Low cost and/or small size CPU in an FPGA

[hamilton]

What is the lowest cost and/or the smallest CPU in an FPGA.

Can a CPU with reasonable code space fit into a 44 pin FPGA ?

Are there any 44 pin FPGAs ?

hamilton

[rickman]

Lol, that is a humorous transistion. You might want to start with the
last question. There might be some parts from Lattice in the iCE40
series that are in packages with that pin count. I know they have some
small ones, but mostly they are *very* fine pitch BGA/LGA type parts.

Why the concern with the pin count? Usually people need a minimum, not
a max. They may have size concerns, but that is not closely tied to pin
count. I prefer parts with large pin pitch (0.5 mm minimum) to ease
board design issues. So I often have to live with 100 pin parts and
larger. If you need a tiny part, you can get some very small parts, but
they will be larger pin counts that 44 pins in most brands.

As to the CPU, take your pick. The J1 seems to be a pretty good design
with 16 bit instructions that can map to multiple Forth primitives.
Bernd Paysan has a b16 with 5 bit instructions which is fully fleshed
out and usable. I think he has two flavors, a larger and a smaller
implementation.

There are others too, but I don't have them on the tip of my tongue.

--

Rick

[hamilton]

On 4/24/2013 10:10 AM, rickman wrote:
> On 4/24/2013 9:37 AM, hamilton wrote:
>> What is the lowest cost and/or the smallest CPU in an FPGA.
>>
>> Can a CPU with reasonable code space fit into a 44 pin FPGA ?
>>
>> Are there any 44 pin FPGAs ?
>>
>> hamilton
>
> Lol, that is a humorous transistion.

Ok, my goal.

I need a uP and some logic, but I would like to do it with one part.

208 pins just won't fit into my package.

Thanks

hamilton

[David Brown]

On 25/04/13 06:19, hamilton wrote:
> On 4/24/2013 10:10 AM, rickman wrote:
>> On 4/24/2013 9:37 AM, hamilton wrote:
>>> What is the lowest cost and/or the smallest CPU in an FPGA.
>>>
>>> Can a CPU with reasonable code space fit into a 44 pin FPGA ?
>>>
>>> Are there any 44 pin FPGAs ?
>>>
>>> hamilton
>>
>> Lol, that is a humorous transistion.
>
> Ok, my goal.
>
> I need a uP and some logic, but I would like to do it with one part.

Consider looking at this from a different direction. You say you need
"some" logic, which implies that you don't need a lot. Are you sure an
FPGA is necessary? There are lots of microcontrollers around with
advanced peripherals that can negate the need for some logic. And since
many of these micros are very fast, you can perhaps do the "logic" tasks
in software.

Then there are the "hybrid" devices such as the PSOC or XMOS that could
perhaps do the job.

You might also be better off with a dedicated microcontroller and a
small flash PLD. Before we know what sort of microcontroller power you
need, and what sort of logic you need, you can't get good help.

Be specific about what you are trying to do, and people can give better
advice - at the moment it is like going into a library and asking for a
book with 8 chapters and a green cover.

>
> 208 pins just won't fit into my package.
>

Do you mean you don't have the physical space on your board? Do you
have other restrictions on the package types you can use, the density,
number of layers, etc.? After all, a 44-pin PLCC package takes about as
much space as a modern 800-ball BGA - so number of pins is meaningless
on its own.

And have you considered everything else around the planned FPGA, such as
power supplies for multiple rails, oscillators, flash chips for the
configuration, etc.? These can quickly take up more space than the FPGA
itself.

> Thanks
>
> hamilton
>

[Tom Gardner]

6502: 3150 transistors, 6800: 4100 transistors, 8080: 4500 transistors
So yes, you certainly ought to be able to get them inside an FPGA.

But that leads onto the more important point: what toolchain are
you going to use to program the processor? You may decide that is
the tail that should wag the dog.

[thomas....@gmail.com]

Of course it depends on your exact requirements, but nowadays your are often better of with a small Cortex-Mx (e.g. NXP LPC or Freescale Kinetis) + small FPGA (or CPLD) (e.g. Altera MAX V or Lattice iCE40/MachXO2 have small packages and integrated config-memory).

The uCs are highly integrated, having flash, ADC, clock oscillator, brown-out-detection, etc. integrated. With the FPGA only approach, you often need separate parts for this.

If you want to go with the FPGA only approach (e.g. if you need no ADC and only have small code memory requirements), you can check out our ERIC5 soft core CPU which is extremely small:
http://www.entner-electronics.com/tl/index.php/eric5.html

BTW, if you are using Altera parts, you might also be interested in our EEBlaster ;-)
http://www.entner-electronics.com/tl/index.php/eeblaster.html (EUR 49,-)

Regards,

Thomas

[AMD...@gmail.com]

You can get a mico8 core to fit in a lattice Mach XO2-640 in a 100 pin lqfp, not a huge amount of code space, although how much depends on how you split up the block ram resources.

[jg]

>
> Ok, my goal.
> I need a uP and some logic, but I would like to do it with one part.
> 208 pins just won't fit into my package.

That's both very broad, and vague.
How much uP and how much Logic ?

You can get 'some logic' as small as QFN32, (Xilinx, Lattice) but if you really want both in one package, look at Cypress PSoC series.

I think the new PSoC4 comes in 44 pins, and fits "a uP and some logic"

[hamilton]

I am looking at using the SAM4L in a 48 TQFP @ 48Mhz.

I can use software to create a 100nSec pulse.

Thanks

hamilton

[Pendlebury Chumbleton]

"hamilton" <hami...@nothere.com> wrote in message
news:klr4oh$6h3$1...@dont-email.me...

Really? You can do most things in software, but creating 100ns pulse from a
48MHz clock without any hardware assist is sure gonna be tricky!



Pendlebury