back to article Free for every Reg reader – and everyone else, too: Arm Cortex-M CPUs for Xilinx FPGAs

If you've ever wanted to embed cheap-and-cheerful Arm Cortex CPU cores into your Xilinx FPGA designs, well, now's your chance. The processor designer is making its 32-bit microcontroller-grade Cortex-M1 and M3 cores available for Xilinx's Spartan, Artix, and Zynq chips via its DesignStart program. We're told there are no …

  1. Johnny Canuck

    But will it play...

    ahh... never mind,

  2. Paul

    risc-v fears?

    I agree that risc-v must be making Arm fearful of losing sales, offering these designs isn't something they'd do normally

    1. Tom 7

      Re: risc-v fears?

      They're only giving them away free for the Xilinx stuff - that would be at levels where the accountancy/licensing cost probably exceed the revenue. But if they can help you get started then when you go custom they get a share of that.

      I wonder if you can get 8 Arm cores and highways on a Artix7 gate array for less than a production equivalent though?

      1. Steve Todd

        Re: risc-v fears?

        FPGAs are always slower and more expensive than the equivalent design in an ASIC. It’s just the nature of the beast (it needs to be larger than an ASIC as there’s lots of general purpose stuff in there that may or may not be used, and the distance between functional blocks is larger so signal propagation is slower). This includes putting CPUs in soft format on an FPGA.

        If it is too expensive to create an ASIC, or the design is subject to change, and the task at hand is well suited to parallel execution in hardware, then this is the use case for an FPGA.

        Both Altera/Intel and Xilinx are producing FPGAs with hard ARM CPUs these days (Cyclone V SE models from Altera and ZINQ models from Xilinx). These ARM cores can run much faster than soft cores while being easy to connect to the FPGA logic (AXI or AMBA protocols for example).

        Intel are starting to add FPGA bocks to Xeon processors so that custom hardware acceleration can be added to traditional sequential programs.

        1. This post has been deleted by its author

        2. Mage Silver badge
          Boffin

          Re: FPGAs are always .... than the equivalent design in an ASIC

          ASIC is only cheaper in very high volume. A niche design may not be economic. Speed is less of an issue than power. The ASIC will always be lower power. Often exactly the same speed, as the FPGA is the prototype of the ASIC.

          The FPGA tools produce the files needed to make the ASIC. It's a question of volume, size and power consumption if the ASIC is produced.

          1. Anonymous Coward
            Anonymous Coward

            Re: FPGAs are always .... than the equivalent design in an ASIC

            >>The FPGA tools produce the files needed to make the ASIC.

            Ah, many's the project that came a cropper thinking that transitioning an FPGA to full ASIC was just a question of, "generating some files."

            1. Anonymous Coward
              Anonymous Coward

              Re: transitioning an FPGA to full ASIC

              "many's the project that came a cropper thinking that transitioning an FPGA to full ASIC was just a question of, "generating some files."

              Undoubtedly true.

              Now, is that a reason for going FPGA, going ASIC, or is it a reason for **understanding the available options and choosing the right tool for the job**, like IT people do. IT people always choose the right tool for the job, don't they.

    2. ChrisPVille

      Re: risc-v fears?

      Not only that, but it's a way for ARM to poke Intel/Altera in the eye.

  3. Mage Silver badge

    ARM and Royalty.

    They are not like Qualcomm.

    An M0 chip starts at 50c. There can't be much royalty anyway. Also isn't Qualcomm the only "double dipper"? You buy their chips AND have to pay a fee based on the value of what it's used in? Nice phone you have there.

    1. Anonymous Coward
      Anonymous Coward

      Re: ARM and Royalty.

      >Also isn't Qualcomm the only "double dipper"?

      Are they? One of their defences is that this is the industry norm. Also comparing an M0 with a Snapdragon which is a SoC that also contains multiple processors, GPU, DSP, ISP and other parts seems a bit misleading.

  4. Anonymous South African Coward Bronze badge

    Excuse my ignorance, but what can this be used for in the real world?

    1. martinusher Silver badge

      Re: What are they used for

      >Excuse my ignorance, but what can this be used for in the real world?

      See my post about servo drive coprocessors. FPGAs are actually really useful for small and medium volume industrial equipment, anything that needs an intelligent subsystem that might have custom peripherals. FPGAs themselves replace most discrete logic; these parts are extremely capable; typically their main design limitation is that you run out of input / output pins.

      You can actually run Linux on a FPGA based processor but you don't usually do this because its not an efficient use of logic resources, if you want an actual computer rather than an embeddable processor then you're better off using a processor subsystem SoC like the device used in a Raspberry Pi.

      1. Nial

        Re: What are they used for

        "typically their main design limitation is that you run out of input / output pins"

        It depends what you're using, the biggest Artix device has 500 IO pins.

        ?

    2. Lee D Silver badge

      Isn't the Cortex M3 the chip used in the Arduino devices?

      https://en.wikipedia.org/wiki/ARM_Cortex-M#Cortex-M3

      Basically, this means you can make an Arduino-compatible board from an open-core processor.

      That's a pretty big plus for the hobbyist electronics people.

  5. martinusher Silver badge

    Does the word "Microblaze" ring a bell?

    Xilinx have a soft processor for their FPGA lines, its been around for decades. Its a fairly generic RISC they call "Microblaze". Along with the processor they supply a lot of different peripherals so its possible to build quite a complex system on a FPGA. For example, we use them as communications coprocessors for servo drives -- you can pack a processor, UART(s), network interface (which could be the rather complex Ethercat interface), CAN peripheral, and various bits of RAM (dual port and standard) and still have room for things like encoder interfaces.

    Xilinx isn't the only company offering processors. I think everyone does -- I know Altera and Lattice do -- and they offer both the more comprehensive 32 RISC and a simple 8 bit device. Some of these devices can be quite cheap; Lattice's parts in particular are too cheap to bother turning into ASICs unless you're in the toy business or something like that.

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