Survey: FPGA PCB layout

In article <6PQOj.21063$%41.8783@nlpi064.nbdc.sbc.com>, 
notthisjoergsch@removethispacbell.net says...
> John Larkin wrote:
> > On Sun, 20 Apr 2008 14:13:21 -0700, Joerg
> > <notthisjoergsch@removethispacbell.net> wrote:
> > 
> >> John Larkin wrote:
> >>> On Sat, 19 Apr 2008 14:17:44 -0700, Joerg
> >>> <notthisjoergsch@removethispacbell.net> wrote:
> >>>
> >>>> Nico Coesel wrote:
> >>>>> Dave <dhschetz@gmail.com> wrote:
> >>>>>
> >>>>>> Does anybody out there have a good methodology for determining your
> >>>>>> optimal FPGA pinouts, for making PCB layouts nice, pretty, and clean?
> >>>>>> The brute force method is fairly maddening. I'd be curious to hear if
> >>>>>> anybody has any 'tricks of the trade' here.
> >>>>> I start thinking about how the PCB should be routed the minute I start
> >>>>> to draw a schematic. I always draw components with their actual
> >>>>> pin-outs. This helps to group pins together and it helps to
> >>>>> troubleshoot the circuit when the prototype is on your bench (no need
> >>>>> to lookup the pinouts because they are in your diagram).
> >>>>>
> >>>> For quad opamps like the LM324 as well? That can make a schematic harder 
> >>>> to read and will also cause a nightmare if the layouter wants to swap 
> >>>> amp A with amp C and stuff like that.
> >>>>
> >>>> [...]
> >>> A quad opamp doesn't have 1738 pins!
> >>>
> >> Well, yes, I was just wondering about whether Nico really always draws 
> >> the physical package. Looks like he doesn't for smaller stuff.
> >>
> >> With 1738 pins you can only hope that the FPGA has enough routing 
> >> resources. That used to be a major pain in the early 90's. Don't know 
> >> about nowadays since other guys design the parts with the big FPGAs. And 
> >> I am glad I don't have to deal with BGA, at least not with large ones ...
> > 
> > The biggest ones we use are Sparten 3's with 456 balls on 1 mm
> > centers. We haven't had any routing problems so far, doing pretty
> > complex stuff at 128 MHz clock rates. Our in-house BGA soldering
> > yield, to date, is exactly 100%. BGAs seem to be a lot easier to
> > solder reliably than fine-pitch leaded parts. Easier to inspect, too,
> > since you can't inspect them at all.
> > 
> 
> The latter is a concern in my field (medical). We need to be able to 
> inspect. The other concern is involuntary board flexing. Most of my 
> designs have to sustain under tortures such as freighter pilots 
> ploughing through a storm in the Carribean in airplanes as old as a DC-3 
> or a trucker in Africa who is lead-footing it over a few hundred miles 
> of washboard road.
> 
X-Rays?

-- 
Keith

On Sun, 20 Apr 2008 18:10:04 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

>
>John Larkin wrote:
>> 
>> On Sun, 20 Apr 2008 17:33:16 -0400, "Michael A. Terrell"
>> <mike.terrell@earthlink.net> wrote:
>> 
>> >
>> >John Larkin wrote:
>> >>
>> >> A quad opamp doesn't have 1738 pins!
>> >
>> >
>> >   That will only happen if Bloggs designs it. :(
>> 
>> Bloggs has several times stated that he doesn't design electronics. He
>> hasn't stated what he actually does.
>
>



>  He stated that he does absolutely nothing.  It might be the only time
>he has ever told the truth.

Sounds boring. No wonder he's usually bummed.

John

John Larkin wrote:
> 
> On Sun, 20 Apr 2008 18:10:04 -0400, "Michael A. Terrell"
> <mike.terrell@earthlink.net> wrote:
> 
> >
> >John Larkin wrote:
> >>
> >> On Sun, 20 Apr 2008 17:33:16 -0400, "Michael A. Terrell"
> >> <mike.terrell@earthlink.net> wrote:
> >>
> >> >
> >> >John Larkin wrote:
> >> >>
> >> >> A quad opamp doesn't have 1738 pins!
> >> >
> >> >
> >> >   That will only happen if Bloggs designs it. :(
> >>
> >> Bloggs has several times stated that he doesn't design electronics. He
> >> hasn't stated what he actually does.
> >
> >
> 
> >  He stated that he does absolutely nothing.  It might be the only time
> >he has ever told the truth.
> 
> Sounds boring. No wonder he's usually bummed.


   No reason to live if you have nothing to do. :(


-- 
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Use any search engine other than Google till they stop polluting USENET
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On Apr 21, 3:24 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> John Larkin wrote:
>
> > On Sun, 20 Apr 2008 18:10:04 -0400, "Michael A. Terrell"
> > <mike.terr...@earthlink.net> wrote:
>
> > >John Larkin wrote:
>
> > >> On Sun, 20 Apr 2008 17:33:16 -0400, "Michael A. Terrell"
> > >> <mike.terr...@earthlink.net> wrote:
>
> > >> >John Larkin wrote:
>
> > >> >> A quad opamp doesn't have 1738 pins!
>
> > >> >   That will only happen if Bloggs designs it. :(
>
> > >> Bloggs has several times stated that he doesn't design electronics. He
> > >> hasn't stated what he actually does.
>
> > >  He stated that he does absolutely nothing.  It might be the only time
> > >he has ever told the truth.
>
> > Sounds boring. No wonder he's usually bummed.
>
>    No reason to live if you have nothing to do. :(
>
> --http://improve-usenet.org/index.html
>
> Use any search engine other than Google till they stop polluting USENET
> with porn and junk commercial SPAM
>
> If you have broadband, your ISP may have a NNTP news server included in
> your account:http://www.usenettools.net/ISP.htm

I used to use a newsreader with the servers at RCN.  But I can't get
the reader to find the servers anymore.  Actually, it seems to be an
account validation thing and dealing with RCN support is such a pain
that I am willing to put up with the SPAM until it becomes
unbearable.  When that happens I will do without newsgroups.  A lot of
the important stuff is handled in highly targeted forums anyway.  I
mainly come here to see what others are doing and having problems with
and to ask an occasional question.  I seem to recall that a question I
asked a month or so ago resulted in a lot of crap being thrown
around.  That is almost as bad as the SPAM and no ISP can filter it!

krw wrote:
> In article <6PQOj.21063$%41.8783@nlpi064.nbdc.sbc.com>, 
> notthisjoergsch@removethispacbell.net says...
>> John Larkin wrote:
>>> On Sun, 20 Apr 2008 14:13:21 -0700, Joerg
>>> <notthisjoergsch@removethispacbell.net> wrote:
>>>
>>>> John Larkin wrote:
>>>>> On Sat, 19 Apr 2008 14:17:44 -0700, Joerg
>>>>> <notthisjoergsch@removethispacbell.net> wrote:
>>>>>
>>>>>> Nico Coesel wrote:
>>>>>>> Dave <dhschetz@gmail.com> wrote:
>>>>>>>
>>>>>>>> Does anybody out there have a good methodology for determining your
>>>>>>>> optimal FPGA pinouts, for making PCB layouts nice, pretty, and clean?
>>>>>>>> The brute force method is fairly maddening. I'd be curious to hear if
>>>>>>>> anybody has any 'tricks of the trade' here.
>>>>>>> I start thinking about how the PCB should be routed the minute I start
>>>>>>> to draw a schematic. I always draw components with their actual
>>>>>>> pin-outs. This helps to group pins together and it helps to
>>>>>>> troubleshoot the circuit when the prototype is on your bench (no need
>>>>>>> to lookup the pinouts because they are in your diagram).
>>>>>>>
>>>>>> For quad opamps like the LM324 as well? That can make a schematic harder 
>>>>>> to read and will also cause a nightmare if the layouter wants to swap 
>>>>>> amp A with amp C and stuff like that.
>>>>>>
>>>>>> [...]
>>>>> A quad opamp doesn't have 1738 pins!
>>>>>
>>>> Well, yes, I was just wondering about whether Nico really always draws 
>>>> the physical package. Looks like he doesn't for smaller stuff.
>>>>
>>>> With 1738 pins you can only hope that the FPGA has enough routing 
>>>> resources. That used to be a major pain in the early 90's. Don't know 
>>>> about nowadays since other guys design the parts with the big FPGAs. And 
>>>> I am glad I don't have to deal with BGA, at least not with large ones ...
>>> The biggest ones we use are Sparten 3's with 456 balls on 1 mm
>>> centers. We haven't had any routing problems so far, doing pretty
>>> complex stuff at 128 MHz clock rates. Our in-house BGA soldering
>>> yield, to date, is exactly 100%. BGAs seem to be a lot easier to
>>> solder reliably than fine-pitch leaded parts. Easier to inspect, too,
>>> since you can't inspect them at all.
>>>
>> The latter is a concern in my field (medical). We need to be able to 
>> inspect. The other concern is involuntary board flexing. Most of my 
>> designs have to sustain under tortures such as freighter pilots 
>> ploughing through a storm in the Carribean in airplanes as old as a DC-3 
>> or a trucker in Africa who is lead-footing it over a few hundred miles 
>> of washboard road.
>>
> X-Rays?
> 

They tend not to penetrate through metal so well and are frowned upon at 
the work place.

-- 
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

On Apr 21, 3:24 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> John Larkin wrote:
>
>    No reason to live if you have nothing to do. :(
>
> --http://improve-usenet.org/index.html
>
> Use any search engine other than Google till they stop polluting USENET
> with porn and junk commercial SPAM
>
> If you have broadband, your ISP may have a NNTP news server included in
> your account:http://www.usenettools.net/ISP.htm


What is the point of including a link to the "improve usenet" page?  I
don't see any useful information there.  The page complains about a
few things and offers no advice on what to do about any of it...
counter to its stated purpose of being "an attempt to make Usenet
participation a better experience for those who are clued as to what
the Usenet medium is and how to use it".  Instead of offering anything
constructive, they even insult people that they should be trying to
reach and convince... "most of the people who post to Usenet via the
clunky Google Groups web interface are lusers or lamers".

Do you think that this page has had any sort of positive influence on
usenet?  Does your posting the link help in any way?

rickman wrote:
>> your account:http://www.usenettools.net/ISP.htm


> 
> I used to use a newsreader with the servers at RCN.  But I can't get
> the reader to find the servers anymore.  Actually, it seems to be an
> account validation thing and dealing with RCN support is such a pain
> that I am willing to put up with the SPAM until it becomes
> unbearable.  When that happens I will do without newsgroups.  A lot of
> the important stuff is handled in highly targeted forums anyway.  I
> mainly come here to see what others are doing and having problems with
> and to ask an occasional question.  I seem to recall that a question I
> asked a month or so ago resulted in a lot of crap being thrown
> around.  That is almost as bad as the SPAM and no ISP can filter it!

If you have an account with RCN, the news servers name is

news.rcn.com

It is connected to port 119 (as are all news servers).

The authentication information is:

your email account name (eg. blahdeblah@rcn.com),
and your password is the same as the password for your email program.

It really is quite simple.  RCN does have a few news outages from time
to time, but generally they are very reliable.

-Chuck

rickman wrote:
> 
> On Apr 21, 3:24 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
> wrote:
> > John Larkin wrote:
> >
> >    No reason to live if you have nothing to do. :(
> >
> > --http://improve-usenet.org/index.html
> >
> > Use any search engine other than Google till they stop polluting USENET
> > with porn and junk commercial SPAM
> >
> > If you have broadband, your ISP may have a NNTP news server included in
> > your account:http://www.usenettools.net/ISP.htm
> 
> What is the point of including a link to the "improve usenet" page?  I
> don't see any useful information there.  The page complains about a
> few things and offers no advice on what to do about any of it...
> counter to its stated purpose of being "an attempt to make Usenet
> participation a better experience for those who are clued as to what
> the Usenet medium is and how to use it".  Instead of offering anything
> constructive, they even insult people that they should be trying to
> reach and convince... "most of the people who post to Usenet via the
> clunky Google Groups web interface are lusers or lamers".
> 
> Do you think that this page has had any sort of positive influence on
> usenet?  Does your posting the link help in any way?


   Yes.  It has a link to the current version of News Proxy, and a lot
of people have installed it because of that link.  More and more are
completely filtering out Google Groups in protest of the spam they dump
on Usenet.  I will probably stop tagging Google Groups messages and drop
them, starting on May first.


-- 
http://improve-usenet.org/index.html


Use any search engine other than Google till they stop polluting USENET
with porn and junk commercial SPAM

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm

Hi Joerg,

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message 
news:PLsOj.7522$GE1.332@nlpi061.nbdc.sbc.com...
> Private companies generally offer zilch in retirement benefits. Those days 
> are long gone.

Actually I think a very significant fraction of companies (at least those 
hiring EEs) offer some sort of contribution to 401k plans, sometimes profit 
sharing, sometimes stock options, etc... but I concur that the old days of 
"company pensions" is pretty much gone.

> A 70 year old programmer can be better than a 40 year old.

Absolutely, but if you're an employer it's definitely a legitimate 
consideration that starting a bunch of 70-year-olds on a, say, decade-long 
"modernization" project is rather riskier than if you toss a few 50- or 
30-year-olds into the mix as well. :-)

> Anyhow, why should retirement checks be based on the last year of service? 
> IMHO that's wrong.

I agree that one year seems too short, but trying to figure out how many years 
should be taken into consideration (which is effectively what happens in 
private companies if the company is contributing to your 401k) is not going to 
be easy either.

---Joel

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message 
news:coen041brmqf342022figkpv9ogjol2h0i@4ax.com...
> Easier to inspect, too,
> since you can't inspect them at all.

I'm sure you know this, but plenty of places will X-ray BGAs to "inspect" 
them.