

An Arduino is not a type of FPGA, and FPGA's cannot do A/D conversion. There are programmable analog chips similar to programmable digital chips like CPLD's and FPGA's, but they are not complex enough to do A/D conversion. What is the task you are trying to achieve?

ak

 

[tomizett]

I assume the OP wants to build some kind of system that will control an A/D converter and do something with the result... As Ron and AK have said, of course the FPGA can't do a conversion on its own, but could be interfaced to an A/D converter chip. You can get microcontrollers with built-in A/D converters but the same is not true (as far as I know) of FPGAs.

Funilly enough I'm just getting started in FPGA world myself - be warned, it's a *steep* learning curve, but very interesting. When I first started considering playing with one, nearly 10 years ago, the cost of development boards was prohibitive - but now there are some that are quite affordable.

Firstly, you'll need a development board. All FPGAs come in large surface mount packages that don't make for easy prototyping; they also need some support circuits like voltage regulators (often a few rails are required) and a configuration EEPROM.
The board that I have cost about £30 (GB pound) and has an Altera CycloneII FPGA - that's an old product now, but plenty capable for a beginner. It was purchaced through eBay, but via a friend so I'm afraid I can't tell you the name of the seller or exactly how it was listed. It also came with the JTAG/USB programming interface - you will need something like this, although many boards have this on-board meaning you simply plug in USB directly.

I believe (please correct me if I'm wrong here people!) that all the FPGA manufacturers provide a free version of their development tools. These are *massive* pieces of software (>5GB download) which you will need to install on your PC. I don't believe there are any "generic" tools for synthesis. Altera even do a version that runs under Linux - that's one of the main reasons I went for their product.
Regarding languages, yes, it's a choice between VHDL and Verilog. I chose VHDL (for some reason I can't recall any more), although I can currently barely say "hello world" in it. For this reason I'm having a go at designing as a schematic to get used to doing logic design.

Regarding development boards, Lattice do some very small and cheap ones which may be of interest. The Altera baord I have is an "unoffical" Chinese product and, although mine works perfectly, you may get better support with a vendor's own official board and programmer.

If you let us know where in the world you are/what suppilers you have access to, perhaps someone can recomend a particular product for you to buy?

**EDIT**
PS. As AK said, do you have a particular task you need to do or is it for the joy of leaning? If the former, then perhaps soneone can suggest the most direct route to achieving it.

 

[Scarr]

Sorry, I do realize you need a A/D chip and probably some RAM, but I just thought it might be as easy as adding these IC's dropping a sampler block onto a graphical interface, setting some sample rates and hey presto a fast A/D sampling system, then do the reverse to replay the sample.

SCarr

 

[tomizett]

I get the impression that that kind of convenience is the kind of thing that comes with interlectual property that you have to pay for - the penalty for using the free tools seems to having to roll your own more often.

I have a feeling that I've read something about integration with Matlab/Simulink, which would give you that rapid-prototyping environment. Dunno what tools you'd need for that though.
I'm afraid that's pretty much exhausted my knowledge on the subject; I'm sure others will be able to point you in the right direction.

 

[Mikebits]

There are a few companies that make FPAA devices, usually based on switched capacitor technology. They are the analog equivalent to the FPGA. If you want more info let me know.
You still need to know some fundamentals in electronics.