FPGA or Microcontroller?

Discussion in 'Embedded Systems and Microcontrollers' started by Peter Pan, Jan 6, 2008.

  1. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
    122
    0
    Hello All,

    I have a general question about making right choice between FPGA and microcontroller for my digital system.
    My system has to generate precise RF pulse trains of frequency about 10 MHz and variable pulsewidths and delays between pulses ranging from 0 to hundreds milliseconds in steps of 1 microsecond. Edges of pulses has to be very precise within about 50 nS. Phase of each pulse (in relation to clock signal) can be 0, 90, 180, 270 degrees.
    The system has to be controlled by a user through PC host run under Windows (or Linux). There will be a need for special software which I will write later.
    What is your opinion, whether FPGA or microcontroller is most suitable for this project?
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Hi,

    This is a pretty tough call, is it for a one-off project or production? If it is for a one-off, then I'd recommend buying a Spartan 3 development kit. You can get them fairly cheap and it is more than adequate to get the job done. If it is for production, then you'll want to do it with a microcontroller. Microcontrollers do not require as much care in decoupling and three supply voltages, not to mention all the extra IOs you won't be using.

    I know the PSoC has a PWM block that can do the resolution and speed that you're talking about, but I am not so sure about the precision of the delays and the phase of your input clock.

    Basically, if you want to ensure it will work well and you can get the best performance and flexibility, you should use an FPGA. Again, this decision should be made only if it is a single-run project. You shouldn't bother trying to create your own FPGA development board, you should buy an eval. kit.

    Steve
     
  3. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
    122
    0
    Thank you, Steve. It's not for production and I am really inclined to use FPGA just because it's more modern and can be reprogrammed thoroughly. However I wonder why you suggest that if it has to be for production then this task is for microcontrollers? I assume that one-off project could be microcontroller-based as well, or it couldn't?
     
  4. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    For production, you really want to minimize costs.. Microcontrollers are much much cheaper to buy and house on a PCB.

    FPGAs require boot PROM, a ton of caps, three or more supplies, and sometimes a more advanced PCB technology. This all equals $$$

    Steve
     
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