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    Small size FPGAs: Actel or Lattice

    Hello, for a major project coming up, I know I'll need to use small size (like under 1cm square) FPGAs. Exactly what they need to do, I'm not exactly sure. I've done some digging and found that Actel's and Lattice make very small FPGAs, so I'm trying to pick between the two right now. I had a couple questions comparing the two:

    1. When comparing the architecture of the two, it seems that the Igloo nano logic elements are much simpler and less capable than the Lattice iCE40 ones. Igloo's VersaTiles can be a 3 input LUT or a latch/flip flop, while the iCE40 logic elements are a 4 input LUT and a flip flop. So for an equivalent amount of LEs, I presume the iCE40 stuff will be much more powerful, right?

    2. The development software is a huge deal to me. I have experience with Quartus II and found it decent, while Xilinx's software was awful in my experience. So I want to get a feel for which brand has an easier learning curve. At first I'll probably be sticking with free licenses (it seems both companies offer functional free versions of their tools), so please keep that in mind. I prefer doing my design in verilog, but VHDL would be okay too. Will I have to pay for functional simulation? Also having some kind of in-circuit debugger similar to signaltap (from Altera) would be nice.

    3. Also I'll definitely be starting out with a dev board, not a custom PCB (no way I could solder 0.4mm BGA by hand). Anybody have experience with their dev boards? In this regards I think Actel has a big advantage
    Actel's igloo nano board: http://www.actel.com/products/hardwa...o_starter.aspx
    Lattice's ICE40 board: http://www.latticesemi.com/products/...valuationk.cfm

    The iCE40 board looks like a joke. Very bare, but it has a few capacitive touch pads which I have no use for. Contrast that with the Igloo board which has nice features (really liking that you can adjust the voltages on the I/O banks).

    At this point I'm torn, but I think the software is going to be the main factor.

    Thanks in advance,
    -Mike
    Last edited by mtwieg; 30th June 2012 at 17:05.

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    Re: Small size FPGAs: Actel or Lattice

    Actel uses Synplify Pro for synthesis.
    I think Lattice is also using it with the Diamond software.

    For P&R Actel uses the "Designer" software - which I really don't like.
    Device wise - I'd go with the IGLOO FPGA.


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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by shaiko View Post
    Actel uses Synplify Pro for synthesis.
    I think Lattice is also using it with the Diamond software.
    So they both use the same tool to synthesize code into logic? How is that possible when their architectures are so different?
    For P&R Actel uses the "Designer" software - which I really don't like.
    Device wise - I'd go with the IGLOO FPGA.
    What do you mean by P&R, and what about it is bad? And what do you like about the Igloo devices?



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    Re: Small size FPGAs: Actel or Lattice

    So they both use the same tool to synthesize code into logic? How is that possible when their architectures are so different?
    Synplify is the synthesis tool only...just so it happens, Synopsys has special versions that support both Actel and Lattice

    What do you mean by P&R
    Place & Route.
    I find the Actel Desiner - user unfriendly. Also, it often crashes (with the 2 PC's I tried it on)

    What do you like about the Igloo devices?
    1.Power consumption is the lowest you'll find in the FPGA market.
    2.True fabric nonvolatility - although Lattice has some devices with on-chip PROM, it's still an SRAM device (while the ACTEL's fabric itself is nonvolatile FLASH)
    3.Single voltage operation - this makes them easier to integrate on PCB with less required power supplies.

    But with a package size of 10mm x 10mm both Altera and Xilinx aren't out of the equation. They both have interesting devices to offer ( Look at the Spartan 6 and Cyclone IV ).

    My suggestion:

    1. If power consumption and PCB space are the main issues - go with the IGLOO nano
    2. If you need the best tools and best performance go with the Spartan 6 or Cyclone IV
    3. If you need some hardened ready to use peripherials go with the MachXO 2 from Lattice.


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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by shaiko View Post
    Place & Route.
    I find the Actel Desiner - user unfriendly. Also, it often crashes (with the 2 PC's I tried it on)
    Okay, noted...

    1.Power consumption is the lowest you'll find in the FPGA market.
    2.True fabric nonvolatility - although Lattice has some devices with on-chip PROM, it's still an SRAM device (while the ACTEL's fabric itself is nonvolatile FLASH)
    3.Single voltage operation - this makes them easier to integrate on PCB with less required power supplies.

    But with a package size of 10mm x 10mm both Altera and Xilinx aren't out of the equation. They both have interesting devices to offer ( Look at the Spartan 6 and Cyclone IV ).
    Yes now that I look carefully I do see that there are a couple Cyclone IV devices in a 8x8mm MBGA. But I can't find it for sale at any distributor anywhere... not good.
    My suggestion:

    1. If power consumption and PCB space are the main issues - go with the IGLOO nano
    2. If you need the best tools and best performance go with the Spartan 6 or Cyclone IV
    3. If you need some hardened ready to use peripherials go with the MachXO 2 from Lattice.
    Power consumption isn't even that big a deal for me. I don't know what my performance requirements are (it may not even be under my control). But I'm starting to lean back towards Altera. I just wish they made smaller parts (which are actually available to purchase).



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    Re: Small size FPGAs: Actel or Lattice

    But with a package size of 10mm x 10mm both Altera and Xilinx aren't out of the equation.
    Not exactly, there's a smaller number of suitable Altera devices below 10x10 mm, but mtwieg didn't mention a required LE count or other essential features, so nothing to suggest so far.



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    Re: Small size FPGAs: Actel or Lattice

    It's hard for me to pin down a required number of LEs, since the functionality of the system hasn't been specified yet. It will have to communicate via fiber with a system that hasn't been designed yet, with a communication scheme that hasn't been designed yet. And neither of those things will probably be under my control. Even so I'm supposed to determine the optimal parts to use for my end of the design. What fun!

    Overall I'd guess the design won't need more than 5000 LEs, and maybe 1KB of onboard SRAM. I'd like to have some breathing room to play around with, though.



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    Re: Small size FPGAs: Actel or Lattice

    Hi mtwieg,

    Did you look at the iCE40 series FPGA product table from Lattice (previously from SiliconBlue Technology). This product is specially for mobile and handheld devices with least power consumption and small size. Please check following link
    http://www.latticesemi.com/products/...ries/index.cfm
    You get SynplifyPro software for synthesis and for PnR you will use iceCube2 software from Lattice.

    Thanks,
    Fpgadsgnr.



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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by fpgadsgnr View Post
    Hi mtwieg,

    Did you look at the iCE40 series FPGA product table from Lattice (previously from SiliconBlue Technology). This product is specially for mobile and handheld devices with least power consumption and small size. Please check following link
    http://www.latticesemi.com/products/...ries/index.cfm
    You get SynplifyPro software for synthesis and for PnR you will use iceCube2 software from Lattice.

    Thanks,
    Fpgadsgnr.
    Yes, I had specifically looked at the iCE40 stuff as an option. The devices themselves appear to have the best performance for that size range. Do you know if simulation and in circuit debugging is free from lattice?

    Quote Originally Posted by shaiko View Post
    2.True fabric nonvolatility - although Lattice has some devices with on-chip PROM, it's still an SRAM device (while the ACTEL's fabric itself is nonvolatile FLASH)
    Hi shaiko, could you eleborate on this point a bit more? Does this mean that lattice devices can only be configured once??

    edit: yes, upon further investigation the internal PROM can only be written once! But you can use the devices with an external flash configuration memory. Even so this is a big hit to Lattice for me, since I'll need that external flash....
    Last edited by mtwieg; 2nd July 2012 at 13:41.



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    Re: Small size FPGAs: Actel or Lattice

    Hi shaiko, could you eleborate on this point a bit more? Does this mean that lattice devices can only be configured once??
    No,
    Just to note - Actel does make some FPGAs that use "Anti-Fuse" technology. these can be configured only once.
    However, I wasn't talking about them. The "Igloo" and "ProAsic" series are both FLASH technology. They can be reconfigured (with an endurance of ~500 cycles).

    Take a look at the Xilinx SPARTAN 3AN for example.
    That's the only "non-volatile" FPGA that Xilinx makes. I write "non-volatile" in commas because it's actually volatile.
    The FPGA fabric is still SRAM - but with a configuration FLASH PROM in the same package. With power-down the SRAM fabric is erased and must be reloaded with each power-up.

    Actel is different -
    With Actel, the FPGA fabric itself is FLASH.


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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by shaiko View Post
    No,
    Just to note - Actel does make some FPGAs that use "Anti-Fuse" technology. these can be configured only once.
    However, I wasn't talking about them. The "Igloo" and "ProAsic" series are both FLASH technology. They can be reconfigured (with an endurance of ~500 cycles).
    Right, I was referring to Lattice iCE40 devices only being able to be configured once. I'm surprised that the endurance of the flash on the Igloo devices is only 500 cycles though... for a beginner like me that's probably not enough. Can Igloo devices be configured via JTAG directly, without wearing out the FLASH memory? I'm guessing not, if the flash is truly the FPGA "fabric."
    Take a look at the Xilinx SPARTAN 3AN for example.
    That's the only "non-volatile" FPGA that Xilinx makes. I write "non-volatile" in commas because it's actually volatile.
    The FPGA fabric is still SRAM - but with a configuration FLASH PROM in the same package. With power-down the SRAM fabric is erased and must be reloaded with each power-up.

    Actel is different -
    With Actel, the FPGA fabric itself is FLASH.
    I see, so the Igloo parts don't have any "configuration" process on boot up, hence why they are active so fast after POR.
    Last edited by mtwieg; 2nd July 2012 at 15:38.



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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by mtwieg View Post
    Yes, I had specifically looked at the iCE40 stuff as an option. The devices themselves appear to have the best performance for that size range. Do you know if simulation and in circuit debugging is free from lattice?
    I am not sure about it, you can please go to Lattice site and check.

    Thanks,
    Fpgadsgnr



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    Re: Small size FPGAs: Actel or Lattice

    Quote Originally Posted by mtwieg View Post
    Yes, I had specifically looked at the iCE40 stuff as an option. The devices themselves appear to have the best performance for that size range. Do you know if simulation and in circuit debugging is free from lattice?


    Hi shaiko, could you eleborate on this point a bit more? Does this mean that lattice devices can only be configured once??

    edit: yes, upon further investigation the internal PROM can only be written once! But you can use the devices with an external flash configuration memory. Even so this is a big hit to Lattice for me, since I'll need that external flash....
    I believe in general SRAM based FPGAs are faster than Flash based ones.
    I've used Lattice/Silicon Blue iCE65-series and I got a reasonably fast SRAM FPGA with a built in Non-volatile OTP memory that sets up the basic and time-critical features, and then I reconfigure it from MCU or just from external flash memory for additional features. Don't know if I'll continue use iCE40 (even though it fits more logic because of the 40 nm process) or switch to Microsemi/Actel IGLOO-series for next generation. A lot depends on high User IO with package at 7x7 size at reasonable pricing level.
    Also, using other vendor FPGA SW dev tools and dev boards helped clear out the bigger issues, before I moved to Lattice iCE65-synthesis and dev board.



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    Re: Small size FPGAs: Actel or Lattice

    I have experience using lattice CPLDs. The support is great.
    Actel support is good, but not as good as lattice.
    Both have low cost eval boards.
    Have a look at this video, you wouldn't think of another fpga vendor
    http://www.youtube.com/watch?v=gM2hnra55Hs



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    Re: Small size FPGAs: Actel or Lattice

    All the lattice FPGAs use Diamond as their IDE, which is very nice. Their new iCE40, however, is manufactured by Silicon Blue, which Lattice recently acquired. They use iCEcube2, which, in my opinion, is not nearly as nice as Diamond. Concerning the devboard (which I have), the iCE40 does have a MCU on it that allows USB programming though, which is a plus. They also provide some source code. I have found that their support for this new chip is not quite as good as some of their other FPGAs. . . Good Luck.



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