From: Alessandro Basili on
Hi everyone,
I'm just about to start an implementation of an open spacewire IP core
(still trying to understand under which license, GPL, LGPL, CeCILL...)
and I was wondering whether is a good idea to have a wishbone interface
implemented.
I am pretty new to SoC bus and even though google is "one of my best
friends" I still didn't get the feeling how popular it is and how spread
it is at the moment or will be in the future.
If anyone has any opinion I would be glad to listen to it.
Thanks a lot,

Al

--
Alessandro Basili
CERN, PH/UGC
Hardware Designer
From: Rob Gaddi on
On Fri, 19 Mar 2010 16:29:54 +0100
Alessandro Basili <alessandro.basili(a)cern.ch> wrote:

> Hi everyone,
> I'm just about to start an implementation of an open spacewire IP
> core (still trying to understand under which license, GPL, LGPL,
> CeCILL...) and I was wondering whether is a good idea to have a
> wishbone interface implemented.
> I am pretty new to SoC bus and even though google is "one of my best
> friends" I still didn't get the feeling how popular it is and how
> spread it is at the moment or will be in the future.
> If anyone has any opinion I would be glad to listen to it.
> Thanks a lot,
>
> Al
>

I use it a lot on my projects, though I rarely bring in any 3rd party
IP. The thing about a WISHBONE bus is that it's really just a
consistent way of naming the minimal set of signals you'd need to have
a SoC bus. Data, address, chip select, read/write, return data and a
handshake.

As compared to other SoC buses I've looked at, WISHBONE takes far less
coding effort to deliver somewhat less performance. It's a simple
enough thing that you can make practically any kind of slave, or any
kind of master, talk to it. The lack of pipelining can kill your
throughput if you're really having to push a lot of data, but for most
applications it's plenty sufficient.

--
Rob Gaddi, Highland Technology
Email address is currently out of order
From: d_s_klein on
On Mar 19, 8:29 am, Alessandro Basili <alessandro.bas...(a)cern.ch>
wrote:
> Hi everyone,
> I'm just about to start an implementation of an open spacewire IP core
> (still trying to understand under which license, GPL, LGPL, CeCILL...)
> and I was wondering whether is a good idea to have a wishbone interface
> implemented.
> I am pretty new to SoC bus and even though google is "one of my best
> friends" I still didn't get the feeling how popular it is and how spread
> it is at the moment or will be in the future.
> If anyone has any opinion I would be glad to listen to it.
> Thanks a lot,
>
> Al
>
> --
> Alessandro Basili
> CERN, PH/UGC
> Hardware Designer

I have worked with 3 "externally defined" on-chip buses:
1) Avalon (Altera)
2) OPB (sp?) (Xilinx)
3) Wishbone (GPL/Lattice)

Semi-random opinions:

Expanding on Rob's comment, using a bus that "someone else" defines
means that there's one less definition that *you* have to do; this is
a good thing.

The NIOS and EDK buses are mostly useful in their manufacturer's tool-
chain, and their devices. The translation from Avalon to Wishbone is
trivial though.

I had to sign an 'NDA' with IBM to get the documentation for the EDK
bus. This didn't make a lot of sense to me.

The Wishbone is popular enough that IP vendors will code to it without
a lot of resistance. This isn't always true with proprietary buses.

There you go; a bunch of reasons to use it, and none (so far) to NOT
use it.

RK


From: HT-Lab on

"Alessandro Basili" <alessandro.basili(a)cern.ch> wrote in message
news:ho059b$hpl$1(a)speranza.aioe.org...
> Hi everyone,
> I'm just about to start an implementation of an open spacewire IP core (still
> trying to understand under which license, GPL, LGPL, CeCILL...) and I was
> wondering whether is a good idea to have a wishbone interface implemented.

Depending on what you want to do with the core but I would suggest you also have
a look at the Amba bus since (thanks to Gaisler research?) this bus seems to be
gaining popularity amonst the space/mil-aero users.

Hans
www.ht-lab.com


> I am pretty new to SoC bus and even though google is "one of my best friends"
> I still didn't get the feeling how popular it is and how spread it is at the
> moment or will be in the future.
> If anyone has any opinion I would be glad to listen to it.
> Thanks a lot,
>
> Al
>
> --
> Alessandro Basili
> CERN, PH/UGC
> Hardware Designer


From: Alessandro Basili on
On 3/19/2010 5:56 PM, HT-Lab wrote:
>
> Depending on what you want to do with the core but I would suggest you also have
> a look at the Amba bus since (thanks to Gaisler research?) this bus seems to be
> gaining popularity amonst the space/mil-aero users.
>

Indeed I was trying to understand the main differences just because I
know that there are IP cores available which are interfaced with AMBA,
but the main idea behind is to have a copyleft license on the core,
mainly to share it in the academic community, especially for those
science projects which are space related.

Al
--
Alessandro Basili
CERN, PH/UGC
Hardware Designer