On Wed, 23 Sep 2015 22:02:21 -0400, rickman wrote:
> On 9/23/2015 7:22 PM, lasselangwadtchristensen@gmail.com wrote:
>> Den onsdag den 23. september 2015 kl. 21.16.36 UTC+2 skrev rickman:
>>> On 9/23/2015 2:50 PM, Tim Wescott wrote:
>>>> On Wed, 23 Sep 2015 14:18:15 -0400, rickman wrote:
>>>>
>>>>> On 9/23/2015 1:42 PM, Tim Wescott wrote:
>>>>>> On Tue, 22 Sep 2015 13:56:57 -0400, rickman wrote:
>>>>>>
>>>>>>> On 9/22/2015 1:46 PM, Tim Wescott wrote:
>>>>>>>> On Tue, 22 Sep 2015 17:07:42 +0000, Rob Gaddi wrote:
>>>>>>>>
>>>>>>>>> On Tue, 22 Sep 2015 10:33:20 -0400, rickman wrote:
>>>>>>>>>
>>>>>>>>>> To date, the two large FPGA companies are sticking to the path
>>>>>>>>>> that got them where they are, catering to the large comms
>>>>>>>>>> companies needs which is bigger, faster FPGAs. There is a lot
>>>>>>>>>> more margin at the high end than at the low end. Motor control
>>>>>>>>>> would definitely be the low end. Someone has already complained
>>>>>>>>>> about FPGA prices in this thread.
>>>>>>>>>>
>>>>>>>>>> There is nothing stopping FPGAs from being built like MCUs with
>>>>>>>>>> all manner of accessories built in. But the big guys aren't
>>>>>>>>>> going to do it.
>>>>>>>>>> The new market for FPGAs is in very high volume handheld
>>>>>>>>>> devices.
>>>>>>>>>> The
>>>>>>>>>> new push is to low end FPGAs in very small packages and price
>>>>>>>>>> will be a major issue. So far there aren't many pushing in
>>>>>>>>>> that direction. The processes are still digital. But once they
>>>>>>>>>> broach this market more they will be more inclined to break out
>>>>>>>>>> of their mold and explore more innovative areas like motor
>>>>>>>>>> control with analog subsystems.
>>>>>>>>>
>>>>>>>>> Actually, both X and A have SoC offerings now that integrate ARM
>>>>>>>>> Cortex A9s with a mess of peripherals alongside the fabric.
>>>>>>>>>
>>>>>>>>> I'm actually really surprised at the balance they struck; they
>>>>>>>>> both decided to put a LOT of hard IP in. Gb Ethneret MAC, DRAM
>>>>>>>>> controller,
>>>>>>>>> all that stuff makes sense to me to harden. But they're also
>>>>>>>>> putting SPI, I2C, counter/timers, all the sort of stuff that
>>>>>>>>> seems like it would be just as easily implemented on the fabric.
>>>>>>>>> Beats me what the logic was.
>>>>>>>>
>>>>>>>> You can implement stuff in much less space (and probably power)
>>>>>>>> if it's hard-coded rather than implemented in the FPGA fabric --
>>>>>>>> that's why there's a processor core in there and not just
>>>>>>>> available IP. The logic extends to peripherals: if it's
>>>>>>>> something that's used a lot, then it's worthwhile putting in. I
>>>>>>>> suspect that the area difference is 10:1, which would mean
>>>>>>>> (roughly) that if you put in 10 different peripherals and each
>>>>>>>> customer used one and let the other 9 lie idle, that you'd break
>>>>>>>> even on area and come out ahead on power consumption.
>>>>>>>
>>>>>>> Saving area is only useful if you *use* the IP.
>>>>>>
>>>>>> No, saving area is only useful if it makes the chip less expensive
>>>>>> or (assuming I care) consume less power. If 10 peripherals,
>>>>>> together, are smaller and less expensive than the generic fabric I
>>>>>> need to implement the one I actually use, then I don't give a crap
>>>>>> about the unused 9 -- I'll just chortle happily every time I review
>>>>>> the BOM.
>>>>>
>>>>> What does the BOM have to do with it? None of this will add any
>>>>> parts or is at all likely to require a larger part. If this was the
>>>>> guiding principle to adding hard IP, there would be a lot more hard
>>>>> IP on a lot more FPGAs.
>>>>
>>>> Man, if I said "what does the BOM have to do with it" to a customer
>>>> for whom I was designing a board, I would only have myself to blame
>>>> if they hung up on me and expunged me from their files.
>>>>
>>>> BOM "has to do with it" because BOM cost matters. It just does.
>>>>
>>>>>> If I'm trying to minimize power consumption and the one peripheral
>>>>>> I use takes 1/3 the power (I'm just inventing numbers in my head
>>>>>> here, BTW) that I'd need to implement it in the fabric, then I may
>>>>>> be willing to pay _more_ for the chip, even.
>>>>>>
>>>>>> So, I disagree.
>>>>>
>>>>> Trouble is all your numbers are made up and it assumes that all
>>>>> designs using that FPGA will use *any* of the added hard IP.
>>>>
>>>> Well, yes, my numbers are made up, for illustrative purposes. I'm
>>>> assuming that -- being an engineer -- you know how to get the gist of
>>>> what I'm saying without getting hung up on the specific numbers.
>>>>
>>>> My point is made even if not all designs using an FPGA use any of the
>>>> added IP. If Xilinx can make one chip with added hard IP for cheaper
>>>> than it can make two chips, one with the added IP and one without,
>>>> and if it passes that savings on to its customers, then the people
>>>> who use the chips without ever turning on the hard IP benefit from
>>>> having a chip to use in the first place.
>>>>
>>>> Since you don't want me to use made-up numbers, I'll just use
>>>> inequalities. If X > Y > Z represent three dollar amounts, would you
>>>> Xilinx sold chip x (with hard IP that you don't have to use) and chip
>>>> y (without), at costs X and Y, or would you rather Xilinx sold only
>>>> chip x at cost Z, or would you rather pay a premium for chip y so
>>>> that you can use it without offending your sensibilities?
>>>
>>> Actually this is not the comparison. If chip Y is cheaper than chip
>>> X and also cheaper than chip Z, then offer the SPI, I2C, etc as soft
>>> IP and be done with it. Quit making stuff up!
>>>
>>>
>> that's not what he wrote,
>>
>> x cost X, y cost Y, but if y wasn't build x could be sold for Z
>>
>> only one chip need to be designed, everyone saves money and those who
>> doesn't need the extra stuff can ignore it
>
> That's my point. His example doesn't include the case of just building
> Y and no X or Z.
X, Y and Z are dollar amounts. Do you understand this discussion?
> X has the extra hard logic and Y can be built for less
> than any of the above.
And (assuming you mean x and y), all the people who did want that hard IP
start buying their chips from someone else, and the executive who decided
not to make x gets the opportunity to be in charge of marketing for some
other company.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com