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FPGA speeds and recommendations

  1. Dec 3, 2013 #1
    I don't know much about FPGA's but I think I need one for a pet project. I had a few questions for any Verilog pros.

    Do they make them fast enough to process bytes at 48 MHz (DSP basically). I'm sure they do make them somewhere but can you get one cheap?

    Can you load a VHDL program to an FPGA using an ordinary microcontroller or do FPGA's need special hardware setups for flashing them? Most tutorials I've been looking at require programming dongles. That's fine for software development but I'd like to put one a board of my own making eventually.

    Can anyone recommend a brand? I'm looking for one that has really good documentation including board layouts, programming timing diagrams, recommended components, large selection, free development tools, etc.
  2. jcsd
  3. Dec 3, 2013 #2

    48MHz is a pretty slow clock speed for FPGAs, but it depends on the nature of your "processing" (can you elaborate, is it just multiply-accumulates?)

    You can load FPGA from microcontroller, but you will have to write/obtain the necessary code. Dongles are generally used to allow FPGA programming during development/debug (eliminating the software dependency).

    There are only a handful. Go to Wikipedia page for FPGA, they are listed at bottom. They all have good documentation. Development tools may be your issue. You may want to focus on this first. I believe that the major FPGA vendors (Xilinx/Altera) only give this out for free to large customers.
  4. Dec 3, 2013 #3
    The DSP I'm talking about is going to be video compression. Basically I want to make a barebones codec with very little compression so that you can receive a video feed with extremely low latency. The FPGA would package pixel data coming in at 48MHz into packets and send that to a microcontroller with IP capability.

    I'm not sure what kind of FPGA I should go for. Is there free software out there for Verilog? It would be cool if I could write what I want and get reports on what kind of hardware I need to realize it.
  5. Dec 5, 2013 #4


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  6. Dec 5, 2013 #5
    I don't know where you are located but here in the UK you can get an Altera Cyclone IV FPGA for about £15, which has a maximum clock rate of 472.5MHz. However, there are a few disadvantages when you use an FPGA in your circuit:
    • An FPGA doesn't have an internal oscillator. You need to use an oscillator chip or make your own oscillator.
    • The core voltage for the Cyclone IV, for example, is between 1.15V and 1.25V and the maximum output voltage for the IO banks is 3.3V.
    • Altera's FPGAs do not have internal FLASH. You need an external FLASH chip to store the configuration data. On power up the FPGA loads the configuration data. You can download your code on the FLASH chip through the parallel cable. The FLASH can be connected in various ways to the FPGA e.g. parallel, SPI etc.

    I am familiar only with Altera's devices. You can download the free version of Quartus from their webside, which includes a free version of ModelSim for simulation.

    The clock rate of the FPGA is somewhat misleading. This is the maximum rate for the D-type flip-flops but if your delay is longer, you need to decrease your clock rate. Generally, if you need to increase the speed of the encoding, you will put more parallel blocks together. I can give you some advice, if you post what you want to do exactly.

    See Figure 8-6 on page 20 here. Also on pages 4 and 5 you can see the configuration file size.
    Last edited: Dec 5, 2013
  7. Dec 5, 2013 #6
    Thanks very much for your replies. It looks like Altera is the way to go. They have video DSP libraries and tables that show the DSP performance on their different core families. I'm checking out their software.
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