Parts obsolescence is biting again, and at least one of my EEs is
insisting that we spin replacement boards with soft-core processors in
FPGAs.

There are several things I don't like about that.

First, how robust are these systems.  What if power is lost during
updating the configuration device?

Second, I don't like the holy wars among our EEs.  Most of them use
Altera and wouldn't touch Xilinx to save their lives.  But one guy
uses only Xilinx and won't give the Altera rep the time of day.  This
hasn't bothered me up until now, when we put together a peripheral
that is accessed to a microcontroller or DSP, because we define an
interface and they meet it.  I don't need to care who the FPGA source
is.

But if we're talking soft core, I'm not going to allow our embedded
software department get saddled with supporting both NIOS and Micro
Blaze.

So third, I'd be grateful for any experiences with either soft core,
or even better both, with a comparison between the two.

And does anybody have any experience with the synthesizable ARM soft
core for FPGA?  Unless there's a serious handicap, I'd prefer ARM if
we do soft core, we've already good tools and programmer experience.

Any and all comments, real or delusional, welcome.

Rene wrote:

What is the reason that Your opinion about Xilinx is so negative?

ISE vX.Y. It is complete and utter rubbish. Absolute garbage. Crap. Piece
of sh*t. (You get the point?!?)

Others claim that Xilinx is OK if you steer clear of ISE (the GUI) and use
command-line tools. I have no comment on that, except I have one project
that synthesises a mux with up to 16 inputs. On Altera, I have no problem
with 16 inputs. On Xilinx, the synthesis craps out after about 12. I'm not
saying my design in this instance is particularly good - I inherited part
of the design - but at least it works under Altera.

Mark McDougall wrote:
Rene wrote:

What is the reason that Your opinion about Xilinx is so negative?

ISE vX.Y. It is complete and utter rubbish. Absolute garbage. Crap. Piece
of sh*t. (You get the point?!?)

Let me see... I get a vague inkling that You are not impressed with the
qualitiy of the ISE pack, is that correct? ;-)

Others claim that Xilinx is OK if you steer clear of ISE (the GUI) and use
command-line tools. I have no comment on that, except I have one project
that synthesises a mux with up to 16 inputs. On Altera, I have no problem
with 16 inputs. On Xilinx, the synthesis craps out after about 12. I'm not
saying my design in this instance is particularly good - I inherited part
of the design - but at least it works under Altera.

Hmmm, both Your and Antti's story don't sound very positive when it
comes to ISE. It is really a PITA when software is very unreliable. I
recently bought a Nexys2 board, I hope I am not going to regret it.
Fortunately for now it is only for hobby purposes, am looking forward to
start experimenting with it. Let's hope that in some time the
imperfections in the ISE get ironed out.

Thanks for both of Your opinions.

Take care,
Rene

And does anybody have any experience with the synthesizable ARM soft
core for FPGA? Unless there's a serious handicap, I'd prefer ARM if
we do soft core, we've already good tools and programmer experience.

And does anybody have any experience with the synthesizable ARM soft
core for FPGA?  Unless there's a serious handicap, I'd prefer ARM if
we do soft core, we've already good tools and programmer experience.

I expect that ARM instruction set has gotten uglier over time (like
everyone else's), but it used to be fairly simple. Simple enough that
you could emulate it in software on some other processor, with good
performance. If you can emulate an ARM instruction in 10 native
instructions, and your native processor is 10x as fast as an FPGA, go
with emulation.

FPGAs are fun and all, but the don't buy much speed in a serial process
like instruction execution for a simple processor.