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Messages from 34125

Article: 34125
Subject: Re: Building a clock out of a PLD
From: Eric Inazaki <penfold@deadbeat.edu>
Date: Tue, 14 Aug 2001 20:44:29 -0500
Links: << >>  << T >>  << A >>
In article <3B79C344.682A@designtools.co.nz>, Jim Granville
<jim.granville@designtools.co.nz> wrote:

> Eric Inazaki wrote:
> > 
> > I have a PLD circuit which requires a clock signal.  I'm thinking it'd
> > be really nice if I could use some of the otherwise unused gates (along
> > with a cap and a couple of  resistors) to generate the clock.  
> > Is this a bad idea, doomed to failure or is this sort of thing done all the
> > time? 
> 
> Somewhere in-between :-)

I'm looking to do something in the few to few-tens of kHz.  Would you
consider that to be at the low end of the scale?

The circuit I have in mind has an inverter whose output is the clk
signal.  This output also feeds a resistor (R1).  The other end of
R1 is connected to a cap (C) and another resistor (R2).  The other
end of R2 goes to the input of a buffer.  The buffer's output, the
inverter's input and the other leg of C are all tied together.  (I
know, pictures would be a big help.)  BTW, is this what you mean by
3 terminal design?

> 
>  Low Frequency RC oscillators, of 2/3 terminal design, are impractical
> in
> CPLD due to lack of pin hysteresis.

Ouch, that could be a problem.  I should go look through my data sheets.
I don't suppose there are any PLDs that have Schmitt trigger inputs 
(either configurable, or hard wired)?

>  For low Freq sources, we use HEF4541, available in SO14.
>  For medium Freq, a TinyLogic single gate makes a good osc source.
> You can quite safely build a 3 terminal OSC, (for higher precision),
> using an external TinyLogic gate and a PLD 'gate'.
> 
> These solutions also keep the Icc down.
> 

For my purposes, if I can't do the PLD thing I'll probably just break
out a 555.  I only need 2kHz or so and accuracy and stability are pretty
much non-issues (or so I hope).

>  At higher freqs, > appx 5MHz, it is possible to construct 2/3 terminal
> osc, with care. You need to do your own margin testing.
> 
>  Better may be to removce the R's and C's entirely:
> 
>  We have designed completely buried oscillators in the ATMEL 
> ATF150X family of cpld, using a chain of foldbacks.
> 

Any chance you could point me towards an app note, text reference 
or sample circuits?

> 
> > With respect to timing circuits in general, can PLDs be used in
> > place of discreet logic gates?  
> 
> If you mean RC timing, like 4528, 4093, 40106, HC14, then no.
> If you mean counter chains, like 4060/4040 then yes.
> 
> 

I'm thinking either a delayed monostable or a straight delay.
The delay and pulse width would be on the order of few to tens
of microseconds.

> ======= 80x51 Tools & PLD IP Specialists  =========
> = http://www.DesignTools.co.nz

Thanks for all the input, you've given me quite a bit to chew on.
I've actually just started doing things w/ PLDs.  PLDs rock, especially
these isp types.

eric

Article: 34126
Subject: Re: WinMe installation
From: "jimmy" <jimmy_siu_@hongkong.com>
Date: Wed, 15 Aug 2001 10:19:11 +0800
Links: << >>  << T >>  << A >>
Dear All,
    After I have successful installed the Xilinx ( the computer told me), I
checked the size of the xilinx folder, it just has about 90MB!! I have
clicked all the things but still small size. Is that having any problem
here??
Thanks a lot




Article: 34127
Subject: Xilinx pin lists in text format
From: allan_herriman.hates.spam@agilent.com (Allan Herriman)
Date: Wed, 15 Aug 2001 04:51:15 GMT
Links: << >>  << T >>  << A >>
Hi,
   Does anyone know where Xilinx hide their pin lists, in text format
(not pdf) on their web site?

I've given up trying to battle the various search engines.

Ta,
Allan.

Article: 34128
Subject: Re: Reconfigurable Computational Accelerator
From: "Dave Feustel" <dfeustel1@home.com>
Date: Wed, 15 Aug 2001 05:34:49 GMT
Links: << >>  << T >>  << A >>
I've been thinking about the i/o interface obstacle that exists between
cpu and pci-bus mediated fpga accelerators for a couple of days now.
I have come to the conclusion that the way to have *really* fast
fpga accelerators is to put a hardwired cpu on the fpga chip along
with the accelerator logic and make the entire application run
directly from the fpga. You now can get fpgas with ARM, Powerpc
and or other custom cpus preprogrammed into them and still have
lots of room for your accelerator logic. IP cores for almost every
commonly used peripheral are available to be incorporated onto
the fpga chip - leave off the interfaces you don't need.
Put the whole thing on a PCI card and plug it into your pc to
make development easier(download through the pci bus).

"Mike Butts" <mbutts@realizer.com> wrote in message news:3B758FB0.B98CA76A@realizer.com...
> Dave Feustel wrote:
> > The real short version is
> > that the PCI bus interface is so slow relative to the
> > speeds of the cpu and accelerator that it usually
> > isn't worth adding an accelerator if the interface
> > is via the PCI bus.
>
> This is often, but not necessarily true.  Accelerator architecture
> totally depends on your application.  This is exactly what Philip
> meant by "how long should a piece of string be".  Not ridicule,
> just maybe a little drier wit than we're used to...
>
> If your application depends on lots of back-and-forth
> between the host and the card in its core kernel, PCI is usually
> a barrier.  Many early research projects in this field found this
> out the hard way.  It's not the bandwidth that matters in such
> cases, it's the latency, the round-trip time for a single operation.
>
> PCI, especially as implemented in modern PCs and workstations,
> can be very bad at that.  Mark Shand gave an excellent and
> most useful paper about this at FCCM '97, that anyone using PCI
> must study:
> Laurent Moll and Mark Shand. Systems performance measurement on
> PCI Pamette. In FPGAs for Custom Computing Machines
>      (FCCM'97). IEEE, April 1997.
> http://www.research.compaq.com/SRC/staff/shand/bib.html
>
> If, on the other hand, your app is a self-contained kernel that
> grinds away mostly on its own, PCI can be fine.  Often signal
> processing apps are like this, with the signal I/O direct to
> the card.
>
> I believe a very big win for reconfigurable computing is for
> apps that demand lots of parallel memory bandwidth, since the
> processor-memory bottleneck is so fundamental to conventional
> computing.  I'm working with a project at Oregon Graduate Institute
> lately to develop a neural network accelerator.  In our case, it's all
> about memory bandwidth.  I/O to/from the host is orders of
> magnitude less.  We're planning a PCI card with as many SDRAM DIMMs
> as we can hook up to some FPGAs for them to grind away on matrix-
> vector multiplies in parallel at 100 MHz.  PCI will just control
> and program the card, and feed inputs and collect results at a
> lazy and latency-insensitive pace.
>
> So tell us more about your application, and maybe we can give you
> better advice.
>
>    --Mike



Article: 34129
Subject: Re: Q: Revision and Database Control for FPGA Designs
From: Rick Collins <spamgoeshere4@yahoo.com>
Date: Wed, 15 Aug 2001 02:34:58 -0400
Links: << >>  << T >>  << A >>
hamish@cloud.net.au wrote:
> 
> Rick Collins <spamgoeshere4@yahoo.com> wrote:
> > Clearcase also makes it hard to do some things such as using labels to
> > track builds.
> 
> Really? Just an extra line in the config spec for your view.
> I agree with Allan.. ClearCase is overkill for most FPGA work (it
> excels for the software engineers), but it's nice overkill to have.
> With project teams of 2-7 FPGA engineers, we use labels and branches
> with good effect. We don't usually need to do much merging though.
> The GUI integration is IMHO really good, but you do have to use
> the command line for non-day-to-day stuff.

Accessing the label is not the problem. It is a chore creating a new
label. It takes some 10 or 12 steps to add a new label and that is only
if you have a current view that exactly matches what you want to label.
In our build process we have to check out about 8 files BEFORE we create
the label. If you forget to check out a file before you make the label,
you have to remember to move the label to the new version. We have seen
many, many mistakes made trying to make a new label which defeats the
purpose of using these labels. 

Don't think that branches and labels are unique to Clearcase. We were
using branches and labels 10 years ago with PVCS and they were not new
then. 

 
> The original poster said he had design components which depended on
> shared sub-components, and that different components might use different
> versions of the same sub-components. I'm not sure how any version control
> system would cope with that; you can only expect to see one version of
> any particular entity at one time. I might even go so far as to say
> that it sounds like a bad idea to need this feature.

I think this statement shows the influence that Clearcase has had on
your thinking about how version control should work. I see the
requirement of different modules needing to access different submodule
versions as being one of label control. The way Clearcase handles it,
you can only access one version at a time, but with labels in PVCS, you
can refer to one version for this component and a different version for
a different component. Of course, you can't have both versions available
at the same instant in time. But if your tool can compile the components
separately and then combine the results, you should be able to support
this unusual means of version control. You just need to perform "get" on
a particular version as you need it, then discard the file before (or
as) you "get" the next version. 


I just happened to find an unused copy of PVCS today. I expect I will be
installing it and giving it a try to see how it stacks up to Clearcase.

-- 

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

Article: 34130
Subject: Replication of FFs in Xilinx XC4000
From: Rick Collins <spamgoeshere4@yahoo.com>
Date: Wed, 15 Aug 2001 03:14:58 -0400
Links: << >>  << T >>  << A >>
We are working on a design in an XC4000 about 64K gates and are having a
problem with register replication. The P$R tool is replicating a FF that
is the critical element of a cross clock domain synchronizer. I call
this a "bad thing". 

We looked at the Xilinx web site and found Answer #3813. This says that
PAR can split a net and duplicate the FF driving it. Of course this will
break a synchronizer, they even mention this. The solution is to use an
environment variable to control this feature. This seems like a very odd
way to control the PAR tool! Is there no option that can be set for
this??? Has anyone else been bitten by this "issue"? Any other
solutions? 

I don't really understand why PAR wants to split this net. The
synchronizer consists of two FFs on the same clock with an AND gate
detecting the two FFs being of different values to generate a single
clock wide pulse. The first FF output feeds only three inputs, yet this
is the net that was split. Anyone understand why this is happening? 


-- 

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

Article: 34131
Subject: Re: Q: Revision and Database Control for FPGA Designs
From: Thomas Stanka <Thomas.Stanka@de.bosch.com>
Date: Wed, 15 Aug 2001 09:19:56 +0200
Links: << >>  << T >>  << A >>
hamish@cloud.net.au wrote:
> 
> Thomas Stanka <Thomas.Stanka@de.bosch.com> wrote:
> > And its no problem to use multiple versions in different directories
> 
> Then are they really the same file? Or are they separate copies of
> a file which was once the same file?

Maybe I miss your question, of course, they are separate copies.
/dir1/file
/dir2/file
where file in dir1 is another version than in dir2. You have no need, to
handle one of the files spezial in any case. While editing an older
file, you get automatically a branch. 
 
> > The only problem I see is to have multiple versions of the same file in
> > the same directory.
> 
> Yes. As Allan points out, you can do that in ClearCase by using
> the full pathname to the version. And that works with labels too,
> which is quite neat. I'd still rather not have to use it though.

In that case the files differ in their names, right ? 
I don't dare thinking about handling different filenames for the same
files with our tools.

bye Thomas

-- 
Thomas Stanka	    
Bosch SatCom GmbH           UC_RA/EMD4 s/UC-RA/BC
Gerberstr. 49         	   Tel. +49 7191 930-1690
Zi. 10/528                Fax. +49 7191 930-21690      
                       Thomas.Stanka@de.bosch.com

Article: 34132
Subject: Re: Q: Revision and Database Control for FPGA Designs
From: allan_herriman.hates.spam@agilent.com (Allan Herriman)
Date: Wed, 15 Aug 2001 07:57:38 GMT
Links: << >>  << T >>  << A >>
On Wed, 15 Aug 2001 02:34:58 -0400, Rick Collins
<spamgoeshere4@yahoo.com> wrote:

>hamish@cloud.net.au wrote:
>> 
>> Rick Collins <spamgoeshere4@yahoo.com> wrote:
>> > Clearcase also makes it hard to do some things such as using labels to
>> > track builds.
>> 
>> Really? Just an extra line in the config spec for your view.
>> I agree with Allan.. ClearCase is overkill for most FPGA work (it
>> excels for the software engineers), but it's nice overkill to have.
>> With project teams of 2-7 FPGA engineers, we use labels and branches
>> with good effect. We don't usually need to do much merging though.
>> The GUI integration is IMHO really good, but you do have to use
>> the command line for non-day-to-day stuff.
>
>Accessing the label is not the problem. It is a chore creating a new
>label. It takes some 10 or 12 steps to add a new label and that is only
>if you have a current view that exactly matches what you want to label.
>In our build process we have to check out about 8 files BEFORE we create
>the label. If you forget to check out a file before you make the label,
>you have to remember to move the label to the new version. We have seen
>many, many mistakes made trying to make a new label which defeats the
>purpose of using these labels. 
>
>Don't think that branches and labels are unique to Clearcase. We were
>using branches and labels 10 years ago with PVCS and they were not new
>then. 
>
> 
>> The original poster said he had design components which depended on
>> shared sub-components, and that different components might use different
>> versions of the same sub-components. I'm not sure how any version control
>> system would cope with that; you can only expect to see one version of
>> any particular entity at one time. I might even go so far as to say
>> that it sounds like a bad idea to need this feature.
>
>I think this statement shows the influence that Clearcase has had on
>your thinking about how version control should work. I see the
>requirement of different modules needing to access different submodule
>versions as being one of label control. The way Clearcase handles it,
>you can only access one version at a time

Rick, Clearcase does what you describe here:

> but with labels in PVCS, you
>can refer to one version for this component and a different version for
>a different component. Of course, you can't have both versions available
>at the same instant in time. But if your tool can compile the components
>separately and then combine the results, you should be able to support
>this unusual means of version control. You just need to perform "get" on
>a particular version as you need it, then discard the file before (or
>as) you "get" the next version. 

The main difference is that you need to change your config spec
between "gets", i.e. get file, change config spec, get (different
version of) file.

The setcs command allows you to change your config spec from a script,
which allows you to automate the process.

Earlier you said that you'd only had training in the GUI for
Clearcase.  The GUI only supports a subset of the available features.

Bye,
Allan.

Article: 34133
Subject: Re: Xilinx pin lists in text format
From: Philip Freidin <philip@fliptronics.com>
Date: Wed, 15 Aug 2001 01:05:43 -0700
Links: << >>  << T >>  << A >>
Here it is:

      http://www.xilinx.com/products/virtex/vpackages.htm

      http://www.xilinx.com/products/virtex/vepackages.htm

      http://www.xilinx.com/products/virtex/v2packages.htm

Philip


On Wed, 15 Aug 2001 04:51:15 GMT, allan_herriman.hates.spam@agilent.com (Allan
Herriman) wrote:
>Hi,
>   Does anyone know where Xilinx hide their pin lists, in text format
>(not pdf) on their web site?
>
>I've given up trying to battle the various search engines.
>
>Ta,
>Allan.

Philip Freidin
Fliptronics

Article: 34134
Subject: FPGA Development Boards
From: Robert White <r.white@nallatech.com>
Date: Wed, 15 Aug 2001 09:53:01 +0100
Links: << >>  << T >>  << A >>
Hi Ali,

Nallatech do various PCI based FPGA development boards.
www.Nallatech.com

regards,
Robert

-----Original Message-----
From: aelmousa@yahoo.com (Ali) [mailto:aelmousa@yahoo.com]
Posted At: 14 August 2001 11:57
Posted To: fpga
Conversation: Development Boards for FPGA based Application
Subject: Development Boards for FPGA based Application


Hello All,

I am looking for reasonably priced development boards that use FPGAs.
The boards should be for application development and not for testing
purposes. They should use the PCI bus interface in a PC. I am not
interested in going into the details of programming the PCI interface
if an FPGA is used for that purpose.

It is preferable to have parts of the PCB board available for in-house
circuit additions also. Memory subsytem is not very important on the
board.

Any help with knowledge of availability of such boards, vendor
addresses, web pointers, prices etc will be greatly appreciated.

Thank you.

Ali


Article: 34135
Subject: Re: Building a clock out of a PLD
From: "Maki" <veselic@eunet.yu>
Date: Wed, 15 Aug 2001 11:02:56 +0200
Links: << >>  << T >>  << A >>
For that small frequency I would recommend 40106 ST hex inverter.
You only need resistor between in and out an cap between input and gnd.
Rest of the buffers You can tie in parallel so you can have more power on
the output.
This config works fine to approx. 1Mhz with 5V Vcc.
And less number of components comparing with 555 design.

Regards
M.

--
Veselic Mladen
Laboratorija Sigma
ECO Izenjering
Eric Inazaki <penfold@deadbeat.edu> wrote in message
news:140820012044292591%penfold@deadbeat.edu...
> In article <3B79C344.682A@designtools.co.nz>, Jim Granville
> <jim.granville@designtools.co.nz> wrote:
>
> > Eric Inazaki wrote:
> > >
> > > I have a PLD circuit which requires a clock signal.  I'm thinking it'd
> > > be really nice if I could use some of the otherwise unused gates
(along
> > > with a cap and a couple of  resistors) to generate the clock.
> > > Is this a bad idea, doomed to failure or is this sort of thing done
all the
> > > time?
> >
> > Somewhere in-between :-)
>
> I'm looking to do something in the few to few-tens of kHz.  Would you
> consider that to be at the low end of the scale?
>
> The circuit I have in mind has an inverter whose output is the clk
> signal.  This output also feeds a resistor (R1).  The other end of
> R1 is connected to a cap (C) and another resistor (R2).  The other
> end of R2 goes to the input of a buffer.  The buffer's output, the
> inverter's input and the other leg of C are all tied together.  (I
> know, pictures would be a big help.)  BTW, is this what you mean by
> 3 terminal design?
>
> >
> >  Low Frequency RC oscillators, of 2/3 terminal design, are impractical
> > in
> > CPLD due to lack of pin hysteresis.
>
> Ouch, that could be a problem.  I should go look through my data sheets.
> I don't suppose there are any PLDs that have Schmitt trigger inputs
> (either configurable, or hard wired)?
>
> >  For low Freq sources, we use HEF4541, available in SO14.
> >  For medium Freq, a TinyLogic single gate makes a good osc source.
> > You can quite safely build a 3 terminal OSC, (for higher precision),
> > using an external TinyLogic gate and a PLD 'gate'.
> >
> > These solutions also keep the Icc down.
> >
>
> For my purposes, if I can't do the PLD thing I'll probably just break
> out a 555.  I only need 2kHz or so and accuracy and stability are pretty
> much non-issues (or so I hope).
>
> >  At higher freqs, > appx 5MHz, it is possible to construct 2/3 terminal
> > osc, with care. You need to do your own margin testing.
> >
> >  Better may be to removce the R's and C's entirely:
> >
> >  We have designed completely buried oscillators in the ATMEL
> > ATF150X family of cpld, using a chain of foldbacks.
> >
>
> Any chance you could point me towards an app note, text reference
> or sample circuits?
>
> >
> > > With respect to timing circuits in general, can PLDs be used in
> > > place of discreet logic gates?
> >
> > If you mean RC timing, like 4528, 4093, 40106, HC14, then no.
> > If you mean counter chains, like 4060/4040 then yes.
> >
> >
>
> I'm thinking either a delayed monostable or a straight delay.
> The delay and pulse width would be on the order of few to tens
> of microseconds.
>
> > ======= 80x51 Tools & PLD IP Specialists  =========
> > = http://www.DesignTools.co.nz
>
> Thanks for all the input, you've given me quite a bit to chew on.
> I've actually just started doing things w/ PLDs.  PLDs rock, especially
> these isp types.
>
> eric



Article: 34136
Subject: Hysteresis behavior of an fpga buffer
From: "jfh" <jfhasson@club-internet.fr>
Date: Wed, 15 Aug 2001 11:08:07 +0200
Links: << >>  << T >>  << A >>
Hi,
I am working with an Actel FPGA, a A54SX32A, however the question interests
me whatever brand of FPGA.
I am wondering if there is a certain hysteresis behaviour on an FPGA buffer
? Is it an information I can find in the datasheet (I looked but did not
find) ? If I consider different IO standards (LVTTL, PCI are the two
available) can I expect a change concerning the hysteresis ?

Thank you,

J.F.



Article: 34137
Subject: Re: Xilinx pin lists in text format
From: allan_herriman.hates.spam@agilent.com (Allan Herriman)
Date: Wed, 15 Aug 2001 09:47:11 GMT
Links: << >>  << T >>  << A >>
Thanks Philip.

Silly me, I was looking in the databook section and the packaging
section of the web page.

Bye,
Allan.

On Wed, 15 Aug 2001 01:05:43 -0700, Philip Freidin
<philip@fliptronics.com> wrote:
>Here it is:
>
>      http://www.xilinx.com/products/virtex/vpackages.htm
>
>      http://www.xilinx.com/products/virtex/vepackages.htm
>
>      http://www.xilinx.com/products/virtex/v2packages.htm
>
>Philip
>
>
>On Wed, 15 Aug 2001 04:51:15 GMT, allan_herriman.hates.spam@agilent.com (Allan
>Herriman) wrote:
>>Hi,
>>   Does anyone know where Xilinx hide their pin lists, in text format
>>(not pdf) on their web site?
>>
>>I've given up trying to battle the various search engines.
>>
>>Ta,
>>Allan.
>
>Philip Freidin
>Fliptronics


Article: 34138
Subject: Re: Xilinx pin lists in text format
From: allan_herriman.hates.spam@agilent.com (Allan Herriman)
Date: Wed, 15 Aug 2001 10:02:59 GMT
Links: << >>  << T >>  << A >>
I just downloaded v2000efg1156.txt, and it seems to have an error.

The "package name" column has the following values:

------
VCCO_7
VCCO_0
D5    
B4    
F7    
GND   

This has the package names for the IO pins, but it has the supply name
for the supply pins.  I expected it to match the pin names, as in:
"U11" instead of "VCCO_7"

Anyone know why this is?

(I ended up cutting and pasting from the PDF anyway.)

Thanks,
Allan.



On Wed, 15 Aug 2001 09:47:11 GMT,
allan_herriman.hates.spam@agilent.com (Allan Herriman) wrote:

>Thanks Philip.
>
>Silly me, I was looking in the databook section and the packaging
>section of the web page.
>
>Bye,
>Allan.
>
>On Wed, 15 Aug 2001 01:05:43 -0700, Philip Freidin
><philip@fliptronics.com> wrote:
>>Here it is:
>>
>>      http://www.xilinx.com/products/virtex/vpackages.htm
>>
>>      http://www.xilinx.com/products/virtex/vepackages.htm
>>
>>      http://www.xilinx.com/products/virtex/v2packages.htm
>>
>>Philip
>>
>>
>>On Wed, 15 Aug 2001 04:51:15 GMT, allan_herriman.hates.spam@agilent.com (Allan
>>Herriman) wrote:
>>>Hi,
>>>   Does anyone know where Xilinx hide their pin lists, in text format
>>>(not pdf) on their web site?
>>>
>>>I've given up trying to battle the various search engines.
>>>
>>>Ta,
>>>Allan.
>>
>>Philip Freidin
>>Fliptronics
>


Article: 34139
Subject: Re: Building a clock out of a PLD
From: Jim Granville <jim.granville@designtools.co.nz>
Date: Wed, 15 Aug 2001 22:07:01 +1200
Links: << >>  << T >>  << A >>
Eric Inazaki wrote:
> 
> In article <3B79C344.682A@designtools.co.nz>, Jim Granville
> <jim.granville@designtools.co.nz> wrote:
> 
> I'm looking to do something in the few to few-tens of kHz.  Would you
> consider that to be at the low end of the scale?
> 
> The circuit I have in mind has an inverter whose output is the clk
> signal.  This output also feeds a resistor (R1).  The other end of
> R1 is connected to a cap (C) and another resistor (R2).  The other
> end of R2 goes to the input of a buffer.  The buffer's output, the
> inverter's input and the other leg of C are all tied together.  (I
> know, pictures would be a big help.)  BTW, is this what you mean by
> 3 terminal design?

Yes. When building this from non Hyst elements, the NonInverter (CAP)
stage should go first, then the inverter (Resistor) stage.
That way, regenerative feedback comes first, then the slower RC -ve
feedback
can come later.

> >  For low Freq sources, we use HEF4541, available in SO14.
> >  For medium Freq, a TinyLogic single gate makes a good osc source.
> > You can quite safely build a 3 terminal OSC, (for higher precision),
> > using an external TinyLogic gate and a PLD 'gate'.
> >
> > These solutions also keep the Icc down.
> >
> 
> For my purposes, if I can't do the PLD thing I'll probably just break
> out a 555.  I only need 2kHz or so and accuracy and stability are pretty
> much non-issues (or so I hope).

CMOS 555's are also a good solution - higher Icc than a 4541/40106, but
fewer pins..

> 
> >  At higher freqs, > appx 5MHz, it is possible to construct 2/3 terminal
> > osc, with care. You need to do your own margin testing.
> >
> >  Better may be to removce the R's and C's entirely:
> >
> >  We have designed completely buried oscillators in the ATMEL
> > ATF150X family of cpld, using a chain of foldbacks.
> >
> 
> Any chance you could point me towards an app note, text reference
> or sample circuits?

I've put an example on our web:

http://www.designtools.co.nz/lcd32ser.zip

 This is a LCD serial interface driver, and has a chain of 
foldbacks as a delay line, used for a Latch+XOR to drive a 
LCD backplane, using a ATF1502ASL.

> 
> >
> > > With respect to timing circuits in general, can PLDs be used in
> > > place of discreet logic gates?
> >
> > If you mean RC timing, like 4528, 4093, 40106, HC14, then no.
> > If you mean counter chains, like 4060/4040 then yes.
> >
> >
> 
> I'm thinking either a delayed monostable or a straight delay.
> The delay and pulse width would be on the order of few to tens
> of microseconds.

 For this scale, consider a monostable-counter, using the buried
Foldback
OSC, and a triggered saturating counter - you'll get zero external
components, and a time resolution of ~166nS



- jg

Article: 34140
Subject: FPGA for Reconfigurable Computing
From: jhmorris47@hotmail.com (Jason)
Date: 15 Aug 2001 04:19:03 -0700
Links: << >>  << T >>  << A >>
I'm just a newbie here and would like to know which FPGA would be best
suited for reconfigurable computing in terms of logic units, speed of
reconfigurability, etc. Any help would be appreciated.

Thanks
Jason H. Morris

Article: 34141
Subject: 2001 MAPLD Conference: Early Registration Closing, Last CFP
From: "Richard B. Katz" <rich.katz@nospamplease.gsfc.nasa.gov>
Date: Wed, 15 Aug 2001 07:34:43 -0400
Links: << >>  << T >>  << A >>


                        Program Announced

                   Early Registration Closing

                       Last Call for Papers

                2001 MAPLD International Conference
                     JHU/APL - Laurel, Maryland
                        September 11-13, 2001

Note new addresses: mapld2001@klabs.org
                    http://www.klabs.org

The 4th annual Military and Aerospace Applications of Programmable
Devices and Technologies International Conference will address devices,
technologies, usage, reliability, fault tolerance, radiation
susceptibility, and applications of programmable devices and adaptive
computing systems in military and aerospace systems. 

The program, abstracts, and registration information can be accessed at:

   http://klabs.org/richcontent/MAPLDCon01/MAPLDCon01.html

Early registration for the Conference closes August 24th, 2001.
Late registration will open on the 25th, either on-line or at 
the door.

This year's Conference will also include papers and an emphasis on
CPU design, logic design, and device reliability/fault tolerance.   

The program will consist of oral and poster technical presentations
and industrial exhibits.  This conference is open to US and foreign
participation and is unclassified.  Select papers will be published
in the AIAA Journal of Spacecraft and Rockets.

Late news papers will be accepted for the Poster Session, space
permitting.

MAPLD will present two tutorials/seminars:

   1. Programmable Logic Devices and Architectures
   2. Advanced Design: Designing for Reliability

Invited Talks:

   Major General Willie B. Nance, Jr., United States Army
   Keynote Address
   National Missile Defense Program Executive Officer;
   System Program Director for the Ballistic Missile Defense
Organization

   Dr. David A. Bearden, The Aerospace Corporation
   "When is A Satellite Mission Too Fast and Too Cheap?"

   Dr. Roger D. Launius, Chief Historian
   National Aeronautics and Space Administration

   Dr. James E. Tomayko, Carnegie Mellon University
   Invited History Talk
   "From Sequencers to Processors on Early U.S. Spacecraft"

   Dr. C. Dianne Martin, The George Washington University
   Invited Ethics Talk
   "Recipe for Disaster: Engineering without Ethics

   Dr. Don Bouldin, University of Tennessee
   "Platform System-on-Chip Design"

   Dr. Steve Guccione, Xilinx Corporation
   "FPGAs for Fault Tolerant Circuits"

   Eric Sundberg, National Reconnaissance Office
   Invited AIAA Talk

Technical Sessions:

   A. Applications: Military and Aerospace
      Session Chair: Ralph Kohler - Air Force Research Laboratory

   B. Design 1: Processors, Logic, and Programmable Devices
      Session Chair: Rich Katz - NASA Goddard Space Flight Center

   C. Reliability: Devices and The Effects of the Radiation
                   Environment
      Session Chairs: Dr. James W. Howard, Jr. - Jackson and Tull
                      Ken LaBel - NASA Goddard Space Flight Center

   D. Design 2: Systems
      Session Chair: Hans Tiggeler - University of Surrey

   E. Design 3: Fault Tolerance
      Session Chair: John McHenry - National Security Agency

   P. Poster Session
      Session Chair: David Hepner - US Army Research Laboratory

Panel Session:

   Design and Analysis vs. Test and Verification
   A Discussion of the Technical, Programmatic, and Ethical Issues
   in Military & Aerospace Systems

The conference is sponsored by: 

   NASA Goddard Space Flight Center
   JHU/Applied Physics Laboratory 
   National Security Agency
   Electronics Radiation Characterization Project 
   Digital Engineering Institute 
   Military & Aerospace Programmable Logic Users Group 
   American Institute of Aeronautics and Astronautics 
   IEEE Aerospace & Electronic Systems Society (AESS)
   Air Force Research Labs

For further information, please see the conference www home page at: 

   http://www.klabs.org/richcontent/MAPLDCon01/MAPLDCon01.html
   http://rk.gsfc.nasa.gov

Article: 34142
Subject: Re: Q: Revision and Database Control for FPGA Designs
From: hamish@cloud.net.au
Date: Wed, 15 Aug 2001 12:35:16 GMT
Links: << >>  << T >>  << A >>
Rick Collins <spamgoeshere4@yahoo.com> wrote:
> versions as being one of label control. The way Clearcase handles it,
> you can only access one version at a time, but with labels in PVCS, you
> can refer to one version for this component and a different version for
> a different component. Of course, you can't have both versions available
> at the same instant in time. But if your tool can compile the components
> separately and then combine the results, you should be able to support
> this unusual means of version control. 

Well then of course you can do the same with ClearCase.. you can
change your config spec, for a start. Or you can have multiple views;
that might be even better, because then you can see multiple versions
of the same file just by looking in different views (different drive
letters). Or you can refer to the file as \path\to\file@@\main\branch\version
etc.


Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>

Article: 34143
Subject: I need help disassembling a JEDEC .jed file from a PLHS18P8A
From: jonwil@tpgi.com.au (Jonathan Wilson)
Date: 15 Aug 2001 06:56:12 -0700
Links: << >>  << T >>  << A >>
I have a JEDEC file that identifies itself as a Signetics(Philips)
PLHS18P8A and I need to know how I would convert that file back into
logic equasions.
It says it was generated by BP-1200/84/SM48D if that means anything to
anyone...
If there is any way to get the logic equasions out of this file please
let me know.
I dont have access to the origonal PAL chip from which the .jed file
came.

Article: 34144
Subject: fpga dev
From: opende2001@aol.com (Opende2001)
Date: 15 Aug 2001 13:57:30 GMT
Links: << >>  << T >>  << A >>
Hello

I want to design my own sound chip using Fpga. The aim is to build a chip able
to play in hardware standard sound format as MP3, WAV... and emulate AY and SID
format. Is there some people interrested to help me in this project ?


Article: 34145
Subject: Re: I need help disassembling a JEDEC .jed file from a PLHS18P8A
From: Keith R. Williams <krw@btv.ibm.com>
Date: Wed, 15 Aug 2001 10:09:00 -0400
Links: << >>  << T >>  << A >>
In article <aa5d502.0108150556.2ceb06ba@posting.google.com>, 
jonwil@tpgi.com.au says...

> It says it was generated by BP-1200/84/SM48D if that means anything to
> anyone...

I can't help with the logic equations, but I don't think this number is 
going to help.  This number looks a lot like a BP Microsystems EPROM 
programmer.  

See (sorry for the split): 
http://www.bpmicro.com/web/Products.nsf/bf5c382ba7f803138625665a006e9bd
8/c7e74b488861a4ca86256a6c005b75f0!OpenDocument

----
  Keith

Article: 34146
Subject: Internal clock skew when using DLL
From: "Jamie Sanderson" <jamie@nortelnetworks.com>
Date: Wed, 15 Aug 2001 10:53:35 -0400
Links: << >>  << T >>  << A >>
Hi;

I have a question regarding the DLL and clock to clock skew with Xilinx
Virtex2 devices. I have two groups of logic which I want to run at different
speeds. One group is at 33 MHz, and the clock net is driven without using a
DLL (ibufg directly to bufg). This is defined in their PCI core.

The other logic would benefit from running at a higher speed, but I want to
avoid any metastability issues with crossing clock domains. My questions are
as follows: Should I feed the DLL using the bufg output, or should I tap
into the ibufg output? Secondly, will the software automatically account for
any skew between the clock nets? In other words, will it make sure that
setup/hold times are met when crossing from a register on the 33 MHz domain
and the 33*n MHz domain? Or, do I have to somehow figure out what skew is
and write an appropriate constraint? Finally, does it matter if I were using
the 2x DLL output, as opposed to the frequency synthesis output?

Thanks very much for reading!

Cheers,
Jamie



Article: 34147
Subject: Re: Building a clock out of a PLD
From: "luigi funes" <fuzzy8888@hotmail.com>
Date: Wed, 15 Aug 2001 16:07:57 GMT
Links: << >>  << T >>  << A >>

Eric Inazaki ha scritto nel messaggio
<140820011643075782%penfold@deadbeat.edu>...
>With respect to timing circuits in general, can PLDs be used in
>place of discreet logic gates?  In this particular case I'm using a
>Lattice ispLSI1016E.


In my esperience, yes.
I did oscillators just with Lattice 1K and 2K CPLD series.
You have to configure a macrocell as a simple inverter and
connect the input and the output to two adjacent pins.
Internally you connect the macrocell output to the clock lines.
Externally, you connect input and output with a resistor
and the input with a capacitor to ground.
This works in a very wide frequency range, also shorting input
and output directly and without any capacitor to obtain
easily 100-200 MHz!
Unfortunately this kind of oscillator is unreliable as it is unstable
and sensitive to noise, so you have to use it with caution.

Luigi




Article: 34148
(removed)


Article: 34149
Subject: Re: Internal clock skew when using DLL
From: Peter Alfke <peter.alfke@xilinx.com>
Date: Wed, 15 Aug 2001 10:18:19 -0700
Links: << >>  << T >>  << A >>
Since your two clock frequencies are fundamentally phase-coherent, albeit
perhaps with a certain unpredictable tolerance, you can cross the clock-domain
boundary simply by using the opposite edge of the higher frequency clock. This
does cut into your timing budget, but is safe otherwise.

Peter Alfke





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